OM642 Timing Chain Replacement DIY - GL 350 Blutech
 

Part 1 Disassembly of the Right Side Valve Cover

OK, so you start off by removing the right side air cleaner and the Y-shaped air duct that leads to the turbo. MB calls the “right side” of the engine the USA Passenger side of the engine so keep that in mind. In order to remove this, you start by removing the cross brace, and the access panel on the cowl. The cross brace is held by 4 large Torx screws, and the cowl access panel by a single 10mm bolt. I also pulled the rubber gasket from the cowl to get it out of the way.

The Y-shaped air duct is removed by loosening the three hose clamps with either a flat blade screwdriver or a 7mm socket wrench. Don’t try to pull the duct loose until you have loosened the air filter box on the right side first. You do this by unscrewing the two Torx screws that hold it in place. If you try to pull the air duct loose without doing this, you can damage it. The front screw is just below the oil fill cap and the other (a special bolt about 3” long) is a bit hidden, toward the fire wall. I pulled both bolts, then moved the assembly toward the right shock tower and lifted it out. There is a duct that connects to the filter housing that you should pull as well that leads to the grill. Set these aside. Now that you have the air cleaner assembly out, you can safely remove the Y-shaped duct and the associated gaskets. There are several electrical connectors on this duct, I mark them with blue painters tape and write a code on them to help me remember where they go during reassembly.


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Next you need to remove the return fuel line. This is a black fuel hose that attaches at each injector. The hose is in sections and connects with a circular connector on each injector. You carefully lift up on the plastic circular piece until you hear a clicking noise. I used a couple screwdrivers and it takes a bit of force. Disconnect all three, then life the hose assembly out of the way and set it aside.


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Next you disconnect the hard lines leading from the fuel rail to each injector. In the documentation, MB cites a special tool for this which is basically a crows-foot socket. I didn’t want to buy the special tool so I used flare nut wrenches, it was a 17mm. If you’ve done brake work, you have these in your tool box. If not, then it’s time to buy a set, they are very useful. Loosen each nut both at the injector and the rail, and lift out the hard line. You can only do small turns due to limited space, and turning the wrench over each time helps. I have a three tiered cart in the garage and had lined each shelf with cardboard, and set each injector line in the order that I removed them, marking the cardboard with a Sharpie so I would know where each went.


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On the back of the valve cover near the firewall is a bracket with several connectors on it. It’s held by two Torx screws. Those screws don’t go all the way through, so after you remove the bracket and bend it down out of the way, re-insert the screws so you don’t forget where they go.


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Now you can remove the fuel rail. First disconnect the hard line that comes over from the other side, then remove the two Torx screws that hold it to the valve cover. Again, reinsert the screws so you don’t lose them. Some fuel will come out when you do all this, just keep a rag handy to clean up any that spills.
Next you pull the injectors, which means introducing special tool #1 that I had to buy. In order to pull the injectors, MB calls for a slide hammer. The one I bought was actually for a VW/Audi application, but it was the most cost-effective that I could find. It has several adapters, one of which is M14 x 1.5 thread pitch, which is what the top of the injector has on it (where you disconnected the hard line.) You thread that fitting onto the top of the injector, then thread the slide hammer rod onto it. Then you slide the hammer weight up sharply and it pulls the injector out of its bore. Again, I placed these in order on my cart and marked the order in which I removed them. The factory manual calls for cleaning the bores by coating a round metal brush in a special grease, and scrubbing them, but mine where pretty clean given the low miles.


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Now we turn our attention to the front of the valve cover where there is what’s referred to as a vacuum pump. First you remove the black plastic box that is in front of it (I honestly don’t know what this is, but it appears to hold oil vapor or something as it’s hollow) by removing 3 Torx screws and lifting up and towards the front. There is an electrical connector that you then disconnect and move out of the way.

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Next you remove the four Torx screws from the vacuum pump itself and make sure that you grab the rubber coated gasket with it. This thing is filled with oil, so let it drain in a pan once you set it aside.

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Now you remove the crankcase ventilator from the back of the valve cover. It’s held on by two Torx screws, neither of which are within view. Use a mirror to find them, then put a finger on them to guide your wrench onto them. Once the bolts are off, wiggle it back and forth to remove it, it’s held in with an o-ring and pops out pretty easily.

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Now it’s time to remove the valve cover. MB specifies a specific order for removing the bolts. This is because the valve cover also serves to hold the camshafts in place rather than using cam trays. I’m sure this saves them some money, but if you screw up the cover during removal, you’re replacing the entire head (they are a matched set), so don’t screw it up. As a result, torque on these bolts are critical and the removal and installation order is designed to minimize stress on the camshafts, which are hollow and can’t take much stress. I don’t think the *exact* order is critical, just that you do it approximately correct. Basically you start in the center and work your way out. So you start with the center two bolts in the middle of the cover (loosen only, don’t remove them) then you loosen the outer two bolts in the center. Next you move forward to the next set of bolts and loosen them. Then you move to the set of bolts to the rear of the original center set and loosen them, alternating front and rear until all the bolts are loose. Continue in stages until you have all the bolts out. Again, set the bolts in the EXACT order that you removed them, on a piece of cardboard, so you know how they go back in. The center bolts have a sealant on the top to keep oil from seeping out.


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Now it’s time to actually remove the cover itself. First, verify that you have ALL the bolts out. There are (I believe) 30 of them, so it’s easy to miss one. Don’t mess with this; ruin this valve cover and you are in a world of hurt and will have to replace the head. Instead of using a gasket, MB uses Loctite 5970 sealing compound, which means that sucker is basically glued on there. You’ll use your slide hammer again to free it. Now, I didn’t have the adapter to use my hammer (which again, was for a VW/Audi application) so I had to make one. I used an aluminum ‘C’ that I had laying around, and drilled a hole through which I threaded one of the cover bolts. I used a hole near the front of the cover and inserted my adapter, then attached the tool using the same adapter for the injector (the photo is helpful here.) In lieu of this you can just buy the MB adapter, which I don’t think was that much money, I just neglected to buy it. Now, I’m going to tell you, that the first time you do this it’s nerve wracking. You are cognizant of the fact that if you mess up here, that you are truly screwed, so your brain doesn’t really want you to use too much force. But you really have to pull that weight HARD to get the cover to loosen. The first couple goes, nothing will happen, but eventually you’ll hear the tone of the “whack” that the tool makes when you hit the end of the slide hammer, change. That means you’ve broken the seal. Another hit or two and it will pull loose. Breathe a sigh of relief. At this point, the camshafts are exposed.


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Next you set the #1 cylinder (i.e. the one closest to the front of the engine) to Top Dead Center (TDC.) Top dead Center means that both valves are closed and the piston is at the top of the compression stroke. The easiest way to do this is to put a breaker bar with a 27mm socket on the crankshaft pulley nut and turn it until the camshaft lobes on the #1 cylinder are pointing up and towards one another. As you get close, start looking from behind towards the front and you will see that MB has cast some small holes in the cam gears. At exactly TDC the dots will be aligned perfectly and you can confirm TDC by looking at the timing mark on the crankshaft pulley which will be at 0 degrees. At this point, I highly suggest taking a grease pencil and filling in those holes so they are easy to spot, and also the 0 degree mark on the crank pulley.


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Now, leading up to this point you’ll want to start pulling the bolts that hold the sprocket that holds the chain, because you need to remove it. There are three bolts, but you can only access 1 or 2 of them at a time. There is also a pin that helps you locate the sprocket as well. If you forget to do this ahead of time, then you have to rotate the engine around a full cycle to get it back again.


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Once you have all three bolts off the sprocket, and the engine at TDC, then you can pull off the sprocket and pull it aside. I used zip-tires to hold the chain to the precise point on the sprocket so I didn’t mess up the timing, and also since you are going to separate the chain, you don’t want one end falling into the timing case, so I used a couple to hold both ends in place. Now it’s time to remove the tensioner from the cylinder head, and set it aside. Put a pan under there, as engine oil will drip out of the hole and make a mess of your floor. Then you remove the two bolts which hold the brackets which retain the intake camshaft, and pull the camshaft out. It doesn’t take much force.

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Now, I’m going to tell you that this is where I started to think too much. I decided to pull the left side valve cover as well because I couldn’t wrap my head around not knowing for certain that the other side of the V was in time with the right side. While this was excellent peace of mind, and helped me sleep, it was a complete disaster because removing the left side valve cover is 10x more difficult than the right side. My advice is: don’t do it. I’m going to guess that it added a solid 10 hours to an already long and tedious job.
Moving on; time to separate the chain. At this point, you have the camshaft out, you have the sprocket zip-tied to keep the chain from falling, and you have the chain zip-tied to the sprocket to keep it all in time. Now is time to pull out special tool #2, the timing chain separating and riveting tools:


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I bought mine off eBay, I think about $60 vs. a hell of a lot more for the official MB tool and other alternatives. There are two tools, and now we need the separating tool. The tool is a large U shape, and either end has a bolt in it; both are hollow. The larger hollow bolt has another smaller diameter bolt inside it, and holds a riveter. The tool came with several rivets for pushing the chain link out. At this point, you need to look at your new chain. The chain has two small dots indented into the top of each link. Check to see how your new chain, properly oriented, will mate with the chain in the vehicle. Note which pin you will have push out so that you can link the new chain to the old chain, or else you’ll have to rivet out another pin.

THIS IS IMPORTANT: stuff some rags into the spaces in the timing case so that you don’t drop anything down in there. If you do that, you’re screwed.
Place the tool onto the chain, make CERTAIN that you have the pin aligned properly and start cranking the nut on the tool to push the pin out. If you don’t have it aligned perfectly, the pin will hit the other side of the tool and prevent you from pushing it further. If you apply more pressure when this happens you could easily break the tool (remember, hollow bolts.) Eventually, the link will press out into the other hollow bolt on the back of the tool. Back the large bolt back out, and pull the tool away. You now have a separated chain.

Next step is to take the temporary link that comes with the special tool and link your new chain to the old chain. The temporary link has three parts. 1. A link with two pins that are grooved on one end; 2. A solid link, and; 3. A link that with cut outs to allow you to snap it into the grooves on the pins of #1.

What you do it place the new chain in position, insert #1 through the holes in the two chains, until the ends are visible. Then you insert link #2 over them (it’s basically a spacer), and finally you push link #3 onto the pins and lock it in place. Mine was very tight, so much so that I was worried about breaking link #3. So I took a micro file and filed the surfaces a tiny bit to make it easier to clip onto the grooves on the two pins. At this point, the two chains are temporarily riveted together into one long chain. In the photo, the temporary link is to the right of the brass colored link (no, I don’t know why there are different colored links.)

Reinstall the intake camshaft. You set it in place, then press down to compress the valve springs on (I think) cylinder #3. It take a little force, but not too bad. Now pull up the sprocket and set it back in place on the camshaft, ensuring that you align your dots. Take your time, this is critical that everything is aligned. Insert and tighten one bolt to secure the sprocket to the camshaft.


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At this point you need a helper; not just any helper, somebody who is as good as you are with cars. Take your time and wait until that person is available; you’re not doing this yourself.
The factory has another special tool (the damn Germans LOVE special tools) for this procedure. It bolts onto the cylinder head and prevents the chain from skipping a tooth while you are pulling it through. This tool costs something like $430, so no way was I buying it. I considered making one myself, but I thought about it a bit and came up with this:

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That’s a pry bar inserted between the chain and the cylinder head. It worked fine, but the guy holding it, and feeding the chain in and out needs three hands, but you’ll figure it out. This is not optional; you don’t want to mess this up and consequently mess up the timing.

This is how this goes; person A uses the breaker bar and the 27mm socket to turn the engine clockwise. Person B feeds in the new chain, and pulls pretty hard on the old chain to pull it out. All the while, person B has to make sure that the new chain is riding on the sprocket fully (to keep the camshafts moving and preserve the timing) and that the old chain is coming out. This pulls the new chain through and will eventually replace the old chain with the new one.

That sounds pretty simple right? But remember, the engine is at TDC, which means that cylinder #3 valves are compressed, and as soon as you start rolling that camshaft, the energy contained in those compressed valve springs is going to release. Fast. The first time this happens it will scare the crap out of you, so be prepared for it. Keep the pressure on your hold down device, and keep the pressure on the sprocket and pull that old chain out. After the first valve springs release, there will be some slack until the left side of the V catches up with the right, then person A will feel even pressure again while turning the crank nut. Person A continues rotating the nut and Person B continues feeding and pulling until the next time it jerks (this is roughly 4 partial turns because you only have so much space to turn the crank nut) until the new chain is fully in. Again, take some deep breaths. This whole process took about an hour (or maybe it just felt like it) because Person B has to continually find a place to put the old chain and reset the new chain which acts like a snake and generally doesn’t cooperate. I don’t have any photos of this process (because there was no way to) but you can find an official MB video on YouTube with a few searches, which is for a gas engine but it’s a very similar procedure.

At this point you have the new chain in place and the old chain is hanging down into the engine bay. Person A can now zip tie the new chain in place on the sprocket (both ends if you want to be safe) and then you can unclip the temporary link and lift the old chain out of the way. There should not be a gap between the links in the chain, instead you should be able to insert the double-pin portion of the special tool into the chain, closing the chain with no slack. If you’ve got slack, you’re going to have to really be careful and re-time the engine, but if you’ve done everything right yours should look like the photo below (the long link is the tool to assist in riveting the center link into the chain.)


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The next step is to rivet the chain back together. If you’re helper is still hanging around, you’re in good shape. Mine wasn’t so I left the sprocket on and fumbled through doing this with it in place. The difficulty in this is that, despite the WIS showing a photo of the chain being riveted with the sprocket in place, in reality the special tool hits the gear on the camshaft and puts it at an angle that won’t allow you to use it properly. So that means that you need to pull the camshaft again. My suggestion is to carefully mark the gears on the intake and exhaust cams so you are CERTAIN of being able to put them back into place while preserving the timing. This is absolutely critical. Now, again, place some shop towels into the timing case area so that you can’t drop any small parts down into the space. Once the camshaft is out, you can install the center link in place, push the temporary link through to hold it in place, then push the new link from your chain kit up against it. If you look back to the photos of the special riveting tool, you’ll notice four black blocks at the top of the case. This first step involves the block on the far right of the photo, as well as the block second from the left. You install them in the tool, and fit the tool over the new chain, so that the pushing block will push the new 2-pin link into the center link that you have held in place temporarily. This process forces the pins through that center link, and pushes the temporary link out. Continue to push the 2 pin link in until it is the same depth as the links next to it, then remove the tool and install the second set of blocks from the kit.


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So now you have the center link properly installed and you need to install the outer link. If you look closely at the pushing block that you have in your tool, there is an indent the exact shape of the end link, with a magnet that is flush to the block. You take the new link, and stick it to the magnet. Then you install the block into the tool and again, position the tool over the chain and press the new end link onto the two pins. Continue pushing until it is the same depth as the links adjacent to it.


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Now you have the new link in place, and the final step in the process is to crimp the ends of both pins to retain the link in place. If you look at the other links of the chain, you’ll see that the pins are dimpled in on the ends, 180 degrees apart. Now look at the pushing block that you just used, and you’ll see that if you rotate it 90 degrees, it will have a V-shaped indentation on it. Install it in the tool so that V-shaped indentation is facing the other side of the tool, and position the tool over the new link, centered on ONE of the pins. Crank down on the bolt and push the V-shaped indentation onto the pin. The spec says to crank it to 24 ft-lb but good luck getting a torque wrench on there while your holding all this with your three hands. OK, maybe if you have a helper. Back it off, then do the next pin. Inspect your dimples to ensure they look as good as the ones in the other links, and if not, press it in again. If they look good, pat yourself on the back, you’ve got a continuous chain in there again.


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Now you need to re-install the intake camshaft again and match up your timing marks. When I reinstalled mine, I coated the bearing surfaces with Red Line assembly lube, but if you don’t have that handy, then at least get some motor oil on there so you don’t have it dry fit. Once the camshaft is back in, install as many bolts as you can to reattach the sprocket to the camshaft, and torque the bolts to 160 Inch Pounds. Before you start rotating the engine to check timing, install your NEW tensioner into the side of the cylinder head. Torque it to 60 pound-feet. Now, using your breaker bar, rotate the engine around by hand and verify that your dots are linking up at TDC, and that the timing mark on the crank pulley is lined up at 0 degrees. Don’t just do this once, rotate the engine through several cycles and check the timing marks each time. When you are convinced it is right, you can start to button everything up again.

If you didn’t clean up the cylinder head and valve cover when you removed it, now is the time to do so. You need to get all that old sealant off of there and get a clean surface so that you can glue it down again. MB cites a special cleaner for doing this, but I just used carb cleaner and a rag. I stuffed rags down into all the crevices of the cylinder head so that none of the bits would fall down there. And when I was done cleaning I used a shop vac to try and clean them all up. You need to have an oil free surface to get a good seal and prevent any leaks.

Once you have the surfaces suitably clean, you need to get a tube of Loctite 5970 and put a 1.5mm bead all around. MB specifies a path to lay it down, and I found that the tube that I bought fit into a small caulk gun, which made it easier to dispense. You’re supposed to get the entire thing done within 10 minutes so that it doesn’t start to cure. You can see how to lay down the bead here:

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Place the valve cover on the cylinder head and screw in all your bolts finger tight. Then, starting in the middle and working your way out (just like when you removed them), you torque the bolts in 3 stages:

1. 35 inch pounds
2. 53 inch pounds
3. 80 inch pounds

There are something like 30 bolts, so this takes a while and it’s easy to miss a bolt, so take your time and check every one. Torque on these is critical because it’s what holds the camshafts in place.


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After you get the valve cover back on, reassembly is, as they say, the reverse of disassembly.

When reinstalling the injectors I again used the slide hammer to seat them properly. I installed new copper washers and o-rings on the fuel return line. The long bolts that hold the injectors in place are, I believe, one time use, but I re-used them and just put a small bead of blue Loctite about an inch from the bottom. These are torque to yield bolts, so you start by applying 62 inch-pounds, then turn it 90 degrees, then another 90 degrees.

The hard lines for the fuel system are torqued to 20 and 24 foot pounds, but since I didn’t have the crows foot socket, I just did it by feel using flare nut wrenches. You have to pay particular attention to how everything goes back together. Between the fuel lines, the fuel return line, and all the injector wiring, if you don’t get it all back in the right spot, you can find it difficult to get the air cleaner back in place, especially that foam rubber spacer. It helps if you take photos when you are taking it apart and reference them during reassembly.

Once you have it all together, check every connection again to ensure you have it buttoned up, and now it’s time to start it up. Because you’ve drained the fuel from the lines, it takes a few tries to get the engine to start. In my case, because I had taken off the left side as well and all those lines, it meant 5 tries, but it started up fine and settled into a normal idle.

How long did it take? Good question. I have two small kids and I travel a lot, so I was working an hour or two here and there, along with some marathon sessions when I could get the change. I’m going to guess it took me 30 hours, plus another 3 hours of a helper. If I had not removed the left side cylinder head cover too, I bet I would have saved 10 hours; that was a real bear, especially the EGR valve which is up under the cowl and in a terrible spot. I bet if I did this job again, I could get it down to 15 hours; there is one steep learning curve after another.

Awesome report

Awesome. And the Mercedes training videos make it look so easy!

Sticky please!

Kudos Sak335! appreciate the time and effort to take every pic and explain it

Thank you for the excellent write-up!

I hope to avoid future chain replacment on mine (137,500 miles on now) and am curious - how many miles on this 2012 GL 350 Bluetec?

Mine had 54,600 miles at the time it began rattling on startup. I immediately pulled it from the road (I have a third car...) to avoid damaging the sprockets too. The chain was well stretched (stupidly I didn't measure the new one so I can't tell how badly) but there was a ton of slack in the chain that wasn't present after the job was done, and the noise is no longer present at cold startup.

Wow what a job so glad that I paid to have mine done!! I had just finished the oil cooler repair which took way to long and decided I didn't have the energy or time to do the chain on top of it. I believe it was about a $2,000 job at the dealer.

It's pretty disturbing to hear worn out timing chain at under 100,000 miles - they should last the lifetime of the engine if they were made of proper materials, sized and lubricated properly.

Any speculation why these wore out prematurely?
Could it have anything to do with the recommended long engine oil chance interval?

Late reply but for my car I believe the oil either was not the correct type or got too low during its life before I bought it.

Great Job!
 

Whar brand is your chain (parts), or what bran do you recomend, since the original has the stretching problem?

I'm not sure what the OEM manufacturer is, but I used a Febi/Bilstein replacement. I'm not sure the actual chain is the problem; it's impossible to tell without any data.

Thank you for very through post!
How did you determine chain was stretch? Could you feel it on top of the gear if you pulled on chain at 12 o'clock ?

It's been discussed here fairly recently:

https://mbworld.org/forums/diesel-fo...tensioner.html

Yep, I've seen the tensioner looking "out of spec" posts...I am really struggling with these engines needing chains at <100k miles (or even 200k)
I have worked on diesel engines many years and stretch chains are rare(even marine at high HP duty cycle), anyway I would love to see confirmation of stretch directly on the actual chain, easy to see by pulling on it at the sprocket.
OM642 ruins chains at low miles=design issue for shure, and I bet MB will eventually be hit with a class action to pay for all the repairs(just like balance shaft issue on the M272 gasser)
"Keep your receipts".

My engine's failure at 82K miles was due to a combination of improper oil from the dealer along with faulty parts / engine design, as detailed in my thread here: https://mbworld.org/forums/diesel-fo...ne-seized.html

diesel315

Yeah I think stretched chains on those are rare because HD & marine Diesel engines usually have gear driven camshaft etc.
It would be pretty expensive to build V6 DOHC engine with gear driven camshafts which is why we have a loong chain to drive them!

I am getting my engine oil analyzed at each oil change and becoming more and more convinced that the factory recommended 10,000 mile oil change is part of the premature chain wear problem.
The iron level has been 54, 52, 115 & 59 ppm depending on how many miles on the oil (6,700 - 9,300 miles), VS. 47, 39, & 30 ppm with 2010 VW TDI with 9,000 - 10,000 oil change interval.

The TDI has no chain, it has belt driven camshafts. The belt is supposed to be changed regularly $$.

My 2008 BlueTec has just over 150,000 miles and so far the original timing chain is fine, but I am pretty convinced the extra iron is coming from normal timing chain related wear.

It will have future max 7000 mile oil change for sure (mine is almost all highway driving).

Cheers!

It's too bad, but as I recall you had incorrect oils mixed and went way way over the 10,000 mile oil change interval, combination of which caused oil turning to a sludge!

Not much in common with premature timing chain wear / replacement I think, but please correct if I am wrong.

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arto_wa:
Wow those iron numbers look high for a road vehicle, with relatively short interval(but I am no expert on the V6 Blutec, would need to compare others), they look like a heavy use marine diesel-type number.
I have older I6 CDI(no DPF), still uses chain(shorter run, easy 50%?) but the iron numbers are in <20ppm range, see below. I change under 9 to 10k miles.
Maybe it is a tradeoff with the oil, no-dpf can use "better" oil, ie Delo or M1 TDT 5W-40. I meant the V6/V8 Mercury marine diesels that seem to be doing OK, "so far" .(with timing chains, tensioners so-so)

I agree; based of what I have read I also think the higher iron content is related to the DPF compliant oil.

OP here. In my case, the vehicle was maintained to the letter of the maintenance schedule with the approved oil. The chain started making the telltale rattle at startup so I parked it and began the replacement process. I measured the new chain and the old chain and it was stretched 11mm at less than 55k miles. I've changed my oil change interval to 6k miles as I believe that the oil just can't take the 10k mile drain intervals but have no data to back that up. I'm 10k past the chain replacement without issues and will likely replace the tensioner every 25k as a preventative measure as well. I'm extremely disappointed in this vehicle, and M-B in general, but I see no realistic way to make them accountable aside from never buying another vehicle from them. This will be my first and last Benz.

sak335, I am truly sorry for your experience, and double thanks for posting a detailed procedure(probably while cursing MB!)
Sorry to say that 11mm strech does not sound bad at all on such a long chain, but obviously it fixed the slapping----I am still confused by these low-miles chain issues.
Last question, did you change or inspect any of the guides? They are thick and wear could affect symptoms.

It shure seems like some fresh-out engineer at MB decided to run the whole V valve train in one long chain instead of 2 or more, chain/guides must be in incredible stress, specially the "reverse" side of the V, I thought that was why other engines I have seen use 2 chains.

I agree with most of what you say but I don't think adding multiple chains would have made much difference if they were still undersized or under-lubricated.

Prime example is a Ford 4.0 V6 SOHC gasoline engine in year 2000 Explorer & Ranger, which used three timing chains! It was a disaster if owners followed manufacturers oil change interval like so many did (I have not and it's still fine after 230,000 miles!).

Incidentally, I bought a kit which included the timing chain, tensioner, and the guide rails. I decided against changing the guides because I couldn't find any wear on the ones that were visible, and the additional time required to change the ones that I couldn't see was just too great. Changing the chain instantly corrected the clattering noise on startup, so my assumption is that the stretched chain was the issue. It could be that worn guides contributed, but there is of course no way to know withouth replacing them and inspecting them.

Someone wanted speculation for timing chain wearing out early. If I knew for sure the country it was made in, (since it is a global market for auto parts manufacture now, and ALL auto makers farm out the work now instead of in house) I could then take a wild guess on the quality of materials and workmanship. There is a reason and either it is that the now modern younger engineers can't handle it, or the parts are manufactured in country's that have factory workers that don't give a rip about quality. Story after story in this forum and others, tells us that in the old days the engines and other automotive parts or units where way more reliable and durable, parts didn't wear out or break like they do now. So something has changed that is very obvious.

It actually is just the opposite - today's cars last lot longer than the ones made in the 60's for example, however they are way more complicated so comparison is not fair.

I think many people just complain naturally. It's the easiest thing to do.

Cheers!

I bought an OEM timing chain kit to replace the worn one. It was made in Germany by Febi/Bilstein. If you look around the engine bay you see parts from many countries in Europe, but they are primarily sourced from Germany. I'm convinced that the extended oil change intervals contribute to the failures, and I've switched to 6,000 mile drain intervals. I've only driven the vehicle 6,000 miles since I did the work, so I won't know for a long time if this is the correct strategy and there are too many variables to make a conclusion valid anyway.

I took my 642 engine apart after it bend the rod on water puddle and at 180k miles I don't see any excessive wear on the chain. Usually the wear shows first on small sprocket and even my sprocket might not look perfect, it looks decent.
From times I drove motorcycle I remember chain test by holding it sideways and observe sag. This one sags a bit, but I have nothing to compare it to, so can't say how much longer it would last.
Still long way from Fiat I drove decades ago and at 80k km (50k miles) the chain show outside after cutting the cover.
BTW there is long way from OEM part and original part.

https://cimg9.ibsrv.net/gimg/www.mbw...f7e19a320c.jpg
arto san: posted Jetta 2006 TDI oil test so you could compare with yours, Blackstone did comment on the lead, but not related to timing chain of course since it is rubber!
The only thing that caught our eye in this Jetta is the lead level - that shows above average bearing wear. Other metals were at decent levels (copper could be a little lower, but we're not complaining),
so we aren't ready to call this a problem just yet. Lead can also be driven up by a particle streak, which occurs when a piece of debris gets lodged in a bearing, displacing some lead. After it works free, lead drops with little to no apparent damage. No significant contamination was found, so let's just see how things look in another 7,000 miles.
I wonder if an extra-long tensioner would at least delay the Timing chain issue in the OM642, no idea if there is space.

I had read (if I recall correctly) that the low levels of zinc in todays' diesel-spec'd engine oil is to blame for increased wear. The newer oil needs to be low in zinc to protect the DPF, if I recall.

Torque spec waaaaay off
 

The correct torque spec for the bolts on the valve cover is 8Nm max. That's 6 lb/ft. I can imagine 80lb will ruin the bolt or the head

The spec is 80 INCH pounds as I correctly stated above.

I prefer not to post links because they expire eventually.

For the injector puller, do a Google search on "VW Audi Diesel Injector Puller" and you will find several versions. The key is that you need the 14 x 1.5 adapter.

For the Timing Chain Rivet tool do a Google search on "Mercedes Timing Chain Rivet Tool" and again, you'll find several versions. You need one that rivets a double row chain. I bought mine off eBay.

Glad things went well for you. If you look at my photos I had taken a yellow grease pencil and filled the holes with that so they were easier to see. It makes a big difference in visibility.

anyone knows a good shop or private mechanic in northern VA, DC or MD area that can replace the timing chain ? I can hear the ping when driving, also can hear the rattle when I start it in the morning.
2014 gl350 50k miles.

These guys did all my work before I moved from Northern VA:

http://benzeliteautomotive.com/

Any sprinter/freightliner shop can do it.

Buy have you called our local dealerships? They're pretty competitive sometimes.

Euromotorcars has a dedicated sprinter shop up in gaithersburg.

This is an excellent post and has been very helpful. I am currently replacing the chain on my car. I have the valve cover off and ready to put at TDC, but I can't see or find the location to see if the crank is at TDC. In one of the replies above it states you can see it by looking straight down from the top of the engine, but I have all sorts of pipes and things in the way. Does anyone know where it can be found or do I have to remove items off the front of the engine?

Also, I thought I would share what I used to pull the injectors and camshaft cover. I used a Harbor Freight slide hammer I had, item 60554. It has a hook that is perfect for sliding under the bolts on the cover. For the injectors, I welded a M14x1.5 nut onto a rod coupler that then screwed onto the slide hammer (M10x1.5 I recall). Not sure if HF still sells these new.

https://cimg8.ibsrv.net/gimg/www.mbw...145b120245.jpg

I changed my 2007 Sprinter OM642 engine with a 2017 OM642 engine.. camsensor error problem came out.. the seller of the newer engine told me i have to replace the old engine camshaft to the newer engine to make the timing right. Is this correct? How do i make the sure the get the timing right when i install the old engine camshaft to the newer engine? Thank you!

You should run a scanner before doing anything.

Swamping camshafts to adjust timing does not sound right

Regards

Joseph~

Between 2007 and 2017 lot of technology has changed even the OM642 engine have the same block.
The earlier had 1st generation DPF, when 2nd added DEF.
Whole new engine management and Sprinters have those engines detuned, so I can only wonder how camshaft become an issue.

someone from a MB Sprinter mechanic from Florida told me that the newer engine needs to be Teach In to my old ECU due to new injectors

Help.
 

So I followed this thread and got my chain replaced on my 2011, ML350 Bkuetec. Everything seemed to go just fine. But now when I start the engine has hard time starting and when it does it shakes quite violently when it runs.
any ideas what could be the problem?

How long after you had the chain replaced?

right away, it never started normally

Well then, something's screwed up on reassembly. Is there any possibility whatsoever that you're off by a tooth?

Upstream exhaust gas temperature sensor not connected? Sensor located on the bottom of turbo on the passagers side. Plug is on the rear corner of the valve cover. Check that as it may not give you a code for a while.

Does it crank normally soundwise?

When it runs rough, is it making hard injector nailing noises?

Messed up my timing
 

Hey guys. I tried to follow this instruction but failed miserably.. I am at a point where I pulled both valve covers, finished feeding the chain in, and aligning all the marks. One thing I totally didn't consider is the timing of the balance shaft. I thought hat it is just a pulley there so I was not worried about it while I was pulling the sprockets off and adjusting the new chain. I was going to see if I can remove the sprockets again and try to adjust the balance shaft to close enough position so that it is drivable, then get to the timing cover later and properly fix it. But now I think may have majorly screwed up. As I rotate crankshaft I feel pressure buildup approaching TDC. I wasn't honking when I was pulling the chain through initially, but now it occured to me that with all injectors and camshafts removed, there shouldn't be any pressure. Is that correct? Did I bend one of my valves while doing this? We did work through resistance while pulling the chain after a couple teeth skipped. Is there something else that could be causing resistance with everything removed? I noticed that crankshaft has another chain on it, to oil pump? Could that be causing resistance?

Do compression tests to see if there's damage ... if not re-time everything again - Sorry man doesnt sound good though...

My Benz Friends - I did oil cooler seals and I'm not gonna do another big job on the car again Its just a PITA and since I dont have a helper/ brother / cousin or neighbor that works on cars I'm usually the only one in the garage .... Quick question: Can I just remove some links from the chain and be done ? I know easier said than done but has anyone thought about that ? Is it worth a shot ?

thanks - 2010 GL350 - 75k miles - OCI 3500 miles since 44k

P.S: Any shops in Denver area ? I just moved here and dont know much about the city

I have not done the chain on OM642 specifically BUT I would not be shortening the chain under any circumstances.
in your case, I would be taking the front cover off and feeding the chain with proper timing marks in place.
Place an add in your local facebook market place or Craigslist that you're looking for help with this job if you feel its too much. I would certainly help if was near you!

Interesting tid bit, to take that front timing chain cover off, engine must be at TDC.
https://cimg5.ibsrv.net/gimg/www.mbw...e161bea73b.jpg
https://cimg6.ibsrv.net/gimg/www.mbw...1e01e040b0.jpg
https://cimg7.ibsrv.net/gimg/www.mbw...c1976c78d6.jpg

Thanks GoodbyeHonda - Not to mention this will require removing the front bumper, radiator, intercooler ... can you upload the whole pdf ?

Will upload that soon but here's the important part of timing the balance shaft.
https://cimg7.ibsrv.net/gimg/www.mbw...cc4f76eae7.jpg
https://cimg8.ibsrv.net/gimg/www.mbw...975b11dc53.jpg
https://cimg0.ibsrv.net/gimg/www.mbw...5801690820.jpg

The files requested

Thanks for your response. I have created a separate thread about crankshaft resistance and posted my findings and solution. I suppose I should update here too. Short of it is that gunk from the air intake fell into the cylinder and was preventing #5 piston from coming all the way up. This was because I failed to make sure valves were closed prior to cleaning. If you find yourself in a situation where you have intake manifold off and want to clean intake ports, check out my other thread. I have taken note of at which angle from TDC on flywheel each piston is at TDC, so that you can avoid my mistake without taking valve covers off.

1. OEM tool for holding chain cost around 100$. Holding chain with pry bar - extremely risky.
2. Can use any sealant from Autozone, instead of expensive Loctite.
3. No need to remove left engine cover at all.
4. Tensioner Must be replaced AFTER new chain is installed.

My video of this job on a Sprinter Van.
P.S. Finishing video doing same job on a single row chain Mercedes GL350

Thanks @sak335 for the writeup. I just finished this job, it didn't go perfect but I managed to recover. A couple of suggestions to add based on my experience
1) make sure you are at tdc of the compression stroke, double check timing marks as there are inner and outer marks on the cam gears. In other words the center marks can line up but the mark should be on a gear tooth on the exhaust cam gear and recessed on the intake gear.
2) no chain feeding tool is needed, you can use zip ties and while the process is a little slow it only takes one person and it's fairly fool proof. https://youtube.com/watch?v=s6rsgLBXofY
3) for insurance mark the exhaust cam, crank balancer and intake cam
4) I did not remove the tensioner before installing the new chain out of fear of the slack chain skipping. Installing the new tensioner was no picnic, I ended up pulling the passenger wheel and liner because the new tensioner kept cross threading. If you bend the metal wire holder out of the way you can use a 10 inch extension and make certain it threads straight. It should not be difficult to thread the tensioner, if you feel extra resistance stop and back it out, make sure it's threading true.

if I had to do this all over I would create a cam holder because when I pulled the intake cam (the second time to rivet the chain) the exhaust cam was under tension and it moved and could not be safely turned back to my marks. I ended up pulling the exhaust cam and rotating the engine back to tdc to re-time the cams. This surprise caused a bunch of stress and I ended up watching hours of video to feel comfortable I had the timing correct.

I marked my crank before replacing the chain and found the timing was way off, with the new chain everything is timed perfect.

FIY the just started emission recalls in USA for some model can extend timing chain warranty. Worth checking before spending money on it.

One other thing I forgot to mention. I purchased the same chain tool as the OP and while it got the job done I really hated the process of riveting the chain. The fact that you need to remove the cam to break and rivet the chain introduces significant risk. If I were to do this again I would explore the possibility of a chain breaker that doesn't require cam removal, I believe there are compact chain tools made for motorcycle chains that might work. A riveting tool that does not require cam removal could be made with relative ease from a small but heavy duty C clamp.

Got a letters from MB Bluetec Settlements Legal Administration and it does list timing chain for extended warranty.
The list has 23 points and it also covers cylinder head assembly components, camshaft, valves, springs, manifolds
So looks like beside lower engine parts (who are bulletproof on MB anyway) almost everything on top of the engine will have 4 years warranty.
This is informing letter, not actuall warranty, so I hope it will stay this way.
I have 4 affected Bluetecs in my stable and scheduled appointment on Monday to start the recalls.

@TxRzrBk

Thanks for the heads up on this. I’m getting ready to jump into this. I’m a novice mechanic, but will be assisted by a master mechanic. I’m just gonna go REAL slow. I like the zip tie method you use for feeding the timing chain.

Question regarding the cam holder, have you thought about how you would make this? I’ve seen some comments on ”cam balance” that have me a little freaked out.

Removing the sprocket
 

@sak335

“Now, leading up to this point you’ll want to start pulling the bolts that hold the sprocket that holds the chain, because you need to remove it. There are three bolts, but you can only access 1 or 2 of them at a time. There is also a pin that helps you locate the sprocket as well. If you forget to do this ahead of time, then you have to rotate the engine around a full cycle to get it back again.”

Question: Do you start removing the sprocket bolts prior to setting the engine at TDC since it seems you have to rotate the engine to get to all the bolts that hold the sprocket in place?

Thank you.

NapaGL320; yes, I don't see any reason why not, but you have to ensure that you don't pull them too soon, because otherwise you'll get the engine out of time if you pull all three but still need to rotate the engine.

Camshaft cover removal
 

Followed @sak335’s instructions on the camshaft cover removal and it went swimmingly. Connected the slide hammer at the same spot, 10-12 solid strikes and it separated so well I finished separating in by hand. Used a 2lb slide hammer from harbor freight, about $27.00. It came with an attachment that worked perfectly so I didn’t have to make a special attachment.
https://cimg9.ibsrv.net/gimg/www.mbw...f024ee95a.jpeg
https://cimg3.ibsrv.net/gimg/www.mbw...cd10676f6.jpeg

Timing off?
 

@sak335 @TxRzrBk Just removed camshaft cover. Have not broken chains. Rotated engine clockwise to view timing marks as you recommended. Looks my timing is one tooth off being that I’m 20 degrees ATDC (after top dead center) to have my camshaft timing marks align. First set of pics is camshaft marks at TDC on crank. Camshaft obviously not yet aligned. Second set of pics is camshaft marks aligned and crank at 20 degrees ATDC. Planning on advancing camshaft one tooth forward.
https://cimg2.ibsrv.net/gimg/www.mbw...12ee28653.jpeg
https://cimg4.ibsrv.net/gimg/www.mbw...586e82b30.jpeg
https://cimg6.ibsrv.net/gimg/www.mbw...4a99e1192.jpeg
https://cimg0.ibsrv.net/gimg/www.mbw...5d3693895.jpeg

Timing cover, left camshaft cover
 

Well, since my timing was off on the right side I’m not convinced that the timing on the left is correct either. So I’m going to take off the timing cover and left camshaft cover and time the whole damn thing. And since I’m in there I’ll probably replace the timing chain guides as well. Here we go...

I'm in the process of pulling my engine apart to correct the issue of high oil consumption.
It's interesting that my timing marks were off like yours are. I'm wondering if my chain could be stretched by that much?

Had your timing chain ever been replaced? It could be a skipped tooth (not saying you did it). That’s what we’re trying to determine with my GL. Stay tuned...

I don't know what the previous owner did (former Police vehicle). It surprised me enough to question if the timing was set that way on purpose or had the chain stretched that much. I've ordered a new chain and will compare it with the old one to see if there's any difference in length.

Timed
 

It may be a combination of your tensioner and chain stretch. Here’s the after picture of the timing with a new chain and tensioner.
https://cimg5.ibsrv.net/gimg/www.mbw...cbfedbc61.jpeg
https://cimg0.ibsrv.net/gimg/www.mbw...8637820ce.jpeg

Balance shaft
 

@sak335 Ok. My timing chain is in. Cams and crankshaft are aligned and time perfectly. My concern is the balance shaft. Has anyone experienced the balance shaft being out of time after changing the timing chain? If so, what should I expect to feel in the car? Thank you in advance.

UPDATE
 

My timing was not off. I just needed a new chain and tensioner. Ha ha. Once installed the timing was dead on (see pics in previous post). Also, I started to worry about the chain skipping on the balance shaft when the valve springs released as you draw in the timing chain. The valve springs release three or four times during the process. Just keep tension on the chain. @TxRzrBk has a great method of drawing in the chain that keeps tension on it the entire time and can be done by one person. I DIDN’T do it this way which cost me some sleep thinking the chain had skipped on the balance shaft. So, I took the sprocket off the camshaft and timing chain (I used zip ties to mark where the chain linked together) and just looked inside to see if there was anything noticeable that would put me at ease. And there was. There seems to be a little lip or ledge on the inside of the timing shaft cover that keep the chain from falling off the balance shaft teeth. You can see this is the picture. Anyway, I’m way more certain that the balance shaft timing is fine as is the left camshaft.
https://cimg4.ibsrv.net/gimg/www.mbw...fcdcc9cd7.jpeg

Timing chain on
 

Timing chain on and timed perfectly.

Now I’m going to cleaned the surface of the camshaft cover and the cylinder head and prepare it for the RTV gasket. I’m using Permatex’s RTV silicone dissolver (NOT their gasket remover, although I AM using that to remove the vacuum pump gasket). Permatex’s gasket remover is not intended for use of RTV. I guess I could use it but I’m not willing to risk any mistakes at this point so I’m using Permatex’s silicone dissolver. Also, do NOT scrape the RTV gasket off with a razor or scraper. You’ll mar the aluminum and possibly damage the head or cover. I like the silicone dissolver because it makes the RTV a little sticky and will wipe off with a rag or shop towel vs having little hard pieces that might fall into any gaps. You can see I’ve packed the head with shop towels. After I clean the head surface I’m going to carefully vacuum everything.
https://cimg3.ibsrv.net/gimg/www.mbw...47b5122e4.jpeg
https://cimg9.ibsrv.net/gimg/www.mbw...e66d7bc00.jpeg

Loctite 5970
 

I couldn’t find Loctite 5970 locally. I found it on eBay and FCP Euro’s site, but I didn’t want to wait for it to be shipped (plan ahead).

The MB part number is 003-989-982-010. I called my local MB dealer’s parts department. They had plenty of it for about $25 USD.

NOTE: I tried to find a Permatex alternative but I could find an exact match. I suppose you could use their high temp RTV silicone sealant, but it’s not an exact match and I felt more comfortable using the MB OEM solution.

I used loctite 5699 ordered from Amazon, this worked fine and I'm confident many rtv products would work fine, the prep is the key.

When I aligned the timing marks before replacing the chain I was at almost 30° atdc, with the new chain in it was dead balls on zero. I didn't bother to pull the driver's side valve cover.

Completed
 

Ok. All done. My 320 is perfectly timed, dead nuts and purrs like a euro diesel should. Thanks to @sak335 and @TxRzrBk for the adds to the post. Very helpful. If I were to do this again (and I would even knowing what I know now) I would draw the new chain in exactly as @TxRzrBk shows in his YouTube video. The chain breaker I used didn’t have the correct size part for putting on the final master link correctly so I had to improvise. I’d buy the right tool for that part. Confirm and double confirm. Lots of learning. Take lots of pictures, at every step. It’ll save you the headache of wondering how things were positioned. Mostly take your time and make sure you clean your parts and PREP PREP PREP the head and camshaft cover before putting them back together.

https://cimg6.ibsrv.net/gimg/www.mbw...66de3855c.jpeg
Wrong tool. The master link faceplate doesn’t fit even though the information in the ad listed it as compatible with the 642.

https://cimg5.ibsrv.net/gimg/www.mbw...618885493.jpeg
Head prepped for cleaning. You DO NOT want to get anything into the head or timing chain cover. That’ll be a wrap if you do.

https://cimg1.ibsrv.net/gimg/www.mbw...60a54c5f2.jpeg
Get the right chain link tool. Spend the money. You don’t want to do this.

The video is what it sounds like now. The air filter isn’t on yet because I was bleeding the fuel rail and checking for leaks. It’s even more quiet with the air filter back on.

Thanks for all the awesome descriptions.

I have a couple of stupid questions:
1. Which way does the engine rotate (from front of car looking at front of engine). I'm assuming clockwise for some reason.
2. Is the camshaft hold down tool needed? Would a piece of wood bolted down work? I can't seem to find a camshaft holder at a reasonable cost.

Thanks.

1. Rotates clockwise
2. No. You don’t need a camshaft hold down tool. I thought I might too but you don’t.

Read my post regarding the cam shaft hold down. If I had to do it again I would make a cam shaft hold down with a piece of wood.
Measure the distance between the cams, Take a 1x4 or 2x4 and drill a pair of approx 3/4" holes spaced to match the cams, cut the wood splitting horizontally across the holes, drill to line up with valve cover bolts.
I'm not sure why I am the only one who seems to have had this problem but it added a significant amount of uncertainty to the process.
​​​​​​​

@TxRzrBk thanks. I had read your post with interest. As far as I could tell you are the only one who had an issue and I don't think I've seen anyone else use the hold downs. I think I'll know some up out of wood as you suggested. It should be pretty easy to do and then guarantee that I don't need it.

Job done.

Pretty hard to get wrong if you take your time. I did this with out a helper.

A few things I'd do differently or wish I'd thought about:
1. It's a 4 stroke engine, so the for each crankshaft rotation the cams only rotate half a turn. Not crucial, but would be one less thing to thing about on the fly.
2. You are likely going to have to take both cams out. Just accept it early, do it and then clean the rtv off with them out. So much easier than getting everything done and then cleaning.
3. There is a lot of tension from the valve springs at TDC. I couldn't reset the cams so had to rotate 1/4 of a turn. Initially I was worried about messing up the timing, but see below.
4. It is really hard to screw this up. The timing chain socket has a locator on the cam shaft, the cam shafts are marked so you can pretty easily realign the two dots. Just mesh it up and rotate as you drop them in.
5. Keep the tensioner in. It makes you feel better that the four hidden cogs won't slip.

Things went well until I pulled the chain through and had a one cog gap. The chain had slipped, although no idea where. I guessed which side had slipped, joined the chain and continued up. My timing marks didn't line up and I slept on it. I decided no wishful thinking was going to make it right, so took both cams back out, dropped the socket down and rotated the chain on one cog. Marks now align perfectly. Struggled to reseat the cams, so had to rotate crank to reduce spring tension. Note that this is without socket on cam, so need to make sure you mesh the dots on the cam and then drop it in as you rotate to get sprocket cog lined up with the cam.

It took a lot of effort to shift the chain one cog. Both times. With cable ties it's a relatively simple one person job.

I didn't measure the new chain, but 9.525mm pitch and 190 links, meant my old chain was about 7mm longer. I'll upload pictures of the tensioner, but significantly reduced how much it was sticking out.

Sigh....facepalm~roughly 20k miles since I replaced the chain and the problem is back again. It's making a brutal metallic knocking, clicking noise at startup exactly like before. But wait, there's more...this time around there is a persistent ticking noise at idle, the noise can be heard faintly even at higher rpms. It honestly sounds like a spun rod bearing but I am hopeful that's not the case.
last night I pulled the chain tensioner hopeful that was the problem. The tensioner wasn't over extended like the OE tensioner and there was not anything obviously wrong with it. I'm not aware of any official test I could do on the tensioner so if anyone has suggestions please chime in.
I have a few theories: 1) the tensioner simply doesn't have enough travel to account for this engines propensity to stretch chains 2) the true problem is actual low oil pressure and the engine is basically scrap 3) the chain itself is compromised, perhaps the link is partially loose.
Fyi I used a febi-bilstein timing chain kit

Perhaps you could borrow the OM642 timing chain stretch tool to see if chain is the problem? Its not cheap. Attaching file for instructions.
and with that ticking sound, perhaps injector seal is gone so check all injectors?

I'm 99.9% sure the noise at startup is the timing chain. I just can't rationalize the chain being stretched after only 20k miles but it's clearly possible.

This would be a good time to drain the oil and send sample for analysis. I would also inspect oil filter for any particles. Perhaps one of the guides failed.
inspect your plastic oil filter holder stem closwly as apparently they can fail over time and cause lubrication issues.

@TxRzrBk Could it be that the guides are worn? I read on a sprinter forum someone saying that the guides should be replaced at the same time. The level of effort in replacing the guides vs just chain makes the chain replacement worth the risk.
However the tensioner then should show a large extension.
Can you post up a photo of the tension position. I'll try and grab a photo of mine.
The tension measuring tool would be nice, but it's pretty much as expensive as a chain. May as well replace the chain and measure the old one. At least you can recheck the timing and ensure that isn't the issue.
Would be good to record the sound also. Just incase it is the worst outcome. I have NFI what a spun bearing sounds like.
Mine is currently making some noises, that I'm hoping are belt related. The tensioner bearing seemed a bit noisy, so hoping to give them all a check when I have time. I'm also due an oil change, so filter inspection will happen - it may be worth pulling your oil filter. You don't have to dump the oil to get to them, so worth buying a new one to carefully check for metallics. Spun bearing should be dropping deposits in the oil.

lol, I should of read this before posting. Same but less words.

What's the oil change interval? I hope you're using CK-4 oil.

Oil is changed at 6-8k intervals using MB approved oil.
I did not take a picture of the tensioner but it is definitely not over extended like the OE tensioner was before I replaced the chain.
The only thing I can imagine wrong with the tensioner itself would be a weak spring or simply not holding oil pressure.
I have very little faith this will make a difference but ...I'm going to try replacing the tensioner with an OE tensioner and see if that helps. I will update once I get the part and get it installed.
regarding the guides, I have a new set of guides that came with the febi timing chain kit. I'm not familiar with the replacement procedure but I would imagine it's quite difficult and might even require pulling the engine.

MB approved oil is for gasoline engines, not diesels hence the timing chain stretch.
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Getting the chain guides installed is a project. You have to pull the front timing cover which requires pulling the oil pan which requires pulling the engine from the car. If your car has a removable subframe you might be able to do it in the car. It's a massive project regardless. You could go in through the oil cap with a boroscope to inspect the guides. My guides still looked new at 220k miles but I replaced them anyway because I was doing a complete rebuild.

By MB oil, I mean oil approved for this specific vehicle...this ain't my first rodeo

I'm not sure if you have to drop the pan to get the timing chain cover off. You do have to remove both cam covers though. So It's a big job (twice as big at least).

This row of screws attaches the upper oil pan to the front timing cover. You can only access these screws by dropping the lower oil pan and pickup tube. When reinstalling the front timing cover it needs to go back on the engine BEFORE the upper oil pan. So one way or another upper oil pan is coming off if you want to do the chain guides.
https://cimg8.ibsrv.net/gimg/www.mbw...0a0856e902.jpg

Also the upper oil pan cant come off without the rear crank seal coming off first. The rear crank seal bolts onto the block and upper roil pan. That means engine needs to be separated from the trans. The bottom 3 bolts around the seal attach to the timing cover.
https://cimg0.ibsrv.net/gimg/www.mbw...6e1f760644.jpg


I suggest just inspecting the chain guides with a boroscope camera and replace the chain through the passenger side valve cover. Oddly enough in this engine the plastic chain guides tend outlive the chain.

Yes I know, 229.51 and 229.52 oil that lacks an API CK-4 diesel oil rating because it's engineered for gasoline engines not diesels. These oils don't contain soot dispersant chemicals common to diesel oils so the soot ends up working as an abrasive in the timing chain elongating the holes where each link pivots. This is the reason your timing chain stretched despite your short oil change intervals. The metal in each link didn't stretch, the holes in the links expanded. Keep using 229.51 or 229.52 oil and you'll be replacing the chain yet again.

Good luck

OK, now I'm completely confused. The point of the dispersants is to keep the soot in suspension in the oil. Doesn't it then stand to reason the soot would be more efficiently carried to the chain (and everywhere else) where it could more easily do its dirty work?

So, what are the tradeoffs between using the CK-4/MB228.51 oils, the MB229.51 oils and the MB229.52 oils? (Besides the 3% decrease in fuel consumption.)

Dispersants in diesel oil prevent the soot from clumping together and turning into sludge. It also binds to the surface of the soot so it can't stick to metal surfaces in the engine where it can do damage.

All I can tell from the data Mercedes provided is that 229.51 oil is recommended for a bunch of gasoline engines and 228.51 oil isn't. I've never seen an 229.51 or 229.52 oil bottle that also carries an API CK-4 diesel rating. If someone finds one please correct me. I have seen SN gasoline rating and 229.51 on M1 5w30 ESP. Every 228.51 oil I've seen also has the CK-4 or the older CJ-4 diesel rating somewhere on the bottle.
https://cimg4.ibsrv.net/gimg/www.mbw...e46c57d8a7.png

I think most of the fuel economy claim comes from the use of low viscosity oil, not the additives. There are similarly low viscosity CK-4 oils with the appropriate diesel additives if that's what you're after. The whole goal of recommending these low SAPS gasoline oils for use in diesel engines was to protect the DPF from clogging up with ash before the emissions system warranty runs out. If that comes at the expense of your timing chain, well that's your problem not Mercedes'.

tjts do you have any lab tests to support all those theories?

I asked mercedes to release any lab tests they used to come up with the 223.2 sheet but they didn't respond. You should ask them too, maybe you'll have better luck. I'm glad to see you're as skeptical of their theories as I am.

What makes me different from you is that I put money where my mouth it and pay for lab tests.
Never had any oil-related engine problem on about 20 MB i bought for me and my family members and I follow FSS or Assist recommendations to full extend, even exceeding them occasionally.
Bare in mind, FSS originally was programmed for using dino oils and my 1998 ML320 was running 13k intervals on dino oils just fine, before lawyers forced MB to change the recommendations.

Actually, a least for my OM651, I'm pretty sure the timing chain is covered by the extended warranty.
(Confirmed:
The emission control system warranty shall cover the following parts or systems:
...
• Engine timing chain,
...)

That's great news for your 651. Perhaps TxRzrBk can get his timing chain replaced under warranty. I'm guessing MB will find an excuse to deny the warranty claim but it's worth a try.
That 229.51/229.52 gasoline oil really f***ed him over.

I'm sure that's the only possible cause for his problems. :rolleyes:

Not like any rod bearing I've ever seen... (or heard).

If you've got a different idea I'm sure TxRzrBk is all ears. Or are you suggesting he keep doing the same thing and expect different results? Timing chain replacement every 20k miles on 229.51 gasoline oil sounds delightful.

Respect to your knowledge. The photos of the oil sump are awesome illustration of being correct in what you say.

Something would have to be stuffed in the engine to wear a chain in 20k miles. My original chain had 200k kms and doubt it had anything apart form the standard oil. Assuming the oil isn't contaminated and watered down with diesel or gelling with biodiesel, the chain should still be ok. If the tensioner is not extending, then either the chain is not stretched, or the tensioner is broken. It doesn't seem plausible both the tensioner and the chain would both fail after such a short time. I had a look at my tensioner, it is only extended about 5-10mm, about 1/3 what it used to be before the chain replacement.

Go through all the injectors. Make sure there are no fuel leaks on the high pressure side, nor any leaks through the brass washer on gas side. Injectors tend to tick louder when they have issues.

Check your accessory belt and pulleys. Don't think ticking would come from that but it's something that you would have touched to do the chain.

Then I guess you could start to put a screw driver on different parts to see whether it gets louder somewhere. HP fuel pump, AC compressor, heatsheilds?

1) there doesn't seem to be a rash of timing chains failing at 20K miles.2) just because he used 229.51 oil and had a timing chain failure doesn't prove cause and effect. Maybe it's the brand of cigarettes he smokes.
3) I have 80+k miles on the original chain. Carfax indicates regular dealer servicing for the first 70k. Does that prove anything?
4) if the chain is wearing abnormally, wouldn't that show up as metal in the oil analysis?
5) we don't actually know for sure his current problem is the chain, or if it is somehow related to something that happened during the previous replacement.

It would be really helpfull if you could explain the reasoning behind the recommendation of 229.31, 229.51 and 229.52 over 228.51. That way we could make our own decisions rather than relying on non-scientific statements like "That 229.51/229.52 gasoline oil really f***ed him over.".

If you're going to use 229.51 gasoline oil in your om642 diesel engine, stock up on zip ties. You're going to need them.

Are you old enough to know what "you sound like a broken record" means?

Some idioms still last for generations and are repeated when nobody remembers where they come from.
My favorite is

'Don't throw the baby out with the bathwater'

care to find explanation without google? :confused:

Fixed!
 

I got the new tensioner today and installed it. Mind you I already removed and checked the existing tensioner and did not find anything wrong with it. When I removed the tensioner previously I pumped all of the oil out of it so that I would have less hassle getting it to thread straight.
Today when I removed the tensioner for the second time there was a very small chunk of what looked like casting sand lodged in the oil inlet. I tried to remove the debris with a small pick and it fell back into the tensioner so I'm still unsure what it is.
I checked the two oil ports on the motor side and found them to be clear.
After installing the new tensioner the chain slap at startup is gone and the motor sounds normal.
I think I dodged a bullet on this one however time will tell if there is any lasting damage.

Touché. I'm glad someone else had a problem getting it back in. I put in a new tensioner (old one looked fine, but I'd already bought a new one) and was shocked now much force was needed to compress the tensioner before the threads engaged. At one stage I even thought i'd cross threaded it. I'd forgotten that little nightmare.

Glad it was a simple fix. Well done picking up the noise and doing something about it.

Edit- the INA chain does not have oil holes...it also came with moly "break-in" lubricant
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There is a top and a bottom of the timing chain, the oil holes between the teeth need to be facing up. I did not think it would be possible to install the chain upside down until I saw a video of a guy installing the chain that way...I am still not sure how he did it.

As an aside, I am about to replace my chain for the second time due to a clogged tensioner that stretched the chain yet again.

I ordered an INA timing chain and it came riveted together, when I replaced my chain before I used a febi chain and it did not come riveted.
Did anyone else have to deal with this?

Yeah, what's the problem?

Do you reuse the pins? It didn't come with new pins.

I thought you said it was already riveted together. Or, do you intend to break it and feed it in then reconnect it?

Yes sir, I'm using the method which is the topic of this thread, the new chain is temporarily attached to the old chain and fed through the engine and finally riveted together.
To my understanding any other installation method is 10 times more effort

Most likely, but you get a good look at all the guides, sprockets, and the tensioner.

Makes me glad I'm no longer trying to make a living wrenching on them.

Just completed second chain replacement. I made one improvement to the process. Instead of removing the cam cover with a slide hammer I used a 1" PVC coupling tapped with a dead blow hammer into the opening for the vacuum pump. I did need to sand a slight chamfer into the leading edge to get it started straight. This was far faster and IMO less risky than the slide hammer route.
https://cimg6.ibsrv.net/gimg/www.mbw...907e4b7c85.jpg
Improvised cam cover removal tool