When you pulled yours apart, did you measure the old tensioner for length when fully extended out of it's location? When looking at this, the research I've found and the handful of motors I've rebuilt over the years, there are only so many items that can cause this & the sounds I am experiencing. Mine only pulls this crap when it's warm and not when starting from cold.

Valve damage from a skipped tooth would be a whole different beast and constant from cold or warm start.

1. Oil Pressure
   1. Check valves
   2. Cam shaft adjuster magnets
   3. Cam shaft adjuster valves
2. Tensioner
3. Worn Chain Guides

I expect the tensioner to look fully extended when the cover is finally pulled and won't be surprised that when I test it, it isn't at the allowed 74.5mm measurement. I am wondering if I should pull the camshaft adjuster valves while I'm in there and inspect for debris, clean and reinstall as well...guess that wouldn't hurt and I'm already there.

When you had yours off and out, did you look at the timing chain rails and see if they were damaged from the chain slap?

 

What about the lower, auxiliary tensioner? Probably not the suspect since that would inherently effect both banks not just one.

 

Hi bro, to answer your questions, I did not measure the tension extension length since at the time i thought it's simple job and the replace of tensioner and check valve would be solve the problem for good. Now the rattling comes in about 7 seconds not since the very beginning and it lasts for quite a while, depends (sometimes couple of minutes, not phase out until i'm done warmup and drive out my drive way.

PS: in my case, I purchased both tensioner and check valve, however when I took the old tensioner off the check valve was already there, so I just left it as is.

From the youtube video (i guess that skilled guy is from Russia, he did series of videos about this rattling issues on 151/276/272/278 etc), I'm now in stage 2 meaning it rattles everyday. so what i need to do is to replace the adjuster once I confirm the magnet sensor is good.

 

If it’s the adjuster, seems that should be easy enough to diagnose once you have the cover off and advance the engine manually. It should be audible if the spring loaded pin jumps.

 

I agree with you. you remind me of something. during tensioner replacement last time, I manually turned the crankshaft and i did hear the jumping sound from bank 2 adjuster area and noticed the tensioner lever extending, at that point of time I thought that's the tensioner lever releasing pressure at TDC of #4 cylinder. I believe the bank 2 adjuster has to be replaced, I can open up and double confirm using the same method though.

 

That seems like a good diagnosis. Let me know how that goes. I am really hoping I don't find the same and that it's not just a chain rattle. Not that the extra $600 for the adjuster is not nominal, but I am hoping I really don't have to dig into the back side of the heads to lock everything down to remove mine.

It'll be another week or so before I get back into mine and I'll post here with what I find...it's a little bleak around here with detailed information regarding this and the solutions.

 

it seems a check valve and tensioner replacement can solve the rattling very well for many ppl. I hope this will be your case as well. Good luck bro.

 

UPDATE! I just finished the repair I outlined above...but to save scrolling time and to hopefully add some search terms here, I'll recap in addition to the insight that when I called my service advisor whom I really like and trust, but he's no mechanic, I accurately described what was going on and he let me know that it would be approx $10K to R&R Timing Chains for this repair:

Jumping into this thread as I am about to take this journey. 2013 E350 w just a tick over 80K on it. Car has always had the faint cold start rattle. Threw a code for Bank A/Cam 1 just after some longer start times noticed.

Symptoms progressed after the initial CEL:

1. Hard start, but started everytime (About 10X short <5 mile errands).
2. Last warm start emitted a louder than normal 'chain-slap' sound that cleared in seconds.
3. Driving home (less than 3 minutes) the car started misfiring but no other sounds to note.
4. Changed out the sensors noted with the CEL, cleared CEL car ran flawlessly for about 10min. Once at operating temps, the misfire and chain slap returned along with another CEL for the same code.

Fairly certain I have tensioner issue. Have ordered all new tensioners, chain ramps and check valves and cover bolts (I can return what I don't actually need).

I ordered the following parts from MBOEMparts which redirected the order to my local dealership which is less than 1 mile from my house...had I known this, I would have had them price match, walked over and picked up the parts versus waiting three days and paying an additional $23 in 2 day shipping, but I digress.

Tensioner 276050260064 1 $96.20
Control Valve Solenoid 2761560790 1 $39.22
Engine Camshaft Position Sensor 2769051000 1 $38.48
Hexalobular Bolt 000000006365 8 $32.56
Subtotal
$206.46
Shipping (FedEx 2 Day)
$23.31
Total
$245.77

Parts arrived today at 11a and once I pulled away from the office stuff, drop the wife off at her coaching gig I stopped by the local auto parts store and picked up an oil filter and Mobil 1 to do the oil change before I fired the car up.

All in, this repair took me about 3 hours, start to finish which included jacking up the car, removing the under belly pans to drain the oil, refilling the oil, re attaching the underbody and fire it up.

Do not let the manuals scare you...you can do this repair and you don't even have to fully remove the intake.

My culprit was most definitely a failed tensioner. Once I pulled the cover off of the passenger side and advanced the engine to 40 degrees past TDC, to ensure everything was in time, I could see that the tensioner didn't move a bit when it should during the cycle. Once I pulled the old tensioner out, if it were still in any working order, it should have extended. Mine didn't even budge. It remained fully collapsed. Once all put back together, the car fired up with ZERO rattle but unfortunately, I have a MAP Sensor issue now which causes hesitation and surging. I'll get that sorted in the AM. I may have damaged the original when I initially pulled the intake up. Good news is that it's a $35 part and about a 5 min job.

Initial tensioner:


Parts

Initial tensioner

Checking timing marks

Bad tensioner

New tension. Huge difference.

MAP Sensor

 

This is the same rattle that I have , I have 2013 E350 with only 52k miles and it would rattle even the engine is warm, I thought is the serpentine belt pulley , Thanks a lot for showing us the solution. did you replace the drivers side tensioner also?

 

can you please update after driving for a while to see it the rattle really goes away. In my case, I changed the tensioner on both banks, unfortunately rattle came back after short period of time. It must be the timing adjusters that has to be replaced.

 

Yes please. I had my tensioners and check valve done by the dealer yet the rattle is still there. Dealer said that this could be due to camshaft adjuster gone bad maybe because the tensioner and check valve were not fixed sooner?

Hope someone can post a DIY for replacing the adjusters as I don't want to spend 4K which the dealer is asking.

 

I wish I could give you guys a sweet sigh of relief with a completed repair but I ran into another issue, which is still related.

After the car settles into low idle, I get a codes for the intake cam being out of time. No rattles or other noises like before with the broken tensioner but I’m definitely off by at most, two teeth which makes sense since the chain was slack enough with the collapsed tensioner causing the issue. I am currently slowly working through removing everything on the passenger side to open up the valve cover to put the cams back in time which ‘should’ correct the issue. I’ll definitely write it up once I’m done with pics but right now I can’t get the dam fuel rail to separate from the fuel injectors. It’s really stuck and if any of you have tips...I’m all ears.

I am pretty confident that my issue was 100% oil related to begin with. Bad, low or dirty oil and the tensioner and advancer cannot pressurize the system.

 

I agree with your reasoning. Actually, my case started just after my oil change where I did not install the oil filter correctly which led to a failure of oil pressure hence leading to the rattle I believe.

 

We're making progress this morning. I was able to pull the fuel rail on the passenger side in which 2 of the three injectors came out attached (The two closest to the fire wall). These things are a bear. So far, the hardest parts of this has been getting at the lower bolt on the rear high pressure pump cover (you need a lot of patience and look past the forearm pain) and the fuel rail/injectors. Everything else is just unbolting things, labeling, etc. Side note: it's best you try to brush any dirt away from the injectors prior to doing this. I had a little bit of debris that fell into the open injector holes which I had to shop vac out. I am certain the cylinders wouldn't like the debris.

I have the special injector removal tool but the forward injector is really stuck so I am soaking it right now with some acetone in hopes it will pull loose a bit later this morning. Once that is out, I have a few additional parts including the high pressure fuel pump then I can pull the cover and see how far the intake cam is off. One thing I've learned over the years is to make sure you step back occasionally if you get stuck...or you're buying more parts.

Once this is all said and done, I'll do a proper write up as there is next to ZERO information on these repairs out there.

 

If your issue only the intake adjuster, you can get to it/change it out fairly straight forward, provided you have the special adjuster tool, without removing the valve cover. I'm not 100% sure the MLs have everything in the same spots as the E's but the process is pretty straight forward:

1. Remove air filter housing and intake (disconnect all requisite sensors & vacuum hoses)
2. Disconnect Cam sensors & Adjuster magnet sensors)
3. Remove Cam sensors (you'll want these out to check your work later)
4. Remove front cam cover
5. Set engine timing to 40 degrees after TDC
6. Remove Rear High Pressure Fuel Pump Insulation
7. Pop off the rear cover at cam
8. Remove chain tensioner
9. Mark timing chain & adjuster for reassembly. Attach special tool to intake adjuster while holding cam in place in rear and remove adjuster (You want to make sure NOTHING moves here).
10. Reinstall chain tensioner.
11. Check your work once the tensioner is back on by slowly advancing the engine to the 53 degree mark and make sure you see the adjuster marks in the middle of the cam sensor windows. If they are set correctly (which they should be, you didn't disrupt anything) your repair is complete.
12. Install and torque in reverse order.

Probably 4 hours start to finish for the first time.

 

Alright, we’re in! SO MANY LITTLE BOLTS at the back of the valve cover with the pumps, etc.

I made sure the crank was set to 40 degrees after TDC but I’m going to rotate it again 360 degrees to make sure I am not on a down stroke as the cams are both really out of time if where they are at currently is correct. The laser marks you see on the back side of the cams should be level with the head facing opposite directions.



Laser mark on the (L) Intake Camshaft shown should be 180degrees opposite and level with the head. The exhaust (r) should be head level facing right. We’re off quite a bit as she sits right now.

 

Question on the timing. Do you remove the Tensioner on pass side or drivers side first. When setting the
pass side the arrow on both cams should be facing down. At driver side when installing should be facing up on the arrows. Thanks

 

Everything I have read says:

1. Set Crank Timing to 40degrees after TDC
2. Remove everything to access cams
3. Install cam holding tools
4. Remove tensioners (passenger side first, then drivers side unless timing is only affected on passenger side)
5. Rotate cams so laser marks are opposite each other (the laser marks are the brown lines you see in the above picture). The intake (L in the picture) cam should be pointing towards the L (middle of the engine) and the exhaust (R in the picture) cam should be rotated so it points to the R.

I'm not sure where you are seeing arrows on the cams? If that's a thing, I need to recheck everything before I button it up and hit start.

 

I’m about to replace the passenger side intake can adjustmer. Can you please give me some insight? Does the chain have to come off? And part numbers or links to the camlock tool, and the adjuster tool? Thank you for your time and help

 

If you are removing the adjuster, you definitely need to remove the chain. Once you pull the tensioner, the chain will have enough slack to walk off of the teeth.

The $70 cam tool kit on Amazon and other places is all you need to lock the cams in place and comes with the tool to remove the adjuster.

Good luck, I did the whole R&R of that cam bank 4 times before I finally replaced the adjuster like you are. Spent a small fortune in gaskets and one use bolts but in the end it was far less money than the $10K the dealer quoted me.

 

but the lower chain doesn’t need to be removed right? Everything can be done through the front window right? Do I need valve cover gaskets? Or is it RTV?

 

This should be a recall at Mercedes. I sold my e350 and bought a e550. Same sound. Replacing under warranty. Mercedes came into my mechanic shop, heard the same noise on a c250. Crazy.

 

Front cover and valve cover are RTV, no gaskets. Just clean and apply.

Lower chain will stay put. You are going to be removing the following for this repair:

• Intake (and associated hoses, lines, etc)
• Cam Tensioner Cover
• Fuel Line/Injectors
• Spark Plug Coils
• High Pressure Fuel Pump
• Valve Cover

You'll need to replace all of the one use bolts on the cam tensioner cover, intake gaskets per MB articles.

I agree that this is an issue that MB should take care of but at this point, I already did the repairs (new tensioner, check valve, adjuster, position sensors). Start to finish, the passenger side was about a 6 hour repair. Hopefully I never have to do the driver side as more has to come off than on the passenger side.

I'll burn the car down before I do the driver side. For the record, mine has just over 80K miles on it...no way this should have been an issue. I have a Passat 2.5l that has over 250K on it and i do yearly oil changes which could be 15k or 40k depending on the year...

 

I have had both front covers off already, drivers side not that bad, maybe 2 more hours. But I feel ya, what a headache, and these cars are not that old. I’ll stick to BMW, lol. Thanks for your help

 

are the cams going to try to pop out when the valve covers come off?