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It wont release the chain but will remove tension that you can slip it on and off exhaust cam sprocket.
Perfect timing (pardon the pun!). Got the upper timing cover off and I'm ready to replace the camshaft adjusters. I'll post a few pictures. Looks to me like things are off a bit.
Got the upper timing cover off. Here's a few pictures and I would appreciate what people think of the camshaft adjuster positions.
Piston #1 at TDC.
Crank set a 0T.
Looking into lower section. On the right the timing chain seems REALLY CLOSE to the rod between just to the left of the chain. Maybe this is normal?
Intake camshaft adjuster.
Exhaust camshaft adjuster.
Chain seems nice and tight... but what do I know? Trying to decide if I should replace the tensioner or not. Adds a fair amount more work to the job. When I turned over the engine 2x there was no weirdness, resistance or skipping of the chain. I guess I'll do the camshaft adjusters first and see how things line up.
2013 C250 SPORT, 2014 WRX STI SEDAN, 2017 E300 4MATIC
Originally Posted by Richard Koop
Got the upper timing cover off. Here's a few pictures and I would appreciate what people think of the camshaft adjuster positions.
Intake camshaft adjuster.
Exhaust camshaft adjuster.
You camshafts are clearly off. I am a total believer in doing it while you are in there so I would do the tensioner, chain and adjusters. I didn't change mine as I did this as part of head gasket job and I did not have the parts on hand. If you have the parts better to do the extra work and not have to worry about later. The tensioner and chain have been known to fail on this engine.
Got the camshaft adjusters installed. The camshaft alignment on the top looks much better (not perfect but maybe that's too much to expect). Here's a picture of the camshaft arrows pointing directly at each other.
Everything back together tonight. Torqued the valve cover to 9 Nm and the coil packs to about the same (8 Nm). Triple checked everything all screws accounted for and in the correct place. Had to be careful because there are some bolts/screws slightly different size and they only go one place. Going to start the car tomorrow (don't want to get p*ssed off tonight in case!) and we'll see how it goes. If it starts I expected rough idle for a bit with coolant drained from the thermostat and the relearning for the ECU. But of course hopefully no rattle. Once I confirm things are good I'll take it for a long test drive.
Good luck to you sir. After you can say this was a successful repair I would like your difficulty assessment and ask if you would share the total diy expenditure. I think it would be beneficial to those that come across this thread in the future.
Also, I just replaced my valve cover seal and took some photos. Unfortunately I deleted the ones from the front. From the angle in the photo are there any warning signs I need to be cognizant of? Does everything appear to be copacetic?
Started the car tonight. Generally things went perfect except...
1. When I 1st started it had the ratttley start again - hopefully this is just because the camshaft adjusters were dry and it stopped after 1 second
2. P0016 and P0340 codes - the battery was disconnected for 4 days - so hopefully this is because of the new camshaft adjusters being installed - I'll also check the camshaft magnets and connections - people say it could be that.
All starts after that were perfect. Started about 10 times. Starts quicker and easier. Ran the car for 30 minutes. No leaks. Rev'ed up to 6000 RPM. No strange noises. Ensured coolant overflow was up to the proper level and ensured power steering fluid was at the correct level too.
So next step is cold start again after sitting for a few hours. Listening for any rattling. Tried to clear codes and they didn't clear. Hopefully they will clear on their own or I can clear tomorrow.
Tomorrow I'll do a full cold start and see what happens. I was a little upset about rattling with the 1st cold start and P0016 code but will confirm tonight and tomorrow.
Richard
Last edited by Richard Koop; Aug 28, 2019 at 07:21 PM.
After sitting for 2 days (got busy) did a full cold start tonight. Perfect start, quick and no rattle. Hopefully tomorrow get a chance to take a long drive.
Because of the P0016 I am going to remove the camshaft magnet/solenoid on the intake and ensure it's working and the connections are good. Not sure why this guy is so dressed up but I guess I'd do what he did...
Today I ensured torque good on thermostat housing (minor leak fixed), startup (perfect), warm up (no oil leaks), ensure power steering fluid is good (car jacked up front wheels off ground, steering wheel full left to right 3x), top up coolant, check adjuster magnets (good). I also changed the oil from Motomaster (ie. Canadian Tire) synthetic 0W40 to Mobil 1 0W40. I didn't change the oil too long ago but Mobil 1 seems to be the choice for this car. And because the oil is important for the camshaft adjusters I don't want to take any chances.
I have to be thorough on this one. Because what I've learned about Mercedes is everything has to be perfect. Torque, fluids, etc... For my Honda's and Nissan's... not as important.
Anyone know what small o-ring are on the front hoses on the C250? I found a small (1/2" diameter maybe) o-ring on the ground after removing and reinstalling all the hoses on the front of the engine (turbo hoses, coolant hoses, etc...). Here's a picture.
I'm thinking maybe the hose that has the red clip in this picture?
2013 C250 SPORT, 2014 WRX STI SEDAN, 2017 E300 4MATIC
Originally Posted by Richard Koop
I'm thinking maybe the hose that has the red clip in this picture?
It is definitely not from that line. That is a purge line and does not have o rings. I remember that size of o ring on the cam position sensors on the top and exhaust side of the valve cover. Check one of them.
It is definitely not from that line. That is a purge line and does not have o rings. I remember that size of o ring on the cam position sensors on the top and exhaust side of the valve cover. Check one of them.
I'll take a look but I'm pretty sure when I installed the camshaft position sensors the orings were on them.
Took the car for a good hard long drive today. Check engine light was on with P0340 and P0016 but car ran great. Here's a quick synopsis.
originally car was at the point where it took 3 or 4 times to get car to start with rattling deisel sound - it got worse over time
ordered timing kit that came with both camshaft adjusters - $400 US for the kit
ordered M271 camshaft holding kit with came with camshaft holder and wedge to release tension on the timing chain without removing the timing chain tensioner
had oil leaking into the spark plug wells so I replaced the spark plug well gaskets from this kit
timing chain looked great - no play and tensioner still worked when I put the wedge in to give me some slack on the chain to replace the camshaft adusters - so I didn't replace timing chain
replaced both camshaft adjusters from kit - everything aligned perfectly - re-torqued everything to spec
took about 10 hours of work to get to the point where I could replace the camshaft adjusters but that included a lot of pausing and reading to ensure I did things correctly
took about 3 hours to put everything back together
scale of work about a 7 out of 10 for me where changing the serpentine belt would be a 1 and replacing an alternator would be a 3
replaced oil with Mobil 1 0W40 for good measure
The car runs great now. There was a rattling sound when I started the car the 1st time after I did the work. I think it just took a second for oil to reach the new components. From then on no rattling noise or at least only a really subtle noise for a fraction of a second. Car starts immediately. Cleared engine code faults and they aren't coming back yet... hopefully never. No oil leaks or coolant leaks.
I'm still considering replacing the camshaft adjuster magnets/solenoids but probably only if things start to act up again or I get the P0016 code again.
Hope this thread helps others. Not too impressed with the quality of the C250 engine with currently only 118,000km but wasn't going to spend $6000 that Mercedes quoted me for the job. But my wife loves her car and it does drive great.
Glad to hear that you have the engine buttoned up. The wedge is not for the M271 evo engines; it was for the older M271 engines which used a different style of tensioner. On these engines, the tensioner is one-time use only.
I would pull off the valve cover and make sure you are in-time, then replace the tensioner. There have been threads started by people who have done this job and had the car come back weeks later with timing faults, and it was traced back to a re-used tensioner.
Also, when you removed the center T100 bolt, were you careful with where you placed the central valve assembly? If those were damaged in any way, they can cause strange faults.
2013 C250 SPORT, 2014 WRX STI SEDAN, 2017 E300 4MATIC
Originally Posted by The Critic
Glad to hear that you have the engine buttoned up. The wedge is not for the M271 evo engines; it was for the older M271 engines which used a different style of tensioner. On these engines, the tensioner is one-time use only.
I would pull off the valve cover and make sure you are in-time, then replace the tensioner. There have been threads started by people who have done this job and had the car come back weeks later with timing faults, and it was traced back to a re-used tensioner.
Also, when you removed the center T100 bolt, were you careful with where you placed the central valve assembly? If those were damaged in any way, they can cause strange faults.
This is the first time I am reading about the M271EVO tensioner being single use. When I changed the chain on my engine I bought a new tensioner as well but I did not reuse it after I found out about the wedge method. It is a little over 5000 miles since I did this repair and the car has not had any issues at all at least not yet.
BTW I have also seen some videos on Youtube where the tensioners have been removed and reset before being reused.
I was really careful removing the camshaft adjusters. Hopefully I didn't damage anything.
I used the wedge from the M271 kit and it gave me enough slack to remove the camshaft adjusters one at a time. I only had to push the wedge down about an inch or 2 in the middle to push back the guide rail. So I never had to remove the tensioner but did push the tensioner back about a 1/2" using the wedge. Then after I removed the wedge the guide rail moved back and the timing chain was taught again. Hopefully that's ok.
I'm driving it all week and so far no rattling sound at all. The car starts right away and idles and accelerates really well.
For good measure I am going to replace the camshaft magnets and sensors. I'll see if that makes the P0016 code go away.
If the P0016 codes persists after that I will check the timing again and maybe replace the tensioner.
I used the wedge from the M271 kit and it gave me enough slack to remove the camshaft adjusters one at a time. I only had to push the wedge down about an inch or 2 in the middle to push back the guide rail. So I never had to remove the tensioner but did push the tensioner back about a 1/2" using the wedge. Then after I removed the wedge the guide rail moved back and the timing chain was taught again. Hopefully that's ok.
Richard
Hi Richard
The issue with the newer style tensioner is that it uses an internal ratchet mechanism to prevent the tensioner collapsing even under cold start/low oil pressures (the earlier tensioner didn't have this mechanism and could be collapsed under pressure from the 'wedge'). I would expect that the tensioner in your car is now fully extended, which is why the chain appears taut, but there's probably no further extension available - which will be a problem if the chain wears (or 'stretches') further.
You can reuse the tensioner (as you might have seen on Youtube) but that requires removing it, adjusting the tensioner ratchet under pressure (such as in a vice) and reinstalling.
I recommend replacing the chain, as a minimum, if you're "in there" already, as it's only a simplex (single row) chain and is prone to stretching over time. Changing the chain isn't that hard using a split chain (you can use a cheap motorcycle chain splitter/joiner tool rather than the expensive special tool for this). Changing the tensioner isn't hard either, you just need to remove the accessory belt, remove all four alternator bolts (accessible under the car or via the wheel well) and push the alternator out of the way, then you've got clear line of sight to the tensioner using some extension bars and a socket. Note you need to use a new plug for the tensioner access hole as the existing one is destroyed by getting it out.
When I changed the chain in my C250 (at about 200,000 kms) it had stretched by about 10mm over its length compared to the new one. That's quite a bit. The chain really should have the same service interval as a timing belt in my view.
So are you saying that my 2012 C250 probably has the older style tensioner and I should replace to have the ratcheting one to prevent that timing chain noise in the future? Can I tell by looking at the new tensioner if it's the ratcheting one?
I got a tensioner with my timing chain and camshaft adjuster kit ($400 total) but I'm a little concerned of the quality of tensioner. Don't want to make it worse than the current one. I think I'll hold off for now unless the noise happens again then I'll look at replacing it.
The timing chain itself looked brand new and very taught so that's why I didn't replace it at the time. The noise at startup went away when I replaced the camshaft adjusters.
So are you saying that my 2012 C250 probably has the older style tensioner and I should replace to have the ratcheting one to prevent that timing chain noise in the future? Can I tell by looking at the new tensioner if it's the ratcheting one?
Hi Richard.
No, your C250 almost certainly has the newer style tensioner. You can tell if your new unfitted tensioner is the new style as it comes with the plunger mechanism fully depressed and locked into the body (it's released automatically when it's fitted into the engine). The new tensioner also has a spring clip around the body which holds down a small floating ratchet. Once fitted, the tensioner plunger extends (through spring pressure) as far as it can onto the chain ramp. You can't however then depress the plunger any distance without destroying the ratchet.
What I'm unsure about is how you managed to depress the tensioner using the wedge. It's possible it worked ok, but given the way the tensioner works, you can't normally use the wedge, and even the slightest easing of chain tension will release the ratchet further. That's why I think when you changed the cam adjusters it's unlikely the tensioner is in the proper working position, and I suspect it actually only worked because your chain is stretched (the photos you showed before you changed the adjusters clearly shows the cam adjuster marks pointing away from each other - a sign of chain stretch). A new chain should have both marks pointing exactly at the 12 noon position at TDC.
In your position, although it's a pain, I'd be changing the chain and tensioner myself. At least you don't have to remove the top front engine cover, just the valve cover to change the chain by itself. Virtually all M271 engines would have the original chain somewhat stretched by now (not really mileage related, more like hours of service). Anyway, just my 2 cents... 😊
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