C250cgi timing chain failure
This all started with the car taking longer and longer to start. It was first a few seconds longer and now as much as 6-8 seconds longer. I’ve read fragmented posts about gas issues, HPFP issues, fuel filter issues, and then the camshaft adjuster failures. A diagnostic chart needs to be created to help pinpoint the issue.
My particular issue does not have any check engine lights, and seems to be answered with, “this is within normal tolerance”. Anyone else have starting issues?
http://candsservice.com.au/blog/merc...ingchainissues
You might also note the tensioner can be reused - there are YouTube videos showing how to reset these (it can't be reinserted once loosened without resetting it).
Cheers, David
-what is causing premature life of the chains? I’ve seen chains with 400k miles in use and chain stretch at low miles is unusual. From what I’ve gathered, the adjuster contributes to this.
-can you test the adjuster besides pulsing it to verify activation?
-what mileage would be a good time to start checking for wear? I’ve seen various cases of delayed starting from 25k miles to 100k+ miles. This disparity is large and makes a diagnosis difficult. Profiling when members have experienced certain symptoms to when their chains have failed would help other members start taking precautionary measures.
-does our vehicle experience the crankshaft position sensor failure that has plagued earlier models?
Has anyone experienced chain stretch and/or failure and what were your symptoms leading up to this? Let’s help others start realizing that there is an issue, and how to address it. TIA.
cps failure is a past plague tbh. Very rarely will you see newer MERKS with cps issues however that doesn't mean it wont ever occur....
To answer your question, I'm not convinced that wear of chains in these engines is "premature". It is a single row chain, which isn't ideal. I think best practice should be to preventatively replace the chain and tensioner on similar intervals to a timing belt, say every 100,000km/60,000 miles.
When I changed the timing chain I left the camshaft adjusters in place as the sprockets looked as new. This is even with a chain stretched by 10mm and after 200,000km of use.
I'm not sure the adjuster magnet is responsible or not for wear on M271 EVO engines. There is a locking pin in the adjusters which can cause problems if it breaks, apparently.




I replaced my 2008 C200 timing chain at 100,00km as part of my preventative maintenance plan, I figured that the original chain would probably last 150k and at that stage the sprockets would be worn as well so I replaced only the chain and expect it to last until 200k.
There was just a momentary rattle at start up with the old chain and with the new chain no rattle at start up, the length between the chains was around 3mm so not much stretch. I am the second owner and chain the oil and filter every 10,00km.
I replaced the chain buy joining it on to the old chain and drawing it through, to replace the tensioner in my model requires removing the lower front timing chain cover I chose not to do this as I dont want oil leaks later on.
The Magnets have there own oil leak issue and do not cause timing chain stretch.
With your starting issue if it was mine I would check the air filter and replace the spark plugs if that did not work I would book it in at the dealers for scanning on the Star scanner there may well be a high pressure fuel pump or fuel sensor faulty.
To answer your question, I'm not convinced that wear of chains in these engines is "premature". It is a single row chain, which isn't ideal. I think best practice should be to preventatively replace the chain and tensioner on similar intervals to a timing belt, say every 100,000km/60,000 miles.
When I changed the timing chain I left the camshaft adjusters in place as the sprockets looked as new. This is even with a chain stretched by 10mm and after 200,000km of use.
I'm not sure the adjuster magnet is responsible or not for wear on M271 EVO engines. There is a locking pin in the adjusters which can cause problems if it breaks, apparently.
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So what are our conclusions...........??
Are the 2012 C250 4 cylinder M271 less prone to timing chain issues than earlier cars?
I sure like my updated CPO C250 coupe (but all this timing chain feedback is interfering with my sleep.
Best to all,
ez
The Best of Mercedes & AMG
cps failure is a past plague tbh. Very rarely will you see newer MERKS with cps issues however that doesn't mean it wont ever occur....
So what are our conclusions...........??
Are the 2012 C250 4 cylinder M271 less prone to timing chain issues than earlier cars?
I sure like my updated CPO C250 coupe (but all this timing chain feedback is interfering with my sleep.
Best to all,
ez
I would guess a low probability of a 60k failure...........................but it does happen............(Regret your failure, Beaver)
ez
I'm curious what happened to the cars that had this problem in the past. Did they get repaired? Did the repair last? Any other major problems? Transmission? Other parts of the drive train?
Last edited by BeaverMjr; Apr 30, 2018 at 07:38 AM.


