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Hey guys,
I hope everyone is safe and healthy. My wife's 2010 GLK 350 is due for a timing chain replacement. Do we have any available procedures/processes for the M272 engine? Has anyone completed a timing chain project with pictures? I have seen multiple parts displayed on websites but some include cam sprockets and oil pump drive chain too. I can see replacing the crankshaft drive sprocket. What are you guys thoughts? Thanks, Bo
 

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Hey guys,
I hope everyone is safe and healthy. My wife's 2010 GLK 350 is due for a timing chain replacement. Do we have any available procedures/processes for the M272 engine? Has anyone completed a timing chain project with pictures? I have seen multiple parts displayed on websites but some include cam sprockets and oil pump drive chain too. I can see replacing the crankshaft drive sprocket. What are you guys thoughts? Thanks, Bo
Hey guys,
I hope everyone is safe and healthy. My wife's 2010 GLK 350 is due for a timing chain replacement. Do we have any available procedures/processes for the M272 engine? Has anyone completed a timing chain project with pictures? I have seen multiple parts displayed on websites but some include cam sprockets and oil pump drive chain too. I can see replacing the crankshaft drive sprocket. What are you guys thoughts? Thanks, Bo
I have a GLK 350 with 88000 miles . Have you ever heard the expression " If it Ain't broke dont fix it " ? There is no such thing as due for a timing chain replacement unless its actually broken but of course the dealer would love to have you think so. This is my 9th Mercedes and I also have a 1980 450 SL with 122,000 miles that I bought new . I am not a mechanic but I simply look up how to fix on youtube and shop for parts on Amazon . Save your money ! If you insist on using your dealer just wait until it breaks, ( it may never break ) its the same price except for the tow and you can use your AAA card for that . Your Welcome , Al
 

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Before letting it run until it breaks, my question is: Is this the type of motor that bends valves when the chain breaks? I'd assume so since most, if not all, higher compression engines are.
My guess is the chain will not break, but stretch to the point the adjuster can no longer adjust for it. After all, overhead cam engines have very long chains and the longer they are the more stretch you end up with. At the point it can no longer adj for it'll just get looser and looser and louder and louder. Being loose it's vulnerable to jumping a tooth. When a cam chain jumps a tooth it throws the cam timing way out of whack and the engine will lose power, and in some cases bend valves. Ever see a motorcycle going down the road and the chain on the bottom is flopping around and you think; "how is that even staying on?" Luck is the answer, but it doesn't hurt a bike if it merely jumps teeth, only if it falls off...
When you turn off an eng it will often rotate backwards slightly before stopping, and that moment gives that slack a chance to flip up and over the teeth. Picture how you'd whip a garden hose to get it to settle correctly, the chain whips up and over the teeth. This eng may have guides around the sprockets to prevent this, I haven't looked, but the point is that flipping of a loose chain is how it jumps a tooth and the chain tensioners are to prevent that and of course help keep it quiet. Also, a stretched chain is no longer matched to the teeth so wear accelerates, which causes more stretching, etc. So when you hear or know the adjuster is out of adjustment you should most certainly replace the chain(s).
So I guess I'd read up on when they typically stretch too much and/or listen for chain noise. My guess, based on newer cars I've had with chains, is it's worry free for long after 100k miles, probably <200k, but each car/engine is different. Older cars I've had, like US made stuff in the 80's or older, the chain is a real issue. Many even had plastic gear teeth which was an idiot idea and very short lived, but either way the chains all stretched and despite being extremely short chains, it was very common to jump a tooth. The fix was to buy a real chain/sprocket set that is made more like todays and the problem was solved.
Lastly, a stretched chain also means your cam timing is retarded, and since they start stretching the moment you drive it off the lot it simply gets worse over time. This cause low end power to drop and extends your high rpm power band, but if you have a rev limiter then you never see that so you simply lose low end power. At what point that loss bothers you is up to you, but many people either adjust the gears or replace the chain just to gain back that power. Or in my case I often advance it a bit from the start to somewhat counter stretching.
TMI but better more than too little ;)
 

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This answer is for Bomab who was contemplating changing a timing chain before it breaks and my answer was if it ain't broke don't change it . Since most of us are Monday morning mechanics allow me to expand on that a little.
The timing chain is an internal component and should not be changed unless the engine goes bad....You have to dismantle the engine to change it. It should not wear under normal use...just like you would not change the pistons as a maintenance job....
Wait until ~ 400,000 kms to think about that timing chain work.. and here is another previous post that may help .



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mocab180
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B180 CDI Sport 6sp '09
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#3 Aug 5, 2018
Yeah, timing chain doesn't have a change interval. It's a car life time item ( aka warranty period). You change the timing chain when it's starts rattling. You can notice this noise on cold starts. Always when you replace the timing chain Buy the OEM raplacment set. ( Mercedes parts)



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forrera
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A180 CVT, A170, A190, B200
Joined Jan 22, 2012
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#4 Aug 5, 2018
Timing chain will need checking/replacing if you encounter loud rattle when starting the engine, especially when cold.
Also stretched timing chain makes a specific sound when the engine is running and warm. Sounds like a kind of a mill.
In extreme cases you'll have EML on with fault code P0016, because the signals from the crankshaft and camshaft position sensors and not correlated. You might also notice the engine cranks a bit longer before firing.
Timing chain tend to stretch in certain models more than others, and also depending on frequency of maintenance.
 
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