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C250 CGI Timing Chain

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by dan ennis, Dec 14, 2017.

  1. dan ennis

    dan ennis Member

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    Hi all

    My first post as a Mercedes owner. I am after peoples opinions of the state of my timing chain/gears on my m271 evo, I will explain further when a few opinions come in as to why I ask! The chain has a fair bit of movement in it on the right hand side and it is noisy when running.

    Thanks

    IMG_20171214_160247.jpg IMG_20171214_160209.jpg IMG_20171214_160109.jpg

     
  2. Arudge

    Arudge Senior Member

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    How many miles? Have you, can you, remove the tensioner and establish how far out it is? The tensioner, certainly on my W208, only comes out so far, then the chain goes slack, just like yours.
     
  3. phillj

    phillj Senior Member

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    A classic example of a common problem on the M271 engine worn sprocket teeth & a slack chain (drive no further as the chain may jump the teeth resulting in valve damage) an issue well documented on this forum get it fixed asap:(
     
  4. OP
    dan ennis

    dan ennis Member

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    Would it surprise you if I told you the photos are of a newly replaced chain and sprockets? The car has 55k on it, I got it "repaired" as a suspected chain/sprocket issue as I had an engine rattle and engine fault codes. There is quite a story attached to all of this but I just wanted to get peoples opinions before I started throwing blame around!
     
  5. Arudge

    Arudge Senior Member

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    Yes it would surprise me. Both the chain and the sprocket are oil stained and i would not expect that on new parts, not yet anyway. The staining is the oil being burnt on by engine heat but it takes some time to build up.

    The next step is to look closely at the mating parts of both the chain and the sprocket, even the tiniest of wear steps is indicative of long service. See if you can get am image using a small mirror of the underside of the chain, clean the chain first if you can.
     
  6. OP
    dan ennis

    dan ennis Member

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    So this is the story. I had a company who specialise in manufacturing replacement chains and sprockets (used by quite a few people on the forums) carry out the job of supplying the parts and carrying out the diagnosis and repair. The mechanic initially "replaced" the chain, sprockets and tensioner and after doing so said that there was another issue with the engine and it was making a clicking sound on turning the engine by hand and he was reluctant to start it. This service was carried out at my home address and he gave up when it got dark and said he would be prepared to return and diagnose the issue further.

    After chasing the mechanic and owner of the company for two weeks he came back and within an hour, delivered the bad news that the big end was gone!! I had to go to the hospital and whilst out, he had got my girlfriend to start the car up and it had apparently run ok for a minute and then made a nasty sound. So after the bad news, he left us with an apparently knackered car.

    I thought this a bit odd, even more so when the owner of the company rang a few hours later offering to buy the car from me (£3k under value) as he felt bad for me. So today I took a chance and drove it round to my regular mechanic who is 2 minutes away from my house. The car made it there fine and was just a little louder than normal, no big end noises. We put a stethoscope on the engine and the bottom end is quiet as a mouse, the only noise (the loud rattling noise) is coming from the timing chain. As you can see, this all seems a bit fishy.
     
  7. star

    star Forum Supporter Authorised Forum Supporter

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    I replaced a chain on that model today, only 70k miles and took that exact same video for customer. No noticeable wear on sprockets, (compared them to new ones).
     
  8. star

    star Forum Supporter Authorised Forum Supporter

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    Some of these gears are not remanufactured correctly and can rattle badly.
     
  9. OP
    dan ennis

    dan ennis Member

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    Interesting, so this video is of the supposedly finished job! It seems really odd the lengths they have gone to not to accept any liability. The mechanic said the same, very little wear on the sprockets. Out of interest, do you always replace with MB genuine sprockets?
     
  10. Arudge

    Arudge Senior Member

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    Those sprockets are not new. I've just enlarged one of the images and there is a clear wear step on the inlet cam. Immediately above 'ein' on the far side of the teeth, the wear line can be clearly seen.

    I think you've been done mate.
     
  11. Arudge

    Arudge Senior Member

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    How to you re-manufacture a sprocket without reducing it's diameter or welding every tooth?
     
  12. star

    star Forum Supporter Authorised Forum Supporter

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    Yes on this model, expensive but then we don’t get any problems. They are just coming they on mb exchange program. So cheaper. Finished job??? Surely that’s the old chain and slipper guides.

    After we replaced the chain only, it didn’t ride off the sprockets, customer was advised about sprockets but it would add close to £1000 to the job.
     
  13. star

    star Forum Supporter Authorised Forum Supporter

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    I think they make new gears and re use the internals. We only use mb sprockets for the later type chain, the earlier 271 engine, we offer the choice due to the value of the car and cost of oe parts but have learnt to inspect for correct assembly.
     
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  14. OP
    dan ennis

    dan ennis Member

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    So do you think it is more a chain issue on this model than the sprockets? Apparently the chain should be new, i'm not convinced obviously. So far I am £1000 out of pocket and currently have a hire car so i'm not happy! I will try and pm the supplier to you, i'm sure you will know who they are.
     
  15. star

    star Forum Supporter Authorised Forum Supporter

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    As said earlier, we only use mb gears on this model engine, in your case, those gears aren’t new and definitely need replacing looking at the visable wear.
     
  16. OP
    dan ennis

    dan ennis Member

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    I think you are right!
     
  17. Arudge

    Arudge Senior Member

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    Understood, thank you. Mine looked like sintered steel but the OP's was flame hardened steel, not much you can do with a flame hardened piece once it's been 'cooked'!!
     
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  18. Arudge

    Arudge Senior Member

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    The best I could do I'm afraid. But the wear step can be seen clearly. 20171214_215237.jpg
     
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  19. OP
    dan ennis

    dan ennis Member

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    Thank you, the more evidence, the better.
     
  20. LostKiwi

    LostKiwi Senior Member

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    That's definitely done some miles. No question.
     

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