OM651 timing chain @76k miles, to replace or not?

Discussion in 'Engine' started by Haven't a clue!, Jul 11, 2018.

  1. Haven't a clue!

    Haven't a clue! Hardcore MB Enthusiast

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    Due to have car (w204 220 CDI) serviced at my (well respected) indie soon, conscious I'm now potentially entering higher risk mileage usage relating to potential OM651 timing chain issue.

    Effectively need to decide if I take "preventative insurance" route of having chain replaced. Like all "insurances", you never know if you'll need it unless things go wrong.

    Note: I do tend to use engine brake as its a manual(very easy/precise), so engine frequently at higher revs during anticipated braking.
    I do about 10K mileage annually.

    Yet to get quote from Indie but I'm assuming around £1k(Inc VAT).

    Had bought the car as a first M-B and long-term run-around keeper, but now beginning to wonder if time to consider p/x for a later low mileage C250.

    Any pearls of useful wisdom from fellow forum membership around:
    1- do you think this is overkill approach for mileage/usage.
    2- is there an "easier" way of accessing chain or is it engine out as per M-B practice?
    3- what else should be done at same time?
    4- anyone had similar done and therefore views on likely replacement chain cost?
    Much appreciate your useful comments.
    Regards, Tony
     
  2. OP
    OP
    Haven't a clue!

    Haven't a clue! Hardcore MB Enthusiast

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    And yes, I'm watching the game, men can multitask sometimes!
     
  3. geraldrobins

    geraldrobins Hardcore MB Enthusiast

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    If there is no sign of significant wear then leave it alone.
     
  4. CowleyStJames

    CowleyStJames Hardcore MB Enthusiast

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    My last C class with OM651 engine, got to 183,000 with no major issues and never experienced timing chain slap, rattle or failure.
    It was still running as sweet as it was at 41,000.
     
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  5. OP
    OP
    Haven't a clue!

    Haven't a clue! Hardcore MB Enthusiast

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    If it gives advance warning then I agree. As said, considering as preventive insurance, maybe
    <£1k Vs >£3k?

    Just reading MB-World thread, implies any rattle more evident after oil/filter change, so that will happen next months service, then able to best assess.
     
  6. OP
    OP
    Haven't a clue!

    Haven't a clue! Hardcore MB Enthusiast

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    Well, further reading on MB-Owners(not M-B World) and USA sprinter-source.com forums gleans supplementary info/hearsay along lines of:
    1- Issues with both OM651 injectors, chain tensioners & chains recognised by M-B well before 2013 (my model year) due to warranty claims during 2009-2011 period), this caused revision/sourcing of M-B parts fitted.
    2- potential chain issue CAN often be heard well before failure, particularly just after oil/filter refresh.
    3- regular oil/filter refresh reduces occurrence risk.
    4- not using the stop/start function likely reduces occurrence risk.
    5- early replacement of tensioners is cheaper risk reduction option.

    Reassured by various posters indicating high mileage being achieved, based on which I'm veering towards
    1-continuing scheduled servicing with good quality oil/filter changes, with audio check afterwards.
    2- minimal use of stop-start.
    3- consider replacing tensioners around 100k.
    Still most interested to hear if able to replace chain in-situ.
     
  7. gianton

    gianton Hardcore MB Enthusiast

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    It can be done...



    Engine out needed only if you have to replace the guides.
     
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  8. pembssurf

    pembssurf Hardcore MB Enthusiast

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    Think your safe with facelift 2013 models. Bearing in mind there are more OM651 engines on the roads than any other diesel Merc. Virtually every Vito van for starters. If you search hard enough you will always find a few occurrences of every fault imaginable. No where near as prevalent a failure as the M271 engines.
     
  9. BTB 500

    BTB 500 MB Club Veteran

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    Easy perhaps, but routinely using £15,000+ of engine and transmission to slow a car down rather than a few hundred pounds worth of brake pads and disks never struck me as a great idea :dk:

    Also with a RWD car engine braking acts solely on the back wheels, which have less grip when decelerating. In an extreme case (wet or slippery road) downshifting could break traction at the rear ... ABS and ESP can't save you from swapping ends then (as they relying applying/releasing the brakes). There are good reasons why brakes are strongly biased to the front.

    The only time I'd use engine braking would be to prevent speed buildup on a long descent. Riding the brakes there is likely to result in them overheating.

    As they say in the States though, YMMV :)

    Oh and like the others I'd be inclined to leave the chain alone unless you have any symptoms of wear!
     
  10. OP
    OP
    Haven't a clue!

    Haven't a clue! Hardcore MB Enthusiast

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    "slow a car down rather than a few hundred pounds worth of brake pads and disks never struck me as a great idea."

    Valid point and one that I am more consciously now considering, agree less strain on the chain!

    Frankly the more I research on this and other forums the less of an issue the OM651 chain issue seems to be, excepting earlier pre-2010 models before M-B took some preventative build action.

    Maybe another Urban Myth this thread will rebalance.
    Cheers, Tony
     
  11. gianton

    gianton Hardcore MB Enthusiast

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    My car ('13 C250 CDI with the OM651 engine) has 174k miles and have no signs of chain rattle. I never use the start/stop feature and change the engine oil every 5-6k miles with good quality oil (Fuchs Titan GT1 PRO C-3 5W-30). I consider changing the chain tensioner at about 200-220k miles as a precaution.
     
  12. stephenmercedes

    stephenmercedes Hardcore MB Enthusiast

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    Easy for anyone here to advise you to change the chain, but it's not our money! I would agree with consensus so far in that if there are no impending doom symptoms, leave well alone...
     
  13. BristolMike

    BristolMike New Member

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    I wrote to Mercedes-Benz UK Limited about this matter and the CEO's office replied on 16th November 2016. They could have used some none committal "weasel words", but instead they chose to pin their colours firmly to the mast in no uncertain way and wrote as follows:

    "As long as the car is serviced and maintained within manufacturing guidelines, as you have pointed out in your letter, then please rest assured, your timing chain is designed to last the lifetime of the engine". Later in their letter they added "To put it simply, as your car is not affected by the recall, we are confident there are no real concerns and the possibility of a failure of the timing mechanism on your car would be unlikely. I do hope the information provided has alleviated your remaining concerns and has reassured you in the reliability of your Mercedes Benz C Class".

    Thus far I have driven this car for 61,000 miles, over almost 6 years, and to-date it has proved to be totally reliable apart from a broken coil spring, which was the fault of the poor state of road repairs in Cornwall.
     
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  14. Gazwould

    Gazwould Hardcore MB Enthusiast

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    No manufacturer will ever admit an issue .

    Even if it's blatantly an obvious poor engineering as such is the VAG 2.0 TDI 77mm oil pump drive that is still goosing turbos and seizing engines to this very day .

    And a recall in one country doesn't mean a thing for others .
     
  15. stephenmercedes

    stephenmercedes Hardcore MB Enthusiast

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    Indeed, and in this country, to kick a manufacturer up the **** you need to get BBCs 'Watchdog' involved...
     
  16. BlackC55

    BlackC55 Authorised Forum Sponsor Authorised Forum Sponsor

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    We have done many of these chains. On one of my own cars too. I run 3 cars with the 651 engine. Two are on 170k and one on 215k. Do the chain when it needs it. When you have a slight rattle at cold start get it replaced. Up to that point don't worry about it. Just make sure the oil level is good and its serviced on time.
    I look after a 651 engine car with 400k on it with the original chain and its still quiet.
     
  17. BristolMike

    BristolMike New Member

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    Perhaps I didn't make clear, but the usefulness of such a letter is that the foundation of any successful legal claim would need to establish, before progressing further, what could reasonably be expected of a timing chain in a Mercedes Benz OEM651 engine. This letter avoids any need for a complainant to make that argument successfully, with the attendant need for evidence; expert engineering opinions etc, which can be expensive and sometimes contradictory.

    What MB appear to have done (perhaps inadvertently) is made unequivocally clear, what they (and therefore any customer can) expect of the timing chain in a properly serviced engine. It is THEIR opinion that a timing chain (properly serviced) was designed by them to "last the lifetime of the engine". This is no small matter with engines lasting 400,000 miles and more.
     

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