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6.3 M156 head bolts killing engines in droves! C*bblers I say...

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by growla666, Feb 20, 2017.

  1. growla666

    growla666 Senior Member

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    There's a lot opinion about head bolt problems on 6.3 M156 engines but from what I can see no one has hard facts on the volume of cars affected by it. A quick check on how many left shows over 85% of CL63s are still roadgoing, likewise for ML63s, S63s, C63s and CLS 63s and a look on auto trader shows at least 2-3 63 engined variants (mostly MLS admittedly) have done over 120000 miles,so yes, head bolt problems exist but not to the extent some forum owners imply. Other cars of similar types e.g. M6 are declining in use in a similar fashion ( by about 15% over ten years).....according to DVLA so is it really that wide spread? Before anyone suggests it's a big deal there are over 3600 registered C63s and I can't find hundreds of owners bitching, maybe 10-20 odd and most on US websites. Thoughts?
     
    Last edited: Feb 20, 2017
  2. Craiglxviii

    Craiglxviii Senior Member

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    I will look on some lists you don't have access to this week and see. Thoughts are it's under 3% of production volume, that's around the magic number for quality issues to be missed in design development.
     
  3. OP
    growla666

    growla666 Senior Member

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    Yes that be interesting Craig, still waiting for engineers report on the cl63 am
    About to buy so any numbers like would be helpful. What Lists are these then? Dealer lists? Btw at what mileage did you change your auto box fluid?
     
  4. Craiglxviii

    Craiglxviii Senior Member

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    On the 215 it was done (astonishingly, considering everything else that wasn't!) at 87k and again at 122k.

    The lists I have access to are a series of quality reports by OEMs, customer complaints if you like. Some only have a few words detailing the issue and some go into great detail. My suspicion with this is that the head bolts are considered like ABC, a few bad ones combined with lack of care has soured peoples' attitudes.

    Watch this space and I'll see what I can pull up.
     
  5. AMGeed

    AMGeed Senior Member

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    The faliure rate is rare, but worth mentioning if your engine falls in the range below number 050580. Whether you take measures to replace them or not is a personal decision.
    I believe MSL can replace them one at a time without the need to replace the head gasket which should reduce the cost of labour a lot.

    I'd buy the car and enjoy it. Life is too short to worry about what may or may not happen.
     
  6. Submariner1

    Submariner1 Senior Member

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    I think there are 4 points to this.
    1. Mercedes wouldnt have a proceedure to cure the fault and a replacement part if it was not significant enough to merit it.
    2. This was the first engine built from the ground up by AMG. With their knowledge the engine should have been the best ever. It must have been disaterously embarrassing for them. Unoess it was prevalent enough this would have got buried for sure.
    3. The main point like the Lotto Advert. "It could be you"
    4. How deep is your wallet. I.e. If you paid £27K for a nice 63 and coolant leaked or the cam buckets died do you have up to £10K to put it right? and it doesnt bother you.?

    I dont so would not.

    During my trainiing as a Chartered Accountant, one thing struck me. It was a taxation tutorial, where the Professor said there is only one form of income the Inland revenue do not want a slice of .... its gambling! Why because they worked out that clearly people loose mor ethan they win. If they taxed winnings they would have to allow losses!
    To put it into context, at that time Prostitution was illegal, yet the Inland Revenue still assessed and taxed their earnings.
    And yes thats is a fact, as a junior account I remember well, a rather delicate matter where an extremely up market, terribly refined, lady requested an appointment to regularise her tax. It took about 10 minutes before I realised where her income came from. She just didnt look the type.
    Lesson learnt I dont gamble.

    That said I know three 63 engined owners who must have had two sets of "affected engines" and had no issues and were oblivious to the matter. So thats 6 affected cars .
    They are now on the new engines, which are unaffected. All were leased/owned for three years ... not terribly high mileage I would guess all their cars were upgraded sub 40K miles.
    But I have recently met one S63 owner who had a slight coolant loss, topped it up and then had a leak at 58K miles. His did not go internal, and he did it himself. And he changed the ARP head bolts or something, and the cam buckets.

    So that is 1 in 7 I have met. So approx 14%. Naturally this sample is far too low to extrapolate any meaningful inference from it. But far too high for me to gamble with.
     
  7. daveenty

    daveenty Senior Member

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    But no-one could possibly have these figures as the majority will have been repaired outside the dealer network. Let's face it, they started production in 2006 and most people outside of forums still aren't aware of it. Therefore, if you have a 5 - 10 year old car and it starts losing water, it would probably go to an independent and not a main dealer

    The majority of M156 engined cars which have disappeared won't have done so because the engine gave up though, this would more than likely have been repaired/replaced. I'd suggest that the non-existent ones would have been written off due to a dose of over exuberance on the part of the driver.

    It's a real problem and one which Mercedes recognised and changed the design accordingly. The previous use of stretch bolts which was causing the issue is no longer in practice, so the engines are now good, but there are lots of people all over the world who have suffered with both the head bolt and cam bucket failure, all of which is well documented.
     
  8. OP
    growla666

    growla666 Senior Member

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    So my take on the responses so far are - some people have a v low risk threshold and won't touch a car if there's any possibility of expensive engine failure and can't reasonably mitigate it ( through warranties - ironically none of them do aside merc's original manufacturer warranty). I'm of this camp unfortunately. Thing is "I wants it bad" that cl63.

    Some cars have had repairs (but no knows how many but Clive believes it's 3% of 63 engines) which will still be expensive to repair even outside main dealers - e.g. MSL charge £3800 to replace the bolts and buckets with Weiser Arps. That's 20% of the cars cost! I'm all for preventative maintenance but that's serious money. Still would give complete peace of mind. My car engineer guy from Scotia Vehicle Repairs suggests leave it until something goes wrong.

    Up until 2010 Q4 2623 M156 engined Mecs were registered so 3% of them equates to under 80 vehicles in total. Even if it's closer to Submariners more pessimistic 14% that's 367 cars, ok more worrying so let's split the difference and call it 222 cars - still less than 10%.

    In summary buying a pre 2010 CL63 has 1/10 chance that it could be hugely expensive. Most bookies would take 10-1 odds all day long. Statistically the odds remain low so is it an age thing or mileage thing? People aren't sure. I can buy a warranty that will cover some,but not all, the costs of a bolt snapping. Should I just forget it and get a 5.5 litre CL500 instead? Nice one in Worksop!
     
  9. V6Matty

    V6Matty Senior Member

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    If the CL your looking at is above number 050580 then your in the clear and you should just enjoy the car, if it falls below that number then it's always going to be a risk, you will probably be fine but you have to fastidiously check levels and have things changed should there be a problem.
     
  10. John Laidlaw

    John Laidlaw Senior Member

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  11. V6Matty

    V6Matty Senior Member

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    hmm good point John, now you've said that I'm not sure.
     
  12. Craiglxviii

    Craiglxviii Senior Member

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    Right. Thanks to the fandabedozee system at work I have finally been able to get the list I wanted downloaded. Watch this space.
     
  13. Craiglxviii

    Craiglxviii Senior Member

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    OK. A few caveats, I cannot give specific year details or model details here.

    Right. So, AMG have consistently built almost exactly the same number of 6.2 V8 engines engines per year since the M156 debuted in 2007. That number is, astonishingly... 1800.

    So there have been, total, 16,200 engines built. Of those the stretch bolts issue affected around 7,200 engines.

    I was able to find 97 cases relating to these where MB have recorded cylinder head bolt failure of any kind. NB this doesn't limit the issue to MB-only repairs, it also takes into account where independents have reported the problem to MB. It's reasonable to assume that this accounts for 3/4 of all cases as the report is always a claim for MB contribution to the repair bill.

    So the 97 customer issues reported comes in at (97/7200) = 1.35% of production. Throw in another 25% on top and we get 1.7% of production, just under one in fifty.
     
  14. AMGeed

    AMGeed Senior Member

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  15. Submariner1

    Submariner1 Senior Member

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    I too, was told its after engine no ending 60658 and you are OK.
     
  16. Andrew Roethel

    Andrew Roethel New Registration

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    Joined just so I could post about this issue I have a 2008 C63 the head bolts failed 2 years ago at 57000km. [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    The problem is poor engineering a simple cross section of the old bolt and new bolt shows why they fail

    [​IMG]

    Here's what your in for once they snap.

    [​IMG]
     
    Last edited: Apr 17, 2018
  17. John Laidlaw

    John Laidlaw Senior Member

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    Nice to see (or not if you are the one with the issue ) the end result.
    Is your car still alive?
     

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