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MTU 12V 2000 M94 Cylinder Head Gasket Failure

Discussion in 'Engines' started by T.K., Dec 7, 2020.

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  1. T.K.

    T.K. Senior Member

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    Gentlemen .... good evening,

    Three cylinder head gaskets in the same cylinder bank on a 2016 MTU 12V 2000 M94 engine failed which led to a severe oil leak as seen in the image below. The engine has 800 operating hours. The engine diagnostic data which was read by the local MTU dealer showed no engine overheating and no engine overload which are usually the reasons behind the failure of cylinder head gaskets. The local dealer is unable to explain the cause of the failure.

    The cylinder head was dismantled and traces of mild corrosion were seen on the cylinder head gaskets and on the surface of the engine block as seen in the attached images.

    I would appreciate hearing from anyone who has experienced or heard of a similar failure and can explain to me the cause of such an unusual failure.

    Thank you.

    SL86-656 Cylinder Head Oil Leak (1).jpg SL86-656 Cylinder Head Oil Leak (2).jpg SL86-656 Cylinder Head Oil Leak (3).jpg
  2. NYCAP123

    NYCAP123 Senior Member

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    My guess would be not torqueing down the bolts properly.
  3. T.K.

    T.K. Senior Member

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    That was my theory and argument as well, but is that possible on a factory assembled engine?
  4. mapism

    mapism Senior Member

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    It would have been a good idea to check that before unbolting the heads.
    I appreciate that if they were directly pulled without doing it, now my suggestion is useless.
    But possibly worth considering for the rest, other engine included.
  5. Beau

    Beau Senior Member

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    So this has the makings of an educational thread for me. Does it make sense to check the torque on the other heads that may remain in place? Just as an indicator if they are also found deficient.
  6. NYCAP123

    NYCAP123 Senior Member

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    It would make absolute sense given the circumstances. In fact it would make sense for everyone to do but I've never heard of it happening. I doubt there's any claim to be made on this, but it should serve as a lesson to all to not just live with oil leaks. Had the gasket been changed when the leak first developed that probably would have been the extent of the damage.
  7. mapism

    mapism Senior Member

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    Yup, it's reasonable to assume that, but as the old saying goes, hindsight is a great thing...
    Pretty sure what happened here is not something anyone would expect from such engine beasts - let alone a 4 years old one with just 800 hours!
    And even if as I recall they have single cylinder heads, it ain't a trivial job.
  8. NYCAP123

    NYCAP123 Senior Member

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    Exactly. As I said it'd be smart for every owner to torque down every bold (and so would be wearing suspenders with your belt) but I've never seen it happen. I don't think an oil leak in 4 years or 800 hours is unusual. It could be from a bolt not torqued down enough or excessive vibration due to something being wrapped on the prop or.... or it could be just a bad gasket or.... That's why that pre-cruise engine room check is so important.
  9. T.K.

    T.K. Senior Member

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    Thank you Gentlemen for your feedback. Incorrect torque settings of the cylinder head bolts is the only logical cause behind this failure. However, it is not a standard procedure or part of the engine preventive maintenance checks to re-torque the cylinder head bolts especially on a relatively new engine with only 800 operating hours. It also not something anyone would expect on a modern 12V MTU engine. It is a very frustrating failure, especially that it is extremely difficult to address it as a warranty claim after 4 years.
  10. T.K.

    T.K. Senior Member

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    The local MTU dealer has removed all 12 cylinder heads and all 12 gaskets will be replaced.
  11. T.K.

    T.K. Senior Member

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    Your suggestion is correct and I also mentioned it to the MTU mechanic but unfortunately he had already removed the cylinder heads. It would have been an extremely useful check to confirm if any of the cylinder head bolts were indeed loose.
  12. Capt J

    Capt J Senior Member

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    Check the deck of the block and make sure it’s straight. It sure seeems like that ring area in the second photo is raised higher than the rest of the block. Could the engine have gotten really cold at some point in time?
  13. NYCAP123

    NYCAP123 Senior Member

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    Yep. Bet there'll be a lot of guys buying torque wrenches after today, especially those who've been looking at oil leaks thinking they're not that bad yet.
  14. T.K.

    T.K. Senior Member

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    Capt. J, what do you mean with an engine "getting cold"? If you a referring to freezing temperatures, in our part of the world it is never cold. Even winter temperatures are relatively high. Night time winter temperatures are never less than 60 degF.
  15. Beau

    Beau Senior Member

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    I was thinking more in the way of a test. If the adjacent heads aren't torqued properly wouldn't that give even more credence to the suspected cause you are all discussing.

    If there isn't any factory liability, the OP should check his insurance policy to learn if it covers these types of unforced failures.

    T.K. have you owned the boat since new? Is it possible it froze prior to your ownership?
  16. Beau

    Beau Senior Member

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    My Mans had to be retorqued, I think it was at 400 hours?
  17. T.K.

    T.K. Senior Member

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    All 12 cylinder heads on the port engine have already been removed. I will have the starboard engine cylinder heads re-torqued which isn't suffering from any oil leaks but could show the same symptoms at a later stage if head torque is the problem.

    The insurance will cover the failure and repair costs.

    I purchased the yacht new in 2016. I took delivery of it in Italy in March of 2016. The only time it could have been subjected to any cold temperatures is at the shipyard before I took delivery of the yacht but I doubt that winter temperatures in Italy in the north Mediterranean region reach freezing levels.
  18. mapism

    mapism Senior Member

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    Mmm...
    That chap should have thought to do that regardless of your suggestion.
    It's his job, not yours.
    I can only think of two possible reasons why he didn't, but neither come out in his favor:
    1) lack of competence;
    2) guilty conscience.

    Ref. 2, does MTU possibly prescribe a re-tightening of new engines after the first X hours (50, 100, or whatever)?
    If yes, AND they always did the maintenance for you, AND they forgot to do that, I would smell a rat.
    Mind, I'm not sure if that's something included in MTU maintenance echelon for new engines.
    Maybe someone else can confirm - or not, as appropriate.
  19. mapism

    mapism Senior Member

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    Interesting.
    Do you possibly remember if that was part of standard MAN maintenance routine, or if it was an initiative of your mechanic?
  20. mapism

    mapism Senior Member

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    If correct, that would be the most impressive diagnosis ever made just upon photographic evidence! o_O