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misterious Oil Leak from over starter - Mercedes S class 320 CDI (W221 - 642.930) 2007

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Hristo R., Mar 14, 2019.

  1. Hristo R.

    Hristo R. New Member

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    Your Mercedes:
    Mercedes S Class CDI 320 (W221 - 221.930)
    Hi Guys,

    I bought a Mercedes S class 320 CDI (W221 - 642.930) 2007, with full service history mainly from MB and in good condition and for a year had no problem at all with it. Mileage is not too high for the year just about 102 000miles.

    All of a sudden now, I have an oil leak which appeared right after I had my car for an MOT test, which having in mind everything was fine with the car before the MOT test is very peculiar that it appeared in the day of the MOT test.
    It was for my big surpice when the MOT tester found the car was leaking and I had not observed oil spots before that day and on the way back home the car was already making a small but easily noticable oil thread behind it, which was not the case in the morning before the MOT test.
    The only thing the garage had to do on the car that day was to change the front tyre before the test as the one I had was a bit worn, so I asked them to do that.

    I would not return my car to the same garage for help with the oil leak, as I just went to them as they were the only free garage to do MOT on one day notice, and reading reviews for them now they do dodgy things there, and I just wanted to use them for MOT, wouldn't trust them for more or to admit they could have accidentally (or deliberately) caused the oil leak, and I still have in mind there is some chance the issue was there but concealed by the plastic cover which protects the engine from dust. However I should have noticed oil traces if that was the case in previous days/weeks which I have not.

    My question to my more experienced forum fellows and mercedes specialists here is, what could be the reason for a leak which appears to be coming from above the starter?
    I have completely removed the under-engine-cover and have tracked the leak produces an oily spot of about 5-10cm in diameter and usually is observed after the engine is stopped and not during running engine.
    To potentially excude the Turbine from the equiasion, recently I had a full service and air filters were changed and turbine was accessible to be externally inspected, it did not have extensive amount of oil on it, so it does not seem to be the turbine, but must be something under it and above the starter.
    Also the oil is engine oil for sure (black in colour).

    Any ideas would be highly appreciated. I am trying to reserve an appointment at reputable garage or MB next week, so would be good to know, to avoid unnecessary work. The MOT garage asked me if I wanted them to inspect the leak on the day of MOT for which I paid them £40 and after inspection they suggested they wanted to replace turbo air hose and reseal the oil pan, which does not make sence when the leak comes from above the starter and above the oil pan seal, so although I know it is a common issue with this engine, no point of spending £800-£1000 for that to only realise problem is from above.

    Any advise would be highly appreciated!

    Great thanks fellows! Buying a pint to everyone that helps with the right directions :)
     
    Last edited: Mar 14, 2019
  2. malcolm210

    malcolm210 Senior Member

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    Assuming the garage didn’t cause the leak in some way the main suspect will be the oil cooler seals, they are a very common failure on the OM642 engine indicated by oil dripping down from the vee and appearing at the rear of the block. Do a search on Utube for OM642 oil cooler seal failure and all will be revealed, MB have revised the original orange coloured seals in favour of purple Viton items to remedy the situation still an expensive fix though as the labour to get to them is circa £600
     
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  3. JBell

    JBell Senior Member

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    Your Mercedes:
    C350 CDi Estate (GAD Edition)
    As above, Oil Cooler seals, if the oil is at the rear of the engine

    Where are you based?
     
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  4. star

    star Forum Supporter Authorised Forum Supporter

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    Smart + others :)
    Sadly very common, did 3 sets last week. Nothing the garage could have done to cause these to leak.
     
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  5. Doug1234

    Doug1234 Senior Member

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    Your Mercedes:
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    Have a look at this
     
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  6. OP
    Hristo R.

    Hristo R. New Member

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    Mercedes S Class CDI 320 (W221 - 221.930)
    Hi Mate,
    I am based in Walton-on-Thames, Surrey, KT12
     
    Last edited: Mar 14, 2019
  7. OP
    Hristo R.

    Hristo R. New Member

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    Your Mercedes:
    Mercedes S Class CDI 320 (W221 - 221.930)
    Great thanks for your reply mate. Reading is not too far away from where I live. Could you give me a quote how much would it cost to fix in your service and could the job be done within one day or normally how long does it take?

    Also is it worthy doing other bits when doing this work, having in mind intake manifolds and turbo getting detached/cleaned, could some other seals/o-rings be replaced as well or anything you would do if it was your car [apart from throwing it away like some friends are "advising" me] :)?

    Great thanks!
     
    Last edited: Mar 15, 2019
  8. star

    star Forum Supporter Authorised Forum Supporter

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    Ok will pm an estimate later today to include oil cooler as well, normally the job is completed in a day but allow two just in case there’s any siezed bolts. The only extra part which may need replacing while your there would be the inlet port motor, if it’s contaminated with oil or not. The manifolds do wear but there’s a work around that due to cost, approx £700 each iirc.
     
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  9. OP
    Hristo R.

    Hristo R. New Member

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    Great thanks, yes please PM me with the estimate including the parts (e.g. inlet port motor, any other gaskets, seals, o-rings you would recommend replacing as a good practise while getting to the oil cooler.

    Best Regards.
     
  10. OP
    Hristo R.

    Hristo R. New Member

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    Mercedes S Class CDI 320 (W221 - 221.930)
    Hi Guys,

    Perhaps I have misled you a bit with my initial assumption the leak was coming from above the starter.
    After having a better check to take a few images of the leak as well, it seems it is probably more accurately to say it is coming from just above the higher oil pan. Like on the below images on both sides. Also in the connection cavity between the Engine and transmission there is some oil as well.

    Do you still think this is the OIL cooler or could that be coming from the rear crankshaft seal?
    Or could that be coming from the higher oil pan sealant?


    Great thanks!
    H.
     

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