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ECU flooded with engine oil

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by Tizz2930, Feb 17, 2019.

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  1. Tizz2930

    Tizz2930 New Member

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    HI All
    I'm new to the forum and hoping I could get some advice.
    I have a 2005 C180
    Recently the engine diagnostic light came on and the garage I took it to have told me there is an engine oil leak which has pushed oil through the loom and flooded the ECU. They have said it is a common fault on this car and not worth fixing as it would cost more than the car is worth.
    As the car mechanically and body is still good I wanted to get a 2nd opinion on this and find out if the issue can be resolved with 2nd hand parts etc for less than the £3000 the garage have said it will cost.
    I would really appreciate any guidance from members
     
  2. John Laidlaw

    John Laidlaw Senior Member

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    Did they say where the oil leak is from?
     
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  3. OP
    Tizz2930

    Tizz2930 New Member

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    Hi John thanks for responding they said the cam sensors failed which means the oil pushed through the loom, not sure if that helps? I'm planning to call them tomorrow to get some more details. I did have an oil leak fixed about 18 months ago so would like to be clear if the damage is as a result of that or if this is a new leak which is still leaking.
     
  4. star

    star Forum Supporter Authorised Forum Supporter

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    It will be the cam actuators, known fault. You’ll need to fit blocker looms however there will be oil in the wiring loom that will ruin the lower o2 sensor. The engine Ecu can be opened and the oil cleaned out but the loom will need replacing.
     
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  5. OP
    Tizz2930

    Tizz2930 New Member

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    Thanks for your response, what kind of money are we talking about to replace the loom?
     
  6. OP
    Tizz2930

    Tizz2930 New Member

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    Hi John thanks for responding they said the cam sensors failed which means the oil pushed through the loom, not sure if that helps? I'm planning to call them tomorrow to get some more details. I did have an oil leak fixed about 18 months ago so would like to be clear if the damage is as a result of that or if this is a new leak which is still leaking.
     
  7. star

    star Forum Supporter Authorised Forum Supporter

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    A couple of hours work plus loom.
     
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  8. LostKiwi

    LostKiwi Senior Member

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    Yes this is a common fault with that engine.
    You should be able to repair it for a lot less than the £3000 quoted. All you need is (this is probable not definite) a pair of cam magnets, two oil blockers (to stop it happening again), a lot of brake cleaner and most probably an O2 sensor. You'll also need a big chunk of time.
    You'll need to dismantle a fair bit (ECU for a start) to chase the oil out using brake clean. Hopefully the ECU will be ok once the oil has gone. The loom you can try soaking in brake clean to chase the oil out, it will take a while but you may end up changing it. The O2 sensor is likely the cause of the light being the lowest point. Several on here have had the same issue and resolved it this way.
     
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  9. OP
    Tizz2930

    Tizz2930 New Member

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    Thank you
     
  10. OP
    Tizz2930

    Tizz2930 New Member

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    Thank you for responding.It's reassuring to know I can potentially get it repaired for less. I don't use a car much at the moment so didn't really want pay out to buy another one. I'm not mechanically minded so will need to find someone to do it for me,I get the impression the garage I took it to originally are not keen on the job which may be why they have advised me its not worth repairing. Would you recommend I find a Mercedes specialist or is it a job any garage can tackle?
     
  11. LostKiwi

    LostKiwi Senior Member

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    Whereabouts are you located? We may be able to recommend someone.
    The big cost here will be labour.
     
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  12. star

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    I would change the engine loom unless you are doing it yourself and you are still willing to risk contaminating the new o2 sensor if all the oil is not removed from old loom.
     
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  13. Frontstep

    Frontstep Senior Member

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    Lots of cars have oil in loom issues once you have stopped the leak I can't see why it couldn't be cleaned out of the loom if necessary by splitting it and recovering in places.
     
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  14. Oldspanners

    Oldspanners Senior Member

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    I had the same problem but not to the extent of yours.
    I would wait and see just how much oil there is in the ECU and make plans from there. I've seen one where a hole is carefully drilled in the casing and allowed the oil to drain out, I'd go easy on the contact cleaner as you could end up damaging it more than the oil would. The plugs for the ECU are easy to remove from the top of the unit just pull out the levers front and then rear to release them after removing on small torx screw holding the wiring.
    Check the O2 sensor at the bottom of the engine beside the LHS of the bell housing, this is the lowest point and where you will discover just how bad your problem is. The O2 sensor is just to the right of that on the exhaust you can get a Bosch replacement for about £40. Changing the cam magnets and fitting the wiring blockers is a easy job in an hour and about £150 for genuine parts.
    It all depends on how much oil has got in whether you need to replace the engine bay wiring harness and that depends on how many miles are on the engine.
    Either way it should be easily worth saving.
     
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  15. OP
    Tizz2930

    Tizz2930 New Member

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    I'm in Surrey near to Croydon, if you have any recommendations I'd really appreciate it
     
  16. OP
    Tizz2930

    Tizz2930 New Member

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    Thank you for your response I'm feeling relieved now it seems its possible to save it. Need to find someone to do the work for me though.
     
  17. star

    star Forum Supporter Authorised Forum Supporter

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    It can take a while to “drain” the oil from loom. If it’s gone from actuators to o2 sensor to engine ecu, it’s badly contaminated.
     
  18. LostKiwi

    LostKiwi Senior Member

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    Alex at AMF in Dartford, Cole at MBS Southampton, Wayne Gates in Harrow are all highly recommended.
     
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  19. John77

    John77 Senior Member

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    Where on a 2005 Eclass is the ECU and how is it opened to clean it? Also what do you clean it out with if needed?
     
  20. Oldspanners

    Oldspanners Senior Member

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    For the 200K it should be beside the air filter with two plugs on the top that are removed by pulling sideways the plastic levers. There is also a torx screw holding the wiring harness.
    It depends how much oil there is in it, some have carefully drilled a small hole in the casing otherwise try inverting it and clean the contacts with electrical contact cleaner whilst upside down but I wouldn't want much getting inside it.
    Here's a video of someone changing a MAF sensor but at 2:18 he shows removing the plugs from the ECU.
    Good luck.
     

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