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Thread: 2008 X5 3.0D 2nd engine failure in 2 months!

  1. #1

    Unhappy 2008 X5 3.0D 2nd engine failure in 2 months!

    Hi, Iím new here and am seeking some advice about my Dadís 2008 X5 3.0 diesel (single turbo). He has had the car about 3 years and has just experienced his second engine failure in 2 months! Car is fully maintained by a trustworthy local ex BMW master mechanic who installed an Autologic tune a year ago. First engine failure occurred when car was dropped off for a service (running fine?). Car had sat for little while and when the mechanic went to start it and it started making a tapping noise.
    Turns out an injector was stuffed and cylinder 6 had a bent rod and a twisted crank. There was some water in the fuel, but not heaps. The mechanic suggested the injector failed open (in a big way) and flooded the cylinder with fuel after the motor was turned off. When the car was re-started the cylinder was full of fuel (and possibly some water) and caused a hydrolock.
    All injectors were replaced along with the high pressure fuel pump. The motor was rebuilt with a new piston, rod, bearings and crank, and the head serviced. Huge $!

    The car ran well for 6 or so weeks and then there were two sudden bangs whilst driving slowly and the car went into limp mode. There was heaps of error codes mostly related to cylinder 1. It turns out that cylinder 1 is now sitting about 0.5mm below TDC, so either has a bent rod or damaged gudgeon pin or bearing.

    We donít know yet if the new injector has also failed. Irrespective, I donít see how enough fuel could possibly get in the combustion chamber to hydrolock whilst the motor is running. This leaves me thinking either too much boost or very wrong timing. I suspect either the ECU or the tune is at fault.

    Car has run well after tune install and then in between failures. My dad mentioned some turbo whine at slow speeds, though I donít know if that is normal or not.

    I assume that the ECU wonít allow too high boost, unless the tune overrides that. Being a diesel, the combustion is compression related, but I wonder if the fuel charge is somehow occasionally firing too early. Though, there must be knock sensors.
    I wonder if either the tune or ECU is experiencing an intermittent major melt down.

    Does anyone have any other theories or suggestions?

    There is also the question of what to do with the engine now. The mechanic suggested that it may not be necessary to replace the con rod if the piston is only 20 thou" (0.5mm) below TDC. From what I have read 10 thouĒ is max allowable difference.
    The tune is definitely coming out. I wanted to buy a replacement second-hand ECU, but the mechanic tells me that only a new ECU can be coded with the car.
    We are so worried about rebuilding the motor, only to have it blow up again!

    Thanks for your help.

  2. #2
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    Jim, I can only think the head was leaking at the first overhaul, and it may have been overlooked! It may be a warped head and may have to skimmed.
    I can't comment on the "Autologic" Tune or the need for it initially.
    RegardZ

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    I would suspect that if the engine wasn't rebuilt correctly, you would have noticed straight after, not after 6 weeks.

    To be honest, it might be worth taking it to BMW and get a second opinion...

  4. #4

    Default 2008 X5 3.0D 2nd engine failure in 2 months!

    Quote Originally Posted by jnrdavo View Post
    I would suspect that if the engine wasn't rebuilt correctly, you would have noticed straight after, not after 6 weeks.

    To be honest, it might be worth taking it to BMW and get a second opinion...
    The head was checked both times by a head specialist.

    As it turns out Autologic who supplied the tune also does diagnostic equipment as well, so they are going to attempt to interpret the error codes to see if they can work out what is going wrong.

    I will be pushing for the bent rod to be replaced. As it turns out the BMW dealer is only 1km away from this mechanic, so I think that it's first stop after getting the motor running should be a 2nd opinion.

    Thanks

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