Transmission Fluid Contamination

natsmart Apr 15, 2019 at 6:06 AM

  1. natsmart

    natsmart New Member

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    Looking for some information on possible ways that my transmission fluid could have got contaminated during a service.

    The services was a 90 month or 150000km. The car has only done 85000km. In addition to the service the timing belt was replaced along with idler pulleys, tensioner, water pump and they sent the radiator away to have the top tank replaced due to a hairline crack in the top outlet pipe. Neither the radiator or water pump were leaking.

    How could contamination of the transmission fluid have occurred?

    Images of contaminated transmission fluid attached.

    trans oil 2.jpg trans oil.jpg
     
  2. StarCruiser

    StarCruiser Well-Known Member Supporter Guru I am in uk

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    What exactly is the transmission fluid contaminated with?
     
  3. natsmart

    natsmart New Member

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    Not sure. The service center said it was water.
     
  4. uHu

    uHu Well-Known Member Supporter I am in sri_lanka

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    I suppose the 200 as well has the ATF going through the bottom of the main radiator. That would be the most likely place for water contamination. The 120 series in particular has had this problem, ruining a few auto boxes.
    Theories:
    It could be that the old radiator had a crack also at the bottom, or the new one has? Or maybe that the new radiator was pressure tested with water, which was not removed from the ATF portion before fitting?
    Or maybe the boys fitting the new radiator just spilled a lot of coolant when the ATF hoses were off?
     
  5. StarCruiser

    StarCruiser Well-Known Member Supporter Guru I am in uk

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    Either way it boils down to poor mechanical practice to not plug the transmission hoses while the rad was off. Are you certain the ATF was not contaminated before the rad was removed?

    Are you having problems with your auto box?
     
  6. natsmart

    natsmart New Member

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    They didn't replace the whole radiator, they just sent the radiator away to get the top tank replaced as this was the cheaper option. As far as I know there were no leaks in the original one prior to going in for the service.
     
  7. natsmart

    natsmart New Member

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    It could have been contaminated at any point during the service, I notices the running issues when I drove it home. The car started to shutter and lose power whilst accelerating. It also clunked into gear a couple of times. They flushed the transmission fluid a number of times and test drove it and said the car was running fine. When I drove the car the next day I could still feel a shutter, loss of acceleration, slow gear changes etc etc.

    The other option is that they didn't refill the transmission fluid after loosing fluid during the radiator repair and the transmission has overheated.
     
  8. natsmart

    natsmart New Member

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    How
    How would the ATF be contaminated before the rad is removed? Is there a possibility that the coolant can flow from the radiator to the transmission? We are looking at all possibilities at this point in time.
     
  9. StarCruiser

    StarCruiser Well-Known Member Supporter Guru I am in uk

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    In a rad with a leak between the engine coolant side and the transmission cooler side, yes there have been instances of this on other models. You specifically mentioned ‘during a service’ in the OP, hence the question to determine how you knew it was during the service. Turn this on it’s head and have the rad pressure tested while off the car to see if it leaks into the transmission cooler or vice versa.

    There have also been instances of an auto box losing prime and being very difficult to get functioning properly again. I believe a gent with a 105 flushed his transmission and managed to get it better after driving it around for some time.
    The other possibility is that the fluid has been changed at this point for a fluid that’s different and incompatible with what was in there.

    Another possible way for an auto box to be contaminated with water is through the breather if it has done deep wading without the breather pipes being correctly attached. This of course is a different scenario to being contaminated during a ‘service’.

    The other question is, has it been contaminated with coolant or water? If it ran fine before and doesn’t now, it would appear that the problem has crept in during the ‘service’.

    It’s not possible on older models to completely change the ATF via the drain plug as it doesn’t allow full draining of the entire transmission including the Torque converter. No idea if this continues into the 200 series.

    Probably worth finding out what fluid it should have in it. What it had in it and what was put back in it.

    To rectify you may need to drop the fluid and replace it several times with a 100 miles or so of driving in between.

    The other thing is fill level. Best thing is to check level when it’s hot, engine running after cycling through all gears manually.

    You mentioned overheating, does the fluid smell burned?
     
  10. fbnss

    fbnss Well-Known Member Supporter I am in england

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    :laughing-rollingre:
     
  11. TONYCY11

    TONYCY11 Well-Known Member I am in cyprus

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    I have heard water contamination of ATF in the 90/95 series 4 speed , but I have never heard the 120 d4d suffer water contamination in the ATF in the 5 speed Trans , in some markets the 120 had the 1KZ engine and Auto Trans of the 90/95 maybe that is why the 120 with 1KZ could have suffered the problem with water contamination in the ATF .
     
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