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  1. #1
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    Please help me for this issue...

    Hi all

    My 92" 735iL runs great, doesn't use any oil between oil change (7500 miles), gives me a fair 20mpg, its does not overheat... but recently it starts to miss between 2500 rpm and 3000 rpm or around 60 mph, it's buckling bad but intermittent..

    My mechanics change the fuel filter, check the fuel pump, rotor and rotor cap, spark plug wires everything is OK except that the spark plug of #6 cylinder is fouled black with oil. He check the compression and all six cylinders are good... and he said it's the #6 cylinder that make the car miss.

    so my question are:

    1. if compression is good on the #6, where the oil coming from?

    2. why there is no oil on the other 5 cylinders

    thanks a lot in advance for any idea,

    dan


  2. #2
    dan02
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    ooops...

    I forgot to mention that the car has 252 K. miles, head redone once at 125K.

  3. #3
    maun
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    Re: Please help me for this issue...

    I would check/clean the idle air control valve and spray throttle cleaning fluid into the throttle body.

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    thanks

    thanks..

    but how it would affect the cyl #6 and not other cyl?

  5. #5
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    Inner Circle ©156 since: Aug 14, 2003 cheung1 is an unknown quantity at this point cheung1's Avatar
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    Try an adapter to recess spark plug #6 to prevent

    oil foul. There are two sizes of adapter in the local auto store. Buy the longer one. Whether tapered edge or a flat edge with metal washer doesn't matter. The idea is to recess the spark plug tip into a hole in the adapter where oil can't reach. It doesn't fix the cause of oil leak into cylinder #6 but will keep the plug tip dry--I had had cyl#3 plug tip foul in less than two weeks and got dry tip after using the adapter.

    As for why oil in cyl#6, I have heard that the 735 head is prone to develop crack in #6 area, although I though in that case coolant would go into the cylinder, not oil.Patrick C 88 750 159K

  6. #6
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    Re: Try an adapter to recess spark plug #6 to prev

    thanks Patrick, I will try that. Yes it could be a crack in #6 because there a tiny bit of oil in the coolant, but I have no coolant loss (not yet). I searched a round and someone told me that it could be worn valve guide on the #6 cylinder.

    thanks again


  7. #7
    etachu
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    Re: ooops...

    I seem to think that the problem is more likely to be from worn valve guide seals on the #6 cyl.

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