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Thread: Oil leaks!

  1. #1
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    Oil leaks!

    I have found oil leaking from the back of the throttle body where it mates to the intake plenum.
    First question:
    Is this unusual?
    Second question:
    Suggestions for what causes that much oil to be sent into the throttle body?
    There is enough that it has run down the block and formed enough of a puddle on the skid plate to saturate a full sized shop towel.
    This all occurred as the idle went haywire and the engine misses during driving.
    For a complete list of symptoms review the thread heading: Motronic Throttle Position Sensor.

  2. #2
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    http://i1376.photobucket.com/albums/...ps9aauiu3f.jpg
    http://i1376.photobucket.com/albums/...psmcxxwl92.jpg
    This is what I'm seeing.
    There's actually enough that it has blown back under the car, almost to the fuel filter.

  3. #3
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    EXOTICS
    That seems to point to a problem with your Crankcase Ventilation/Oil Separator system.

  4. #4
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    crankcase ventilation is shown here http://www.realoem.com/bmw/enUS/part...BMW-735i&mg=11
    Shogun tricks and tips for the E32 series are HERE!

  5. #5
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    Quote Originally Posted by MIKYZZ4 View Post
    That seems to point to a problem with your Crankcase Ventilation/Oil Separator system.
    Quote Originally Posted by shogun View Post
    crankcase ventilation is shown here http://www.realoem.com/bmw/enUS/part...BMW-735i&mg=11
    I think you are right. This piece is cracked badly on mine.
    I already ordered the tube, and checked all other pieces.
    The vacuum line that leads from the tube , and is mmm marvelously hidden on the inside bottom of the plenum is free from obstructions, and thankfully seems intact.( I don't want to try to refit that tiny line onto the nipple under there).
    Should this have a ball valve in it at any place, like a PCV valve on other cars, or is it clear all the way through?

  6. #6
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    I am forming a loose hypothesis based on the findings above.
    The cracked crankcase vent tube is the vacuum leak that is causing the idle and misfire issues. As a result of the misfire codes being thrown, the car is trying to richen the mixture and possibly dragging more oil from the crankcase, into the plenum.
    Possibly?
    Another side effect is , the oil being dragged into the combustion chamber is not burning , causing further misfire, and beginning to foul the plugs, leading to even worse ignition.
    Last edited by Tarponhuntr; 04-07-2019 at 09:51 PM.

  7. #7
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    Yes, sounds plausible and is possible. Next step I suggest, you make a smoke test
    What is a Smoke Leak Test? copied: Leaks can present troubles for vehicle owners, but not all leaks are fluid leaks. Some leaks can be gas or air leaks. Unmeasured air flow through your engine throws off the fuel to air ratio. This can lead to poor engine performance. For example, one sign of this type of leak is engine hesitation, which is when the car has poor acceleration and reduced engine power. To prevent further damages, it is important to run a smoke leak test on your engine.A smoke leak test is a series of tests that will provide information on possible leaks present under the hood of your car in the vacuum systems. The vacuum systems will be tested using a smoke leak test. This test can determine if any piping in the vacuum system in your engine has a leak. A vacuum system controls the airflow in and out of the engine of your car. A leak can compromise this system because it will tell the computer of the car to emit more fuel, when more fuel isn’t needed. It throws off the air/fuel ratio of the car. A smoke leak test utilizes artificial smoke injected and measured by a specially designed smoke machine. The cost of these devises are high for the average person. Unless you are a devout grease monkey in your spare time, the best place to find a smoke machine is in the garage of your mechanic. The smoke is infused into the system with minor pressure. If any smoke visibly escapes, then it is likely there is a leak in your vacuum system. Typically gray smoke is used, but another color maybe used to make the leaks more visible. Often the mechanic chooses the color. It is important to run a smoke leak test on your car to ensure that it is safe to drive with no dangerous gas leaks. The smoke machine is a valuable tool for mechanics because it helps identify issues and will help prevent any other serious damages happening through neglect. It is common for the Check Engine light to illuminate when the car is started and to remain on, indicating that a problem exists. It is also easy to tell there are issues when you have trouble accelerating in the car. Depending on the severity of the leak, you may hear a hissing noise as an indicator that something is wrong.
    how to with cheap stuff https://www.youtube.com/watch?v=AsgB9eBl58I
    Vacuum lines http://www.nmia.com/~dgnrg/hose_map.jpg
    under intake https://www.bimmerforums.com/forum/s...ghlight=intake
    Shogun tricks and tips for the E32 series are HERE!

  8. #8
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    Outstanding Shogun! Hopefully, this time, I'm on the right track. Pulled the intake assembly off, all the way back to the plenum today. Cleaned the throttle body, and checked all the intake tubes over for cracks. The only cracks I've found thus far have been in the crankcase vent tube, but I did discover several other issues, including a cooked, exposed ground wire, and got that fixed.
    Maybe tomorrow I can get a smoke test done.

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