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Thread: bmw e66 745li huge oil leak ,

  1. #1
    Join Date
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    bmw e66 745li huge oil leak ,

    got a great condition e66 745li , nothing wrong with it or i thought nothing wrong , reversed out of drive , did about 200yrds red oil light came on. switched engine off and could see a trail of oil along the way i had driven , would anyone have any ideas what would cause this , or has anyone had similar problem

  2. #2
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    The big common three are left and right upper timing cover and valve cover gaskets and the alternator mounting plate gasket on the lower left of the engine, that one can really pump the oil out because there's oil pressure behind it. There is also the oil pressure switch and vacuum pump. You will need to lift it and inspect. You may need to steam clean the engine first to get a better look.

  3. #3
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    Quote Originally Posted by jclausen View Post
    The big common three are left and right upper timing cover and valve cover gaskets and the alternator mounting plate gasket on the lower left of the engine, that one can really pump the oil out because there's oil pressure behind it. There is also the oil pressure switch and vacuum pump. You will need to lift it and inspect. You may need to steam clean the engine first to get a better look.
    thanks for that , im pretty certain engine is fine as i stopped quick , friend is picking it up and taking it to his garage so with those three places to look my mind is a lot more at ease at thinking i may not need to get a new engine

  4. #4
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    most likely the seal at the alternator bracket - time consuming job to replace a $9 part. This is like the femoral artery - a seal failure can dump all of the oil out of your engine in just a minute or so if the leak is big. This can be repaired easily, it just takes some time.
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  5. #5
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    Definitely sounds like the alternator bracket gasket. It is sealing a pressurized oil port. Leaking timing covers and valve covers will not dump out oil, because they seep oil that's not under any pressure. The other gasket will pump out pressurized oil if it fails, and will empty the entire oil pan in a hurry.
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  6. #6
    Join Date
    Oct 2012
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    Upper Marlboro, MD
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    2004 BMW 745Li
    That is the most likely leak, Alternator Bracket Gasket. It took me 6hrs back in June this year on my '04 E66 with only 135k miles.

  7. #7
    Join Date
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    2007 BMW 750Li
    I have an '07 750 E66 which has developed the large oil leak problem (a very fast drip, oil practically running out at front left of engine). Is there a procedure anywhere online, or is it fairly straightforward and you just have to get in there and start removing things until you can get the alternator bracket? I found a procedure for an '02 745, would that be exactly the same, or mostly the same?

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