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Thread: Oil leaking from filler cap

  1. #1
    Join Date
    Jul 2012
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    Orlando, FL, USA
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    1993 BMW 325i

    Oil leaking from filler cap

    Anyone have experience with oil escaping from filler cap? This is a stock m50 with a catch can setup, but lives at 5-7k rpm during sessions. I've tried a few brands of filler caps with no success.

  2. #2
    Join Date
    Jan 2010
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    Marietta, GA
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    95 M3, 87 535is

  3. #3
    Join Date
    Mar 2006
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    New York, NY
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    Z4 M, X3 35i, 550i
    On my n52 I had oil leaking but turned out to be the rubber gasket that got warped. I bought a new one and sandwiched both gaskets, no leaks since.

  4. #4
    Join Date
    Jul 2012
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    Orlando, FL, USA
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    1993 BMW 325i
    Valve cover is in good shape. I had that same thought yesterday about doubling the cap gasket and it was really tight getting it on, so I'm hopeful it'll work. I guess I just don't understand why there's that much pressure when the valve cover is ran to a catch can, and the catch can vents to atmosphere. I'll update the post after the nasa champs on whether doubling the gasket worked

  5. #5
    Join Date
    Jul 2012
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    Orlando, FL, USA
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    1993 BMW 325i
    The double gasket does not seem to work in my case. These pictures are from just idling and a few revs (was testing timing from a vanos install). The camshaft cover is installed. Is the powder coat causing a bad seal? Am I missing something obvious? Really trying to resolve asap before this weekend.

    20171018_162058.jpg20171018_162223.jpg

  6. #6
    Join Date
    Nov 2005
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    MA
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    Cayman S, Golf GSW, E30
    Seems odd to me. Some kind of pressure/PCV/CCV issue?

    This is an interesting thread:
    http://www.bimmerfest.com/forums/sho....php?p=5068323

  7. #7
    Join Date
    Jul 2012
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    Orlando, FL, USA
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    1993 BMW 325i
    Just wanted to close out on this thread. Oil still leaks, and seems to leak worse when the cap is not fully clean. Solution during the weekend was paper towels and zip ties. Below shows how much oil was being collected each session. Better than all over the bottom of my car, which is what had been occurring. Nothing caught on fire.

    20171020_110855.jpg20171022_104513.jpg

  8. #8
    Join Date
    Aug 2008
    Location
    St. Louis, MO.
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    1,018
    My Cars
    e36 332i
    Was the surface that the oil cap gasket seals to sanded at some point in prep for paint? It may be uneven from that and not sealing properly. Or the paint has mad the surface uneven.

  9. #9
    Join Date
    Oct 2013
    Location
    TN
    Posts
    88
    My Cars
    E36 & E46 M3 coupes
    I’m having this exact issue.

    I ordered what I thought was that oil cap gasket only to find that no one actually sells that. You have to buy a whole oil cap and the gasket is already inside it. What I ordered was this round rubber O-ring grommet thing? It goes over the oil cap well but underneath the coil pack cover. I’ve never seen this thing and I guess my car’s never had it since I’ve had the car. Instead of sending it back I figure I’d keep it and see if it remedies the whole ‘water in the plugwells’ thing I get from time to time...

    To fix the oil leak though, I just ordered a new oil cap. Hopefully that does the trick.

  10. #10
    Join Date
    Oct 2013
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    TN
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    My Cars
    E36 & E46 M3 coupes
    After further investigation, the oil cap was not the problem... Even though I replaced it anyway since the gasket on the old one was DEFINITELY fried.

    In my case I think it’s a simple case of the valve cover not seated properly on the new gasket towards the front of the engine. Maybe I tightened the rear part of it too much so that the front is just seeping oil... No leaks coming from the actual block or head, and not from that oil filter canister as I read on another thread. Going to be fixing this either today or tomorrow depending on if it rains here or not.
    95 M3 Coupe
    01 M3 Coupe

  11. #11
    Join Date
    Oct 2013
    Location
    TN
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    My Cars
    E36 & E46 M3 coupes
    After pulling off the cover and reinstalling it AGAIN, it's STILL leaking.

    After scratching my head and checking part numbers and breaking valve cover studs I looked at an actual write-up. According to the Turner one I just read, we're supposed to use RTV sealant on certain locations on the head before placing the new gasket on it. THIS has to be my problem... Will be doing this once my new stud and set of rubber grommets arrives.
    95 M3 Coupe
    01 M3 Coupe

  12. #12
    Join Date
    Jan 2010
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    Marietta, GA
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    95 M3, 87 535is
    RTV on the halfmoons in the rear and split lines in the front.

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