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Discussion Starter · #1 ·
Hello folks. I need expert help, please.
I have 325i 2002 vintage, manual. It sprung a leak recently kind of weird: oil get pushed from the oil pan through the o-ring of the dipstick tube. First I thought I damaged that o-ring last year when I was replacing CCV. So I went and replaced that o-ring again. To my amazement, after about 3 minutes of idling at various rpm I saw oil bubbling there again. OK, I disconnected CCV return oil line from the dipstick tube, took clean clear tubing, stuck it into the drain pipe an blew air with my mouth, be careful with assumptions: I have clean clear plastic line between my mouth and drain line. Basically, I checked if there are any obstructions in the line. No everything went fine air blows inside with very little effort. I started engine and, without connecting drain line, of course no pressure inside oil pan, so no oil leak, from drain line after a few minutes starts coming some steam, like if you have oil cap off. Seems normal.
My next step in troubleshooting was disconnect line from valve cover to CCV. OK, start engine, wait, no oil leak. OK it does make sense.
My last step in troubleshooting was disconnect lines from the rail above intake manifold to CCV and check them for obstruction. The interesting that I was able to duplicate oil leak just with pressure from my lungs, just by blowing air into the one port of CCV valve, while plugging other port with my thumb.
Well, that how I deduced, that all lines and CCV are clear of any obstacles.
Then good question; why excess pressure form inside the engine didn't get into intake manifold? Does it mean that engine has insufficient vacuum on intake? But than OBDII should through warning light, right?
Any way, I am puzzled and asking for piece of collective wisdom. Does any one has a suggestion?
Sincerely,
Mark
 

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The oil dipstick O-ring should not leak if in good condition. Eventhough you replaced it; I would get a new O-ring (make absolutely sure is the correct part no. for your car and get it from the dealer -to make sure is within tolerance. There is a lot of variations during seal manufacturing/curing -don't ask me how I know), 2nd, I would make sure the o-ring was installed correctly -meanining it sits properly and has not twists.
 

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Discussion Starter · #3 ·
Thanks, daguzz,
I, of course, could potentially mess up a $2.0 o-ring from dealers stock room, though my ego will never let me to admit.:shhh:
I had that thought in the back of my mind that my lungs shouldn't be powerful enough to break seal of o-ring:facepalm:
But even any positive pressure should be sucked up into intake manifold, am I wrong?
Thanks,
Mark.
 

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Sorry to revive an old thread but will a bad dipstick "o" ring (able to twist and pull out easily) able to cause a minor vacuum leak in the oil system? I'm wondering the same thing and the question was never fully answered.
 
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