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Possible vacumm leak

Posted: Sun Sep 09, 2007 10:32 am
by ytt105
1993 RR 3.9 V8. I think I have a permanent vacumm leak. You can hear what appears to be a leak on the passenger side, but as the petrol and LPG intake are on that side I'm not completely sure.
An old trick that worked for all BMWs was to pull the dipstick out while the engine was idling and if you DIDN'T have a leak the revs would change. If you DID have a leak then the revs wouldn't change as you already had too much air going in.
Is this the same with the V8.
Pulling the dipstick or removing a vacumm hose makes NO difference to my idle.
The only thing that I can think that could be leaking on that side of the engine is the dipstick tube. Is there a seal at the bottom of the tube where it goes into the block?
Any other suggestions.