RE: Vacuum-leak question...please clarify

[Aleksander Mierzwa <alex@matrix.com.pl>]

I've heard the following explanation on this list, don't remeber who was
the author, though:
Vacuum leaks create lean condition. When you have no vacuum leaks
removing the disptick will cause the engine to run lean, but not enough
to make it stall. If you already have vacuum leaks, the additional leak
through the dipstick makes it run so lean it stalls. This makes sense to
me - my engine still runs when I remove the dipstick (smaller leak), but
stalls if I remove the oil cap (larger leak). Anyone can clarify this?

Aleksander Mierzwa
Warsaw, Poland
mailto:alex@matrix.com.pl
87 Audi 5000CS turbo (mine)
88 Renault Medallion wagon (mom's)
91 mountain bike (just in case both cars broke at the same time :-)

> -----Original Message-----
> From:	Alex Kowalski [SMTP:lawguest@wppost.depaul.edu]
> Sent:	Thursday, November 06, 1997 5:59 PM
> To:	quattro@coimbra.ans.net
> Subject:	Vacuum-leak question...please clarify
> 
> Please excuse my ignorance, could somebody please clarify this for me?
> 
> Alexander Mierzwa wrote:
> 
> > With the engine idling, remove the oil dipstick.  If the revs drop
> it's OK,
> but if the engine stalls or is about to stall you have a vacuum leak.
> 
> I was under the impression that opening the oil-fill cap or removing
> the
> dipstick should <cause> the engine to stall or come very close if
> there
> are <no> vacuum leaks, because opening either of these two orifices
> <causes> a vacuum leak which drops the throttle plate suddenly and
> makes the engine stall?  Isn't the crankcase being under vacuum what
> causes the rear-main-seal whistling?  
> 
> I am confused.
> 
> Best Wishes,
> Alex
> 
> 
> 
> 
> 
>