Re: Causes/effects of low oil pressure (was Dan's 'queer' engine)

[steveb@newkla.kla.com]

> My '81 5+5 exhibits low oil pressure when idling warm.  Don't ask me
> numbers, I'm not sure offhand, but LOW, right down near the bottom
> of the gauge. It moves up to the green zone when revs increase, or
> when idling cold.  It idles a little rough when warm, but usually
> smoother when cold (even though auxil. air valve is shot and there's
> no fast idle when cold).  Could the oil pressure have anything to do
> with this, or am I way off track?  It's done 240k km (150k m) blows
> no smoke, and the plugs are never dirty, just a light greyish brown
> powder.  What would be causing the low pressure?
> 
... I don't have numbers either, but when the engine is idling and warm
the oil pressure does decrease to a very low value.  If you look at what
Audi has done with the newer cars with their dynamic oil pressure check
they allow somewhere around 10 psi at idle and then about 30 psi is re-
quired when the engine is running above a certain RPM.  I do keep an eye 
on the idle pressure, but I don't worry about it too much.

HTH!
Steve Buchholz
s_buchho@kla.com
San Jose, CA (USA)