[s-cars] More Positive Crankcase Pressure 101

[Philip Mische]

Precisely why I hate compression tests.  The only way to really uncover the
source of engine internal problems is to do a proper leak-down test, just
like Wilbur and Orville did a century ago.  A listen at the breather (or
with really bad rings just watch), a crack of the throttle to check the
intakes, and a quick trip to the exhaust pipe (admitedly it's a tangled path
from the exhaust valve on a turbo car) will tell you a lot of what you need
to know.  Looking at the pieces once the motor is apart makes the forensics
more challenging if there's no other data.

My 2DM.

Phil
----- Original Message -----
From: <DGraber460 at aol.com>
To: <QSHIPQ at aol.com>; <gary.kaklikian at hp.com>; <s-car-list at audifans.com>
Sent: Tuesday, December 09, 2003 9:47 AM
Subject: Re: [s-cars] More Positive Crankcase Pressure 101


> I recently swapped a replacement WX into my 83 URQ because the crankcase
was pressurizing to the point of blowing out the dipstick, which fits rather
tight, and giving the engine bay a nice oil bath. I had checked all the
check valves, hoses, and systems (even replaced with other known functioning
units), to find everything in working order. Did a compression check and
found #2 cyl. at 30lbs. compression. Bingo, I thought this was a standard
ring problem. On dissassembly, #2 bore and its rings look just like the rest
of them. Valves, stems, seats, and seals all look to be identical and non
problematic as well.
> Me and 2 other pro mechanics are totally puzzled from the visual
inspection. No apparent "smoking gun" as to why. The replacement WX is
running fine with all the same CCV equipment. A machine shop inspection
might find a ptoblem with #2, but visually it sure doesn't look like a
severe enough problem to account for 30lb. compression.
> I'm interested in what you find in the end.
> FWIW- I am running 18-19 lbs. (gauge) boost.
>
> Dennis
> Denver
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