Pressure Tester (was Surging and erratic boost

Bernie Benz b.benz at
Wed Jan 3 11:24:57 EST 2007


Your original Q related to a check valve that might prevent crankcase
pressurization and resulting dip stick ejection. The check valve you point
out will not do so.


From: Phil Rose <pjrose at>
Date: Wed, 3 Jan 2007 10:39:44 -0500
To: Bernie Benz <b.benz at>
Cc: 200q20V mailing list <200q20v at>
Subject: Re: Pressure Tester (was Surging and erratic boost

At 7:33 PM -0800 1/2/07, Bernie Benz wrote:
> From: Phil Rose <pjrose at>
> At 1:30 PM -0500 1/1/07, PeterBergin at wrote:
>> When I test my system with that method, my oil dip stick launches
>> like a torpedo at about ~15 lbs.
> Isn't there a check valve in the crankcase breather hose that is
> supposed to prevent that?
I don't think so, Phil. How would such a device work in this case? The flame
arrestor is the only possible restrictor in the breather before it dumps
into the intake immediately ahead of the throttle body.

Have a look at the breather hose diagram posted by SJM

and read his description:

"This 1991 200TQ 20V breather hose also has a Tee in the center of the hose,
which connects to the intake manifold via a flow regulating one way check
valve and a molded rubber hose. The check valve will close under positive
manifold "boost" pressure. "


Phil Rose.....Rochester, NY USA
'06 A3q 3.2 V6 (5K, silver)
'91 200q      (156K, Lago blue)
'91 200q   (70K, Tornado red)
'89 100 (Bamboo gold)

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