Date: Sun, 8 Aug 2004 15:51:54 -0400
Reply-To: "Daniel L. Katz" <katzd54@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "Daniel L. Katz" <katzd54@YAHOO.COM>
Subject: Re: Diagnosing a low (8-10 inches) vacuum gauge reading
john:
with gauge connected at port to vacuum advance, measure vacuum AT PART
THROTTLE, not idle.
cited compression results are such that it would be surprising not to pull
a healthy 20" vacuum with engine at part throttle.
vacuum at advance port is SUPPOSED to be low at both idle and full
throttle, and high at part throttle.
dan
On Sun, 8 Aug 2004 01:33:48 -0700, jbclem1 <jbclem1@CHARTER.NET> wrote:
>Hi Bob,
>
>When you say that low vacuum is very common, do you also mean that it's
normal...or just caused by
>something else?
>I am expecting to find something like the cylinder to cylinder head flat
gaskets bad, and I do burp
>the system occasionally with the pressure cap, but it pressurizes too
quickly to be able to do that
>regularly. I like the idea of the small valve on one of the cloth hoses,
I was thinking about an
>automatic pressure relief valve.
>
>About changing the intake valve adjustment to .006, do you do that with
self adjusting lifters(where
>the adjustment is usually set snug plus i think 1 3/4 turn). You're
backing off the adjustment to
>.006? Is this just for testing purposes, to see it's effect on the
vacuum reading, or do you run
>the car with that adjustment?
>
>Thanks for the suggestions,
>
>John
>
>
>
>----- Original Message -----
>From: "ROBERT DONALDS" <donalds1@VERIZON.NET>
>To: <vanagon@GERRY.VANAGON.COM>
>Sent: Saturday, August 07, 2004 6:40 AM
>Subject: Re: Diagnosing a low (8-10 inches) vacuum gauge reading
>
>
>this low vacuum is very common with the vanagon engines but I don't see
it tied into a combustion
>gas leak into the coolant. If the engine was overheated and the inner
gaskets received to much crush
>caused by the cast iron cylinder expansion then the that would be one
explanation. The other
>possibility is a cracked cylinder head. you stated that the engine is
only 10K old did the rebuilder
>use OEM heads they commonly crack and recrack when welded and are known
to have uneven head gasket
>surfaces. I had a 85 that would seal the inner head gaskets once the
engine would warm up and you
>could drive all day without problem but I did need to burp the system
after the engine got up to
>temp. This can be dangerous I used a small valve tied into one of the
cloth hoses to do this and
>dont recomend burping the coolant system with the pressure cap
>
>The compression could be 140 150 cold and 80 hot if you are reading the
vacuum hot and the
>compression cold then I would consider adjusting the intake valves
to .006ths cold and testing the
>vacuum again hot.
>
>Bob Donalds
>Boston Engine
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