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