Date: Sat, 2 Jun 2007 20:56:28 -0700
Reply-To: David Kao <dtkao0205@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Kao <dtkao0205@YAHOO.COM>
Subject: What's Wrong With my Compression?
In-Reply-To: <20070602213453.1CF091165C3@hamburg.alientech.net>
Content-Type: text/plain; charset=iso-8859-1
I am caught by surprise from my recent rebuild of my 1.9 engine for my 83 westy.
It's not really a rebuild. I dropped the engine and replaced the liner with a set
of new Cofap liner. Lots of assembling but not rebuilding work. After 250 miles of
breaking in I got 3 cylinders at 150 PSI but cylinder #3 reads less than 100.
Re-adjusted the valves. There wasn't anything wrong. Re-adjusted them anyway
but same result. I am at a loss why this is happening.
I did nothing to the block by assuming it still has some good life remaining as
the westy has only reached 110k miles this year. I only checked and lapped all the
valves of the pair of rebuilt heads by a VW dealer 30k miles ago. All vlave guides
are tight (no wear I can feel especially intake valves). After lapping I checked
valve seating by pouring rubbing alcohol into the combustion area (valve seated
by their own weight. I made sure there was no leak for 3 minutes. I thought I got
a pair of perfect heads.
Why am I getting compression out of #3 at less than 100 PSI while other three are
all at 150? My westy does run better than before. This tells me the new liner does
make a difference now. But if #3 has a compression of only 90 it makes the #3 a
dragging cylinder. I have cheked it 3 times. I don't think there is anything wrong
in how I tested it. Engine sounds really like a new one. I did a very good job
in assembling the headers and the exhaust. All valves are fairly quiet. They sound
just right to me.
Is it possible I got a lemon Cofap? Kind of disappointed by the result. I am not
sure if I did anything wrong. I am willing to drop the engine again. Any suggestions
at this point will be appreciated.
When I installed the liner I did not check the ring gaps for all rings. I did not
align the gaps to a Y shaped orientation either. I read from the archive and someone
said he used to check the gaps but stopped doing it because he never found it
necessary. He did not align the gaps either because they will move anyway. Can this
be the problem I am getting now? The reason I did not do it because it is difficult
to compress the rings and put the pistons back into the cylinders. I was afraid that
I might break any rings. Is this proven to be a big mistake now?
David
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