Date: Sat, 19 Mar 2005 15:41:54 -0700
Reply-To: Larry Chase <roadguy@ROADHAUS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Larry Chase <roadguy@ROADHAUS.COM>
Subject: Re: Another compression question
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Barry,
I'd agree with John on this one.
I think your results .. "if tested cold" are simply normal for a healthy
engine that is getting tired.
I would not be afraid of getting another season out of her.
As an example,
When Ben & I put the New AVP rebuid in the Haus last June, the compression
tests yielded the following,
at 300, 500 and 1,000 miles.
Tested cold:
135 125 130 138
Larry Chase
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Date: Fri, 18 Mar 2005 13:53:30 -0700
From: Anonymous Digest <jbrush@AROS.NET>
Subject: Re: Another compression question
>As I recall, most cylinders registered around 110 to 118 or 119 PSI.
>One was in the 122 to 125 range.
>The engine has 206k Km on the odometer. Is this a sign from the VW gods
>that that engine is not in the best of health?
>Can I trust this motor ? Will it get me thorough another season ?
Well, first of all, no one has answered the issue of whether the published
specs are for a warm engine or a cold one. I think a good point was made in
that dry or oiled in the cylinders will have an effect as well.
Which way was the testing done? I bet if it was done cold, doing it on a
hot/warm motor would increase those numbers a bit.
Bentley says that the water cooled engine is nominal 145-189psi, minimum is
116psi, and the max difference between any two cylinders should not exceed
44psi. Your numbers are quite low based on that info, but since the
cylinders are all fairly close to each other in psi, I think you have an old
engine that is just wearing out. If you had one that was way off from the
others, then that would be a concern.
Overall, they read low, and in an ideal world, it would be nice to get a new
motor, and the extra HP the higher compression would bring, but one person's
opinion is that there is nothing wrong to be worried about based on those
numbers, other than a motor wearing down equally in each cylinder, which
means less power than a newer engine.
My air cooled is on the low end of the spec as well, but they are all nearly
equal in psi, and it shows in the power department, but it runs smooth,
doesn't burn oil, and short of dropping the feared valve seat, I think I
have a lot of miles left in it.
Take the trips, enjoy the ride, and post the pictures where we can see them
:-)
John