Date: Wed, 5 Sep 2012 22:25:30 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Made the mistake of checking compression
In-Reply-To: <017101cd8bc7$889a2a90$99ce7fb0$@gmail.com>
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You really can't say that with your current situation that you have any
"percentage" of design performance. The low cylinders can be a real problem
or no concern at all. The next step is to do a leak down test and try to
confirm that the valves, rings, are good or bad. Since it is both cylinders
1 and 3 (the two front ones) it is possible the low readings are due to a
worn camshaft (this is common) or the cam bearings are so worn it is
floating at the front of the case. In either case the problem is the reduced
valve lift. Worn bearings will often show up as low oil pressure.
If the low compression is due to ring or valve damage then you have to
consider the risks of further operation. Bad intake valves are very
confusing to the fuel injection as they are some combination of internal
vacuum leaks and combustion gasses. Extreme failure can result in a flame
front going into the intake tract burning up the intake boots and even
getting past the throttle body. Yes one of the jobs of the air filter
assembly is flame retention from back firs and other causes of flame coming
back from the air intake system.
Then there is the fact that with some cylinders down the others are working
harder. When you need the engine the most far from home may the melted
pistons, thrown rods, and other reasons to walk home begin.
At 140K the top end of the engine owes you little. If the bottom end is
healthy then a vlave job or set of heads may get you another 50K plus. You
need some good information though to make a good decision.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Stuart MacMillan
Sent: Wednesday, September 05, 2012 8:36 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Made the mistake of checking compression
The ole 1.9 with about 140k on it runs like a top but has 90-150-100-130,
(no increase with oil squirt). Using 150 as a benchmark I figure I'm running
about 78% of original HP of 82, or 64 HP, and about 91 ft/lbs of torque, as
opposed to 117.
And I thought it was just the AT that gave me poor acceleration. It's like
driving my '68 Westy again, and I don't want to go back there.
So, for you experts, how many miles do I have with these worn valves? Is it
worth new heads with this many miles for $1000 in parts? I'm not going to
rebuild this engine.
I may run out of patience with it before it dies or I do, I'd like to be
able to merge on an uphill freeway ramp without getting killed. I live in
hilly country, plus there are mountains I like to visit.
Opening a Vanagon engine conversion savings account tomorrow, and I'll need
at least a year.
Thanks!
P.S.: Wish I'd known about that one featured on Jalopnik!
Stuart
Tired '85 Westy in Seattle