Date: Tue, 17 Mar 2009 11:59:51 -0700
Reply-To: neil N <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: neil N <musomuso@GMAIL.COM>
Subject: Re: Low compression results accurate?
In-Reply-To: <COL0-DAV3423E807FE4B02C5D4BC3FDB980@phx.gbl>
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On Tue, Mar 17, 2009 at 12:38 PM, Edward Duntz <eduntz@hotmail.com> wrote:
> I went to look at a partially-disassembled Vanagon yesterday to use for its
> engine in my tired '85. The parts van ('90 with auto trans and 2.1)) had a
> lot removed, including the computer, distributor, and battery. I wanted to
> do a compression test on it- the starter and transmission were still
> connected. I hooked up jumper cables- positive on my battery to the big
> terminal on the parts van starter; negative on my battery to the
> transmission on the parts van; and a jumper wire from the big starter
> terminal to the spade terminal on the solenoid. Each time I wanted to crank
> the engine, I held the terminal onto my positive battery terminal.
>
> I got readings of between 80 and 90 psi on each cylinder. The results I got
> seemed too low to be accurate, so I was wondering if there was something
> else in the situation that could cause results so low. Obviously the engine
> had not been at operating temp before the test was done, but I couldn't
> control that. The starter did crank slowly, but I let it turn over enough
> until the gauge didn't rise any more.
>
> The owner said the engine had run fine and had power on the highway. I
> suppose that you can get up to highway speeds even with low compression,
> albeit very slowly. But would it even start and run with compression so low?
>
> I wanted this engine to put in my '85. I could take the whole van 9what's
> left of it) for a decent price and maybe part out the rest of it, but I
> really wanted it for the engine.
>
> Thanks for any advice,
> Ed in CT
>
Good news is that each cylinder has similar readings.
If you haven't tried this, remove all the spark plugs, make sure
there's enough oil in the crankcase, and spin the motor for a while.
It may be that the rings aren't sealing as well as they would under
normal circumstances.
Splashing some oil around inside might make a difference.
Neil.
--
Neil Nicholson '81 VanaJetta 2.0 "Jaco"
http://tubaneil.googlepages.com/
http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines
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