Subject: RE: Guzzi machinists near Sacramento, San Francisco CA?
Author: Bruce Giller
Date: Mar 24, 2005, 5:00 AM
Post ID: 1718592799
And don't forget that when testing the sealing capacity of piston/rings
either by compression testing or leakdown, get the engine up to operating
temperature. If the it is cold, all the readings will be quite low and
utterly useless.
Bruce
-----Original Message-----
From: Patrick Hayes [mailto:peha-@comcast.net]
Sent: Wednesday, March 23, 2005 4:14 PM
To: Loopfram-@topica.com
Subject: Re: Guzzi machinists near Sacramento, San Francisco CA?
gerar-@netzero.net wrote:
| I pumped air into the Guzzi's spark plug hole at TDC compression with the valves within spec and I could feel air coming out of the oil drain plug hole. It was not even hissing which worried me. Incidentally a vintage BMW friend came by and we took compression tests as a hoot. 175 psi, both cylinders. I have to be suspect of the compression reading. |
Don't be so quick.
First, how did you LOCK the engine at TDC? Air will blow the piston
back down unless you have the flywheel locked in some way.
Second, were you certain to be on TDC of the compression stroke? There
is another TDC between the exhaust push and the intake suction. Can't
get valid readings there.
Third, how did you "pump air" into the cylinder? Just hold a nozzle up
there? Converted an old spark plug to an air jack? Built yourself a
leakdown tester?
Fourth, that compression seems fine. I wouldn't tear into a motor that
had that compression, especially if both sides were near each other.
What was the difference between the two sides? Did you hold the
throttle WFO during the test?
Fifth, I have a leakdown tester. You're welcome to come by and use it.
Will tell you a lot of info in about 10 minutes. Worth knowing before
you dismantle.
Patrick Hayes
Fremont CA