Date: Tue, 25 May 1999 14:34:59 -0400
Reply-To: Bulley <gmbulley@BULLEY-HEWLETT.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bulley <gmbulley@BULLEY-HEWLETT.COM>
Subject: Re: 82 compression test
Martin,
Do you mean that the *motor was running* when you did the compression
test?!? If so, your results could be very wrong. You don't usually check
the compression with the motor running, too many variables affect the
compression when the motor is in operation.
Here's a brief synopsis of how to perform a compression test:
Start with a fully charged battery, and keep the charger attached and
running (10+ amps)
Ground the coil wire. Disconnect the connection to each fuel injector.
Loosen all the spark plugs a few turns.
Crank the motor over for five or six seconds. (This blows away any dust or
dirt that may be around a base of the spark plug, so that it doesn't get
sucked into the motor).
Remove all spark plugs.
Place the compression meter at whatever cylinder strikes your fancy.
Climb in the driver's seat, step on the clutch, place the throttle all the
way to the floor, (this allows the motor to spin freely and take a full
gulp of air for each stroke, (important for this test).
Crank the motor over eight or ten times.
Record the reading; Repeat for each cylinder.
There are variations on this theme (wet, dry, hot, cold, record the first
stroke v. final pressure, etc.) but all of them are done following the
above procedure.
G. Matthew Bulley
Bulley-Hewlett & Associates
www.bulley-hewlett.com
Cary, NC USA
888.468.4880 tollfree
-----Original Message-----
From: Martin Laycock [SMTP:m.laycock@STRATH.AC.UK]
Sent: Tuesday, May 25, 1999 10:24 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: 82 compression test
Thanks for the that....It was hot and running with each spark removed for
the compression meter.
Thanks again
Martin Laycock
At 10:10 am -0400 25/5/99, KENWILFY@aol.com wrote:
>Martin, Bentley says for an aircooled Vanagon the compression should be
>between 87-131psi. 73 psi is minimum and no more than a 44 psi difference
>between the cylinders. Your compression test sounded kinda low to me too
but
>I am used to watercooled stuff and them aircooleds just aint as tight. So
>your compression tests look within limits. It also matters if the engine
is
>warm or if you are doing a cold compression test.
>Hope this helps.
>Ken Wilford
>Van-Again
>John 3:16
