Date: Thu, 13 Sep 2007 14:27:17 -0700
Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Subject: Re: How do you check compression?
In-Reply-To: <914016.93147.qm@web82707.mail.mud.yahoo.com>
Content-Type: text/plain; charset="US-ASCII"
Here's what I watch for .
First, you'd like to see the needle on the compression gauge take a really
big jump on the first stroke, like if the final reading is going to be say
120, you'd like to see it shoot up to at least 80 or so on the first pump.
And NOT .....first 30, then up to 40, etc.......and finally getting all the
way up to 120.
I crank it about 12 pumps, or until the needle mostly has stopped raising.
Then of course for low reading you do a wet compression test on that
cylinder.
Scott
www.turbovans.com
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
David Kao
Sent: Thursday, September 13, 2007 10:43 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: How do you check compression?
It sounds like chuck, chuck, chuck. The needle of the gauge
will jump (upward) upon each chuck (stroke). The question
is should it be measured until the needle stops moving higher
or should the reading be taken at the 4th stroke.
Dennis suggested to take the reading at the 4th or 5th. But he also
said to read it until it reaches the highest reading.
I believe a cylinder with excellent compression will give you highest
reading on the 4th stroke. A cylinder not in optimal compression
will require 6 - 8 strokes to reach max. reading. So the reading as
well as number of stroke should both be considered for judging the
compression of a cylinder.
Vanagon engine seems need more than 4-5 strokes to reach max compression
reading. Correct me if I am wrong about this.
David
--- Michael Elliott <camping.elliott@GMAIL.COM> wrote:
> Engine warmed-up, cold, doesn't matter?
>
> Counting number of strokes -- is that the number of wuh-wuh-wuh sounds the
> starter makes?
>
> --
> Mike "Rocket J Squirrel" Elliott
> 71 Type 2: the Wonderbus
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
> KG6RCR
>
>
>
> On 9/12/2007 8:29 PM Dennis Haynes wrote:
>
> > Some more variables. Crank until gauge stops rising. You can hear the
> > change. Count the number of strokes. Should be 4-5. The design of the
> > gauge can affect this. The hose length and placement of the valve will
> > make a difference. Of course you will also want to do a leak down test.
On
> > older engines it is common for the front two cylinders (1-3), to show
> > lower compression then the rear and still check good with the leak down.
> > This can indicate worn cam lobes.
> >
> > Dennis
> >
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of
> > David Kao
> > Sent: Wednesday, September 12, 2007 10:31 PM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: How do you check compression?
> >
> > I was told by a mechanic that when checking compression for a 4 cylinder
> > engine I should get 4 strokes, no more than that, and get the reading.
> > But Bentley Manual says to continue to crank until getting the highest
> > reading. So how do you folks do it? How many strokes on the average do
> > you crank to get the highest reading?
> >
> > David
> >
> >
> >
> >
> >
> >
__________________________________________________________________________
> > __________
> > Luggage? GPS? Comic books?
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> >
>
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