Much easier to turn over the engine than un and the readjust the valves.
Besides that the differences in volume from piston up to piston down
would greatly change the percentage leak down rate. The rate would be
much lower with the piston down.
-----Original Message-----
From: Rob J. [mailto:a70ragtop@hotmail.com]
Sent: Wednesday, January 23, 2002 2:13 PM
To: _Oletrucks
Subject: Re: [oletrucks] leak-down compression test
Would it be possible to simply loosen the rocker arm assembly, removing
the
pressure on the valve springs? That would eliminate having to
individually
put all pistons at TDC in order to ensure the valves are closed. Seems
that
percentage drop should not matter whether the piston is at TDC, or
bottom or
middle. Just a thought.
Rob
My Zen Moment for the Day: Don't be irreplaceable. If you can't be
replaced, you can't be promoted.
----- Original Message -----
From: "A.B." <bigfred@unm.edu>
To: "Dana Muise" <dana@spazzco.com>
Cc: <oletrucks@autox.team.net>
Sent: Wednesday, January 23, 2002 12:04 PM
Subject: Re: [oletrucks] leak-down compression test
> On a leak down the PSI isnt' really all that important, you are really
> just looking for the percentage of leakage, ie, if you put in say 50
psi
> (w/piston at TDC so it doesn't turn the motor and the valves stay
shut),
> and lose 2.5 psi you are losing 5%, 100 psi is the easiest, I use that
on
> modern motor cycle engines, but I dont' know if that is a safe
pressure
> for these older motors. I assume it should be fine.
> -alfie
>
>
> On Wed, 23 Jan 2002, Dana Muise wrote:
>
> > Hey truckers
> > I did a compression check on my old 235 last week and all 6
cylinders
came in
> > about 10 lbs below the minimum. The manual said to put a little oil
into
the
> > cylinders and try it again. They all checked great after that.
People
are
> > telling me this indicated worn rings. Does any one have any theory
on
this?
> >
> > I'm going to perform a leak-down check this week-end. I'm told you
have
to
> > listen at the tail pipe or intake for hissing (bad valves) or oil
breather for
> > bad rings. Is this right? It doesn't seem very accurate. Does anyone
know what
> > the PSI range is for this check?
> > Thanks for you help!
> > oletrucks is devoted to Chevy and GM trucks built between 1941 and
1959
> oletrucks is devoted to Chevy and GM trucks built between 1941 and
1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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