I think you make a good point here and I'd to extend it a bit. Isn't the
purpose of the leak down test to test compression lost at the point where
you need compression the most, i.e. near TDC? I wouldn't think the test
would be very useful when performing it with the piston low in the skirt.
Allen in Seattle
'50 3100
----- Original Message -----
From: "Hanlon, Bill" <Bill.Hanlon@COMPAQ.com>
To: "Rob J." <a70ragtop@hotmail.com>; "_Oletrucks"
<oletrucks@autox.team.net>
Sent: Wednesday, January 23, 2002 12:37 PM
Subject: RE: [oletrucks] leak-down compression test
> 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
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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