[6pack] New Engine AUTOpsy

[Ruffner, James A *HS]

Oil pressure is set by a relief valve that is composed of a spring and ball
bearing that are inside of a drilling.  This is a separate device, much like
that in an OD unit, and is adjustable in some engines.  For these, there is a
bolt that presses on one end of the spring, with the ball bearing at the other
end of the spring.  As oil pressure rises in the main oil gallery the pressure
forces the ball away from the opening, which in turn allows the oil to escape
back into the sump.

Pressure is determined by the "k" value of the spring (k = spring constant.)
If the spring weakens over time (not uncommon in old engines), its k value
drops, and oil pressure also drops.  I've seen in the past TRF advertize these
springs as well as the complete unit.

It is possible for some, and perhaps all, of the oil ports to be clogged, but
you will still see normal oil pressure.  But this is pretty unlikely.

________________________________________
From: 6pack-bounces+jar7u=hscmail.mcc.virginia.edu at autox.team.net
[6pack-bounces+jar7u=hscmail.mcc.virginia.edu at autox.team.net] On Behalf Of
Robert Lang [lang at isis.mit.edu]
Sent: Tuesday, September 09, 2008 12:03 PM
To: Scott Tilton
Cc: 6pack List
Subject: Re: [6pack] New Engine AUTOpsy

On Mon, 8 Sep 2008, Scott Tilton wrote:

> Someone who knows more about the oiling paths than me might be able to
> comment on whether or not it is possible that there are blockages in the
> system that still allow for normal oil pressure readings even though little
> / no oil is getting out to where it needs to go.

The #1 main and consequently the #1 rod bearings are the furthest point
from the oil pump... rod #2 gets oil from the main #2, so there should be
no damage there _if the problem was the oil feed.

The rust on the top of the motor is something else, but it indicates to me
that there was water INSIDE the sump or a lot of condensation in the valve
cover area... was the motor stored in the upright position???

I agree with Vance - it'll cost more to fix the crank than to get another
servicable used or new (my pref. is NOS) crank. They are def. available
from various sources.

I'll also point out that if you run the motor starved for oil, the #1
bearing will spin first. The damage to the cam probably came later, but
verify that your oil filter is in play for this motor...

I'm thinking that there was some crud in the oil line that blocked oil
flow from the #1 main to the #1 rod.

Regards,
rml
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