Hi Michael,
Have you noticed a pressure changed recently or over time? Oil pressure
is very sensitive to engine rpm at slow idle & up to 1,500 or so. It is
also sensitive to oil type & viscosity. I run 20W-50 conventional oil.
My pressure runs about 40 when very hot at 1,200 rpm idle. Don't know
what it might drop to at a slower idle. Never tried it. Runs about 55
psi up to about 3,000 rpm when very hot & increases slightly to about 60
at rpm above 3,000.
It's possible that leakage of the relief valve could reduce pressure at
low pump output, (low rpm), but it doesn't sound like you have a big
problem. You could try seating the valve plunger with a wood dowel &
hammer. I wouldn't risk getting lapping grit into things. My engine
originally had this seating problem & correcting it raised pressure from
20 to 40 at 1,200 rpm. Somewhere around the same as yours is now. It
had no effect at higher rpm.
My relief valve spring is shimmed .360", the maximum that will let the
valve still work. I felt that the old spring, which had already taken a
set, would be less likely to change over time than would a new spring
which would gradually lose tension as it took an initial set.
I replaced a slightly worn pump when I installed the DW pan. It only
raised pressure a couple of psi. I also replace the pump output line
with braided flex as you suggested.
I don't think you have much to worry about. Sounds more than adequate to
me. If you just want to experiment, new springs are cheap.
Regards,
Dave Russell
BN2
Awgertoo@aol.com wrote:
> When I start my car up my OP is about 65 psi on the gauge with revs
> above 2000 and about 40 psi at idle. However after the engine and oil
> come up to temperature the OP drops to about 55 psi at revs above
> 2500 and falls off to about 40 psi with revs of 1500 and only about
> 20 psi at idle.
>
> Do I have an incipient problem? Last year I pulled out the relief
> valve spring and shimmed it about 1/4" which increased OP about 5
> psi across the board but I wonder if it is time to replace the
> spring with a new one and/or lap in the valve. Or is my oil pump not
> being all it should be?
>
> The engine was rebuilt about 50K miles ago but consumes virtually no
> oil, does not smoke and runs strong. I run 10W/50 synthetic oil.
>
> Am I worrying unnecessarily?
>
> Best--Michael Oritt, 100 Le Mans
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