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Dear All,

What would cause a constant oil pressure reading of 55 psi on a 1938 282 motor? The oil is 15W-30 Shell Rotella. In other words, the oil pressure readings for various situations:

Initial startup, engine cold: 55 psi
Idle, engine warm: 55 psi
30 mph, engine warm: 55 psi
60 mph, engine warm: 55 psi

It is also way to high an oil pressure, which might explain the oil leak at the top of the oil filter.

The shop manual says the pump pressure relief spring is "not manual adjustable" (37-38 Shop Manual, pg 49). If it is not manual adjustable, how do you compensate for really high oil pressure?

Thanks for your help.

Tom

Are you relying in the stock dash gauge? If so I would try a separate gauge just to verify. My 38 282 runs at a steady 30 psi.

Also check as perhaps someone "shimmed" the relief spring in the past.

Tom,

The service manuals say the pump relief valve spring is not adjustable, but I shimed the one in the Forty-seven Clipper for more oil pressure. I have a sneaking suspicion that I was not the first one to do so.

I would expect something like 35 lbs pressure with a warmed up engine at road speed (50 mph), more with a cold engine at start up, and less with a warmed up engine at idle (15-20 lbs).

The relief valve spring is easy enough to check as the pump body is on the outside of the engine on the RH side (but you know this). Just remove the large hex shaped cap and the spring and valve will be accessible, if they don't fall out on their own. A little oil will run out but no enough to be concerned about.

The leaking oil filter top is probably not due to the oil pressure, but rather a bad gasket seal. Good luck and let us know what you find.

(o[]o)

Thanks all for the help. The oil pressure was checked with a separate gauge, giving identical results.

I will check for shims. Given other modifications to the engine, this seems likely. I will report back soon.

Thanks!

Tom

Tom, have you had a chance to look further into the constant oil pressure reading?

(o[]o)

Quote:

Wow. Those numbers seem way too low to me. I think you really want around 42-45psi. What does the manual say it should be?

As for the leak around the top of the oil filter, double check your gasket, and check the cover. I had a leak problem once with mine, and didn't realize that an old gasket was stuck to the top of the cover. Two gaskets was much too much.

Typical values for a nice, tight engine seem to be about 40 psi or perhaps a tad more, warm at road speed. And perhaps as low as 25 at hot idle, but those I'm familiar with are more like 30 at hot idle.

Those observations certainly don't agree particularly well with the shop manual which says 35 psi at 30 mph.

Interesting. Mine shows about 42-45 consistently, less (of course when I first start it up. But it pretty much remains around 42 warm or cold, idle or at speed. Somewhere I had read that 50 would be even more ideal.

West, are you referencing a 9-main engine? With more leakage points at the extra mains, 9-main engines usually have a higher specified pressure than the 5-main engines.