Too much oil pressure?

[35fordtn]

I recently installed a new 50lb oil sending unit in my 40 as well as a NOS gauge. At idle the gauge was pegged out. Tonight I removed the sending unit and installed a mechanical gauge tool to check it. It is showing 70 lbs at idle cold and 110lbs when you rev it slightly. The engine was rebuilt by the previous owner so I have no idea what pump is in it. Could the oil pressure relief valve in the block cause this? Maybe it is stuck?

[big job]

At 110# I would say its the valve is stuck or too heavy spring, most likely stuck.

[Walt Dupont--Me.]

It's probably got a high volume pump or it has real heavy spring in the pump, the trouble is in the pump. Walt

[G.M.]

Originally Posted by 35fordtn

I recently installed a new 50lb oil sending unit in my 40 as well as a NOS gauge. At idle the gauge was pegged out. Tonight I removed the sending unit and installed a mechanical gauge tool to check it. It is showing 70 lbs at idle cold and 110lbs when you rev it slightly. The engine was rebuilt by the previous owner so I have no idea what pump is in it. Could the oil pressure relief valve in the block cause this? Maybe it is stuck?

Adjust the pressure valve in the block with shims to set the pressure in
the 55 lb range. While the manifold is off remove the spark plugs put a
little MMO in all cylinders, cover with a rag to avoid a mess. Install a mechanical oil gauge. Spin engine with 12 volts to the starter. The
pressure you see will be the pressure driving down the road above 45
MPH. G.M.

[35fordtn]

I removed the intake manifold and replaced the relief spring. That seemed to help. Now it is 35LB cold idle, 80LB cold at 2500 ish rpms. Hot it is 20LB idle and 55 at 2500. The spring I removed was longer than a stock spring

[RKS.PA]

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Seems like you've nailed it!!

Dick.

[G.M.]

Originally Posted by 35fordtn

I removed the intake manifold and replaced the relief spring. That seemed to help. Now it is 35LB cold idle, 80LB cold at 2500 ish rpms. Hot it is 20LB idle and 55 at 2500. The spring I removed was longer than a stock spring

The length of the isn't what always determines the pressure. Temper
of the wire, diameter and fatigue are all factures. The best way is with
a shim made out of 1/4" pipe. I start with about 3/16" thick and adjust
the thickness to get the pressure I want. Yours sounds pretty good now. G.M.

[35fordtn]

My guess was someone replaced the spring with a longer one trying to obtain the same result of shimming and seemed to be a failed effort on their part.

[Ronnie]

What oil do you run?

R

[35fordtn]

In this car, 10-40 in my others I run 20-50

[Kahuna]

I think you've got it just right.
Good job

[my4dv8]

At least you are on to it, if you ran with that sort of pressure you sure wouldn't do the bearings any favours. You would be like old lead foot Louie and power blast the bearings .

[Terry,OH]

Michael: You may want to run 10W-30 oil and see if the hot, high RPM, pressure will drop under 50#. If the engine is a new rebuild it will help the break in.

[Bored&Stroked]

The hot pressure numbers you have now are just fine - pretty much what I aim for with most engines.

Not sure what oil pump you have in it - but if it has the late 49-53 pump that many of us run, then you have two oil pressure springs in the car now (one in the front of the block and one at the pump). The original pump didn't have a pressure spring, so the front one was what all 32 - 48 engines used.

A couple years ago, I bought an old original 32 V8 (had been sitting outside for awhile) - when I tore it down, found a 49-53 pump in it. At least I knew the engine was running around that time - only bad thing, they took out the pump baffle in the original aluminum pan so that it would fit. Arrrrrrrrrrrrrrgh.

[DavidG]

Arrrgh is right. Maybe that explains why so many surviving '32 aluminum pans are missing their trays and baffles.

[35fordtn]

Thanks for all the advice. The engine was rebuilt when the car was restored and has 600 miles on it but had sat for 25 years. I am honestly too lazy I guess to pull the pan just to see what pump it has. I plan to use 10-30 next week and see how it goes.

[Bored&Stroked]

Originally Posted by DavidG

Arrrgh is right. Maybe that explains why so many surviving '32 aluminum pans are missing their trays and baffles.

Exactly the conclusion that I came too!

[Terry,OH]

When the 32-34 style of oil pump was replaced by the more typical 50# pump, found in the 35-41, Ford issued a service Bulletin regarding the use of the later pump in the early pans, it involved, in part, the removal of part or all of the early oil pan baffle for the clearance needed for the pump pick up. I am not sure if a later style pump (35-41) could be used in the 32 aluminum oil pan or if there are other issues.

[Ol' Ron]

The biggest problem you have with Hi oil Pressure is the Blasting of the bearings, also in some cased the fillet radius of the cast iron crank can be eroded. This caused crankshaft failure in our stock car engine. In a lightly loaded street engine 10 lbs at idle and 30-40 at cruise. One thing the bearings need is good flow of oil though the bearing for cooling.

[Cheaterpete]

what s the problem with too much oil pressure? I have 90 cold, and 35 to 40 when engine is warm, rebuilt engine with new french army truck oil pump, I run 20w50 oil.

[JSeery]

As Ron stated it is like medium blasting the bearing surfaces! There are no positives to it that I am aware of and a lot of negatives. Short periods of time might not be that bad, but not sure why you would want it that high. If it were me I would switch to a lighter weight oil.

[Ronnie]

Yup^^^^ x2 Can't see any advantage of oil pressures that high.I am not aware of any benefits of having it high.If someone can state advantages of high oil pressure in a flathead lets hear them. Just sayin.

R

[Bored&Stroked]

For a street driven engine with normal crankshaft clearances, naturally aspirated horsepower levels and normal RPM ranges, I can see no advantage of higher pressures and heavy oils. I'd probably run 10w/40w in most engines - with good quality machine work, maybe even 5w/30w.

In a full-competition engine - especially a supercharged one, one will typically run much larger bearing clearances, much higher rod side clearances, heavier oil and a dry-sump system. We need the larger bearing clearances and heavy oil to account for crankshaft flex and load - and with the heavier oils, we'll have high pressure on the beginning of a run (like 110 - 120 psi at 2000 rpm), but by the end of the run, it will be closer to 70 - 80 lbs. (Note: this is at Bonneville).

[Drbrown]

Have 59AB with 80 lb pump; use 10w-30 oil; get 70 lbs cold any rpm; 40 to 50 lbs highway hot; 15 to 20 lbs idle hot.