High oil pressure

[Vanspeed]

I just fired my ‘36 LB up got the first time in my Model A. I have a mechanical oil pressure gauge hooked up and it pegs 80lbs on start up and stays there. It is a stock ‘36 pump. Why am I getting such high oil pressure?

[flatjack9]

Oil pressure relief valve stuck or too strong of a spring?

[Vanspeed]

Where is it on a ‘36?

[JSeery]

Toward the front of the lifter valley.

[Vanspeed]

Ok stupid question. I have only started it. Ran for no more than a few minutes because I have no coolant in it yet. 1- should I put coolant in it and run it up to operating temp? 2- can any harm happen while doing this? The engine has not been run in a few years.

[tubman]

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The first thing I would do is get another mechanical gauge to make sure you really have a problem. They are not very expensive and pretty easy to change out.

[Pete]

Engines do not last long when run dry for several minutes. Bad scene.

[KGS]

Originally Posted by Vanspeed

... I have no coolant in it yet. 1- should I put coolant in it and run it up to operating temp? 2- can any harm happen while doing this? The engine has not been run in a few years.

1&2. Just use water initially. In the event you have any internal coolant leaks,
water will do no harm. Antifreeze could damage bearings.

Once you're all squared away, drain the water and add the coolant of your choice.

[cadillac512]

Originally Posted by Vanspeed

Ok stupid question. I have only started it. Ran for no more than a few minutes because I have no coolant in it yet. 1- should I put coolant in it and run it up to operating temp? 2- can any harm happen while doing this? The engine has not been run in a few years.

Yes, that is a good plan and what I'd do. Warming the oil to operating temp will likely make a big difference in the pressure,especially at idle. No way to get it warm enough without coolant in there though.

No, if you run it at a moderate speed (1500-2000 rpm max) and let it warm up even if the pressure is high nothing will suffer. If it's still really 80psi all the time when hot, it's time to investigate.




Terry

[flatjack9]

You will never get the oil temperature very high at idle. Needs to be run hard for quite awhile.

[JSeery]

Originally Posted by Vanspeed

I just fired my ‘36 LB up got the first time in my Model A. I have a mechanical oil pressure gauge hooked up and it pegs 80lbs on start up and stays there. It is a stock ‘36 pump. Why am I getting such high oil pressure?

What viscosity oil are you using and what was the outside temperature when you had it running? I would want to be sure oil is actually getting to the bearing surfaces before running it to heat it up!

[Vanspeed]

I filled it with water and fired it up. It never went past 150 degrees but I did get the idle to go down to around 50lbs by adjusting the idle a little. Still seems high. Maybe a bad gauge but I don’t have another one here to check.

[Vanspeed]

I put shell rotella in it. I think it was 15w40. Temp was about 56 degrees.

[tubman]

I think you're good to go. That's pretty heavy oil for a fresh rebuild and I would bet you didn't get the oil heated up at all, no matter what the water temperature was.

That's also a pretty low ambient temperature. My latest idles at 25 psi hot and runs down the road at 55 psi. And thats with 10/30 oil.

[Vanspeed]

This was not a rebuild. I got the engine from my boss who got it when he swapped out the Flathead for a small block. I checked it all out and it was super clean inside and he said it ran fine when the guy brought it in.

Originally Posted by tubman

I think you're good to go. That's pretty heavy oil for a fresh rebuild and I would bet you didn't get the oil heated up at all, no matter what the water temperature was.

That's also a pretty low ambient temperature. My latest idles at 25 psi hot and runs down the road at 55 psi. And thats with 10/30 oil.

[tubman]

Originally Posted by Vanspeed

This was not a rebuild. I got the engine from my boss who got it when he swapped out the Flathead for a small block. I checked it all out and it was super clean inside and he said it ran fine when the guy brought it in.

This tells me that it was probably gone through at some previous time and does not have a lot of time or miles on it. I still think you're OK to proceed.

Did you check the oil pump? It may have had the later (80 lb) pump installed.

[cadillac512]

Originally Posted by tubman

I think you're good to go. That's pretty heavy oil for a fresh rebuild and I would bet you didn't get the oil heated up at all, no matter what the water temperature was.

That's also a pretty low ambient temperature. My latest idles at 25 psi hot and runs down the road at 55 psi. And thats with 10/30 oil.

Agreed. I say you're ok in the oil pressure dept. I'll bet it runs near where tubman's does when it's in the car with thermostats.


Terry

[Vanspeed]

I swapped out the mechanical Stewart Warner from my truck and at idle I get about 50-55lbs cold.

[tubman]

I believe that shows that it's a good engine, that pushes against the relief valve and forces it open when the oil you are using is cold.