Oil Pressure Question

93CalypsoConvert · Dec 10, 2020

I recently bought a 93 fox with a carbureted 5.0. The engine was apparently rebuilt, but I do not have proof. It looks brand new under the valve covers and the pushrods are a different brand. My only concern is the oil pressure. Cold idle is 50, hot idle is 15. Its not making any concerning noises. Previous owner claims it has a melling oil pump and new mains. There is no metal shavings in the oil, no copper. 2000 rpm cruising is 40 psi. Measured with mechanical gauge.

Another weird thing is it will NOT go past 50 psi. When cold, it goes to 50 and stops. Cold idle at 800 rpm = 50psi, Cold at 2000rpm = 50psi. Weird

elarm1 · Dec 10, 2020

Is it an electric or mechanical gauge? Or stock gauge?

93CalypsoConvert · Dec 10, 2020

elarm1 said:
Is it an electric or mechanical gauge? Or stock gauge?

Mechanical.

7991LXnSHO · Dec 10, 2020

It sounds like the bearings are a bit worn, but 15 hot at idle will still be fine. How much does the pressure go up as the rpms go up?

93CalypsoConvert · Dec 10, 2020

7991LXnSHO said:
It sounds like the bearings are a bit worn, but 15 hot at idle will still be fine. How much does the pressure go up as the rpms go up?

Goes to about 40 at 2000 and then slows down after that.

7991LXnSHO · Dec 10, 2020

Sounds fine for a worn engine. If compression and leak down tests are good, I’d drive it, saving for or bench building (racing) an eventual replacement.

93CalypsoConvert · Dec 10, 2020

7991LXnSHO said:
Sounds fine for a worn engine. If compression and leak down tests are good, I’d drive it, saving for or bench building (racing) an eventual replacement.

That’s the part that bothers me. It’s a fresh engine. It has great compression. I think the owner put oversized bearings in. Oh well I’ll keep driving it and not try to worry too much.

elarm1 · Dec 10, 2020

send it!

7991LXnSHO · Dec 10, 2020

There’s probably a lot of life in it, and the loose mains are the reason for a new pump. I would not spin it to the moon regularly, but overall it sounds healthy.

Mustang5L5 · Dec 10, 2020

What oil viscosity are you running?

93CalypsoConvert · Dec 10, 2020

Mustang5L5 said:
What oil viscosity are you running?

10w30 synthetic

Steel1 · Dec 10, 2020

15psi hot on a new build is low imo.

HemiRick · Dec 10, 2020

10 PSI per thousand RPM and you're fine.

General karthief · Dec 10, 2020

That's low for a new build.
I'd run it if I had to but it would worry me.

revhead347 · Dec 11, 2020

HemiRick said:
10 PSI per thousand RPM and you're fine.

Correct, you are fine. As long as it comes up off idle, it's fine. There isn't much load on the bearings at idle.

Kurt

marcelo · Dec 12, 2020

with Melling HV Pump it had 60psi ..droping a little when hot at idle ..and now I run a Melling High Pressure and it runs at 80psi at cold idle drops a little when hot at idle ..
10/40 synth.. went back to stock sending unit with low pressure warning light ..

HemiRick · Dec 12, 2020

Thats crazy high pressure just wasting energy heating up the oil.

marcelo · Dec 13, 2020

using the Melling HP pump over the HV ..was recommended by a known engine builder ??!! i dont know .. engine runs great no problems so far ... and no temp problems with oil or engine ... unsing synth oil ..temp doesnt matter anyways..

7991LXnSHO · May 13, 2021

Following the advice from post #2 is a great idea.

Oil Pressure Question

93CalypsoConvert

Active Member

elarm1

93CalypsoConvert

Active Member

7991LXnSHO

wanna catch the space herp

93CalypsoConvert

Active Member

7991LXnSHO

wanna catch the space herp

93CalypsoConvert

Active Member

elarm1

7991LXnSHO

wanna catch the space herp

Mustang5L5

That is…until I whipped out my Bissell

93CalypsoConvert

Active Member

Steel1

Mustang Master

HemiRick

I'd be looking at jacking under the house

General karthief

wonder how much it would cost to ship you a pair

revhead347

Apparently my ex-husband made that mistake.

marcelo

Active Member

HemiRick

I'd be looking at jacking under the house

marcelo

Active Member

7991LXnSHO

wanna catch the space herp

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Oil Pressure Question

Active Member

Active Member

wanna catch the space herp

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wanna catch the space herp

Active Member

wanna catch the space herp

That is…until I whipped out my Bissell

Active Member

Mustang Master

I'd be looking at jacking under the house

wonder how much it would cost to ship you a pair

Apparently my ex-husband made that mistake.

Active Member

I'd be looking at jacking under the house

Active Member

wanna catch the space herp

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