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Discussion Starter · #21 ·
Problem Solved!

Removed the pressure relief spring and piston to check them out and reinstalled them. All looked fine. Fired her up and oil pressure gauge pegged.

Looonnng time ago my father changed the oil pump base plate and saved the old one. I asked why the change and he couldn't remember the reason. So I dug out the old plate and it too was the later version. Removed the relief valve. Spring in this cavity was considerably weaker than the one I just removed from the pump on the car so I installed this weaker spring and piston.

Cold oil pressure at idle gauge indicates 40. With 'some' temp in the oil, at idle, pressure indicates 10. Needle never exceeds 40 now. Casually took the car around our 3 mile block (45mph) and stopped to inspect. Fuel pump and everything around it dry. Drove the circuit one more time with a lot more rpm (5k) and parked it. Fuel pump and surroundings dry. No more oil leak at the fuel pump.

Thnx for the specs on the pressure sending unit thread size.
 

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I'm curious what oil pressure readings your GT's run. Mine runs:
3.7 @ 2000 RPM and above at normal engine temperature
2.5 @ Idle at normal engine temperature
I have the late model oil pump cover, (pressure relief in the cover)
 

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Discussion Starter · #23 ·
From what I could see this evening out on the interstate between 3,500 and 4,000 rpm it was 3.5 - 4.0. Idling indicates 1.0 and rock steady.

The removed spring (the stout one) had what appeared to be tan or flesh tone paint on it as some type of identifier. I wonder if this spring belongs in the timing cover relief valve bore and somehow made its way into this pump decades ago.

Engine without doubt is not working as hard as it was. Gained a pony or two. Wonder how much oil pressure the engine was getting at 5,000 rpm?
 

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Hi Pressure!

With the relief valves jammed shut - or not there (using front cover and pump cover together, without either relief valve) - the gear pump used for pumping the oil can reach pressures up to 1,500 psi - or 100 bar :eek:

Enough to blow the oil filter off and/or remove the press in oil gallery plugs .......
 

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Stock OP gauge markings . . . BAR

wood95ss said:
Problem Solved!

Removed the pressure relief spring and piston to check them out and reinstalled them. All looked fine. Fired her up and oil pressure gauge pegged.

Looonnng time ago my father changed the oil pump base plate and saved the old one. I asked why the change and he couldn't remember the reason. So I dug out the old plate and it too was the later version. Removed the relief valve. Spring in this cavity was considerably weaker than the one I just removed from the pump on the car so I installed this weaker spring and piston.

Cold oil pressure at idle gauge indicates 40. With 'some' temp in the oil, at idle, pressure indicates 10. Needle never exceeds 40 now. Casually took the car around our 3 mile block (45mph) and stopped to inspect. Fuel pump and everything around it dry. Drove the circuit one more time with a lot more rpm (5k) and parked it. Fuel pump and surroundings dry. No more oil leak at the fuel pump.

Thnx for the specs on the pressure sending unit thread size.
If you're talking about marks on your OP gauge, each mark on the OP gauge is actually about 15psi (BAR = 14.6), so 4 BAR is about 58psi.

Looks like somehow the "TC regulator bypass spring" ended up in your OP cover regulator, but your OP mystery is solved and that's the important thing. :)
 
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