Mechanical oil pressure regulator 3.8

[Ruurd Schut]

After complete revision of engine, all bearings, new crankshaft sealing system, pistons, head etc. etc.
I have a problem with the oil filter head, the valve opens at 50lbs, oil pressure drops to 20lbs, the valve does not close again until the engine is turned off and cooled down. Engine runs very smooth and is very quiet but this is very annoying.

It is hard to believe that the oil filter head itself is the problem, but offers for a known working filter head are welcome, ready to pay in order to get the car on the road again....

Does someone recognise this problem ?
Thanks for your support
Ruurd Schut

[mgcjag]

Lots of info here..Worth looking.. viewtopic.php?f=4&t=19209&p=155856&hili ... ve#p155856

[DWW]

Are you using a mechanical pressure gauge or relying on the car's gauge?

[abowie]

Pull it apart and check the spring. You can shim it if necessary.

The "spider" in the valve can jam if incorrectly installed, this might be your problem.

Notes from my service spreadsheet:

Oil pressure relief valve spring.

Measured at 9.5lb/in

Spring is 2.00 long.

Compressed length in housing is 0.75"

So calculated to need 12lb to compress it. Used kitchen scales and rod. Almost EXACTLY 12lb needed to move valve.

Hole is about 0.450. Area is 0.160in2

So cracking pressure is 75psi which is within the ballpark of 20% over for 60psi.

QED.

Installed 2 60 thou spacers. Increased pressure by around 10 psi

[Ruurd Schut]

Thanks for the information, again this forum is very helpful.
I will chekc all dimensions and continue from there.

Ruurd