1973 Cis 911 Too Much Oil Pressure

[retrotech]

I am at the end of my rope. I have a 73 1/2 911T. It was showing very low oil pressure, and to high oil temp. After replacing thermostat, checking timing, new sending unit, etc. The next day we start the engine, it now has 60# at idle, up to 140# Both pressure releif valves have been replaced. I need HELP!

[YTNUKLR]

Did you put in new oil pressure relief valve springs? Might consider shortening one or both just a tad. I tried this once (fresh springs on hand in case it didn't work), I just cut off about 0.5" from the bottom one, flattened the end as well as I could. Oil pressure dropped to 70# warm @3000rpm.

[retrotech]

That still sounds like allot of oil pressure. I have been told by a 911 authority that the only times he ever heard of this, was a cheap oil filter came apart and blocked some passages, or a main bearing has spun, covering the oil hole?

[304065]

What does the pressure measure when you use a mechanical gauge, not an electric one?

Have you had the oil bypass mod done? What did the "oil pressure relief valves" look like? You know that there are two different pistons, springs, a spring guide and different caps, right?

[retrotech]

Oil pressure is the same with mechanical, as elec.
The relief valve on side has 4 holes around the edge. I didn't see the other one before it was installed. One came for Porsche, the other from Pelican.

[Eagledriver]

The relief valve with 4 holes is for an old style oil pump without the bypass mod. If you have the bypass mod then you need the updated pressure relief valve (no holes and looks like the other piston). Spring is different as well.

-Andy

[retrotech]

I just called Porscxhe dealer with part number of the spring & cup. He confirmed thjey were correct, and that both same, l bottom and side. What oil bypass mod? Tyhe one on the side is the only one I saw, and it was the same as the one removed?