73/911 To much oil presure????

[retrotech]

HELP! I have a 73 Cis 911T. It has too much oil pressure. 60# at idle, pegged at 4k rpm. We have replaced both oil release valves with new, new oil thermostat, tried different weight oil, replaced sending unit, and verified with mechanical oil presure unit/
Ideas?

[jmcn3rd]

I am no mechanic but my 72t was also pegging the pressure gauge needle at one time (both cold and warm engine temps) and it turned out to be a cut in the wire between the sender and the gauge.

[retrotech]

thanks, but we have verified with mechanical gauge

[HarryD]

Hi Retro Tech.

Haven't I seen you elsewhere?

Sounds like a problem a fellow is having on another BBS. I like solving mysteries like this.

Anyway, high pressure fluid in pumped systems comes from clogged lines, failure of the pressure relief system or a failure of the bypass at the oil filter.

Do you have high pressure when the car is cold, just when hot or all the time?

If ok when cold but not when hot, I would look around the oil filter and tank.

If high all the time then a plug in the oil circuit or a failed or plugged pressure relief valve would be my suspect.

If high only when cold then a failed or plugged pressure relief valve would be suspect.

This diagram (Thanks Early_S_Man) may help:



Much interesting discussion here to help you fid your problem:
Need help creating external oil cooler system on 1972

[retrotech]

Yes I was asking on the s chat line. I started with super low oil pressure, and too hot. My mechanic changed the thermostat, put in heavier oil. The next day it is started and has 70# cold, 60# warm at idle, pegs at 4k. All of the relief valves replaced, new sending unit. Checked with mechanical gauge to verify. Taking it to another mechanic as this one has no idea what to try next. The most educated long time engine builder in Portland has seen this twice. One was after market filter came apart into oil system, the other idea was a main bearing spun, coverring oil hole? This is the first time I have ever had a problem no one could diagnos? The engine runs fine, no smoke, no noises?

[HarryD]

retrotech,

They way I see it, the oil pump is a positive displacement pump which means it will do everything in it's power to move a fixed amont of liquid through the system. This means that if the passages are blocked, the pressure will rise until a seal gives way or the fluid flows. The symptoms you are describing sound like the relief circuits are plugged since they should be wide open at about 60 psi. I am no expert in the oil circuits but it appears you will need to disassemble the relief circuits (disassemble engine perhaps) to see if they are blocked.

[retrotech]

That is exactly the bad news I am expecting. I am a Vintage Porsche dealer of 35+ years. This car was purchased for resale. I paid for a pre purchase inspection at Euro Tech Ltd., in Incline Village, Nv. The guy is eaither a crook, or a piss poor mechanic. He mentioned some oil leaks, and a front rotor. Didn't mention the fact that it was undrivable, due to rats nest behind fan, fuel mixture so rich, the oil was contaminated with fuel. Poor syncros, and over heating, low oil pressure that now has become high oil pressure. I never would have bought the car, or paid as much as I did, if I had known any of this. This is the first problem 911 I have ever purchased. All because of non professional PPI!! I wouldn't let that shop do an oil change, let alone mechanical work. Maybe he owed the owner a favor? I will have way more in the car than its worth when this is over. But someone will get a well sorted 911. It will be right befoer its sold.

[HarryD]

Retro,

I know you will do the right thing. Hopefully, your pain will be minimized. BTW, your shop is very nice and the route to the Dalles is top notch.

[retrotech]

yes I will, stop by and introduce yourself. Drive old Smokey!