I noticed on Friday that my oil pressure gauge was reading low (0-30 psi) during normal driving conditions as opposed to the usual (30-60 psi). I checked for any signs of leaking. No puddles or drops were visible. I also checked my oil level and it was just under the "L" mark. So, I filled it back up to the "F" mark. I drove again today and was sure to pay more attention to the behavior of the car. At first I was reading normal oil pressures, but about the time that the car was fully warmed up it dropped back down. I've checked a few times for any visible leaking under the car, including after sitting for a long time and after a drive with the engine still running. There has been no evidence of leaking underneath the car.

These symptoms lead me to believe that there is some sort of seal fracture in the engine that only leaks under normal operating temperature. But it could also maybe be a blockage. So my questions would be...

 

I had a similar issue. My pressure would rise if I reved the engine but at steady loads at temperature it would drop. In my case it was the sending unit. Get an adapter and run an autometer.

If you are on a budget try removing the sending unit, drain the oil out, and reinstall it. I have a feeling air bubbles or foamed oil (from running low on oil) gets in the sending unit and makes them act up.

 

that or the thermowax bypass pellet has failed

http://fc3spro.com/TECH/HOWTO/OTB/otb.html

 

The stock gauge/sender aren't all that accurate. You need to test with a mechanical gauge before jumping to any conclusions really. The bypass pellet shim should be left as a last resort. If you do it wrong, you'll drop a torrington bearing and end up pulling the front cover to fix it.

 

+1 I run a mechanical gauge.. Dont trust the factory sending unit.

 

Not to hijack but under normal driving conditions my cars pressure gauge reads ok. Only at idle does it drop very low and just above the 0 mark. Give it some gas and the pressure goes up. It's been this way since my rebuild 10k miles ago. I've been concerned it's something with the front cover but don't know where to look really.

 

First thing to do might be to remove the single wire connector to the oil sending unit and clean the contact inside as well as possible and put some diaelectric grease in it when reconnecting. Sometimes the connector can loosen over time or become filled with oily grime which can prevent a proper signal from being sent to your dash gauge.

 

Second would be to replace the factory sending unit, it leaks internally and its just garbage..If that doesnt work, get a mechanical gauge. Was my FIRST mod to my car and always will be for the future.

 

the most common causes of low oil pressure are mistakes during an engine build (low oil pressure would be noticed immediately) or a failed thermal pellet. If you don't have an original or reman engine, you probably don't have a thermal pellet because most builders eliminate it.