None to low oil pressure

[73Runner4spd]

Looking for possible culprits in my loss of oil pressure. Its a 400 big block that I run 20w 50 in. Until recently it always held around 60-65 psi cold and when warm it would drop to around 45 psi at idle. It would also go up around 10 psi per 1k rpm Seemed great. Recently at cold idle it stays around 40 psi and warm it drops to 15 to 20 psi sometimes down to 0, when this happens it struggles to stay running. It also no longer goes up 10 psi per 1k rpm, now it goes all over the place but will not go above 40 psi. It will go up to maybe 40 and drop even under power. I don't know if its the pump, a spit out lifter, or what. Just looking for other possibilities and if anyone has ever seen this behavior before, Thanks guys

 

[nothingbutdarts]

Pressure regulator bad?

 

[RustyRatRod]

Is it full of oil? If it is, you need to verify that the gauge is right. Get a manual oil pressure gauge and install that temporarily under the hood. If it really has low oil pressure, try an oil change and a new WIX filter and go from there.

 

[73Runner4spd]

Is it full of oil? If it is, you need to verify that the gauge is right. Get a manual oil pressure gauge and install that temporarily under the hood. If it really has low oil pressure, try an oil change and a new WIX filter and go from there.

I have a mechanical gauge hooked up. Its what I've had all along. It is full with oil but I do have a leak I believe is coming out of the rear main...easy enough to replace the seal?

 

[70rr-brian]

Rusty's comments I assume were directed at the gauge being the most likely culprit. If not the gauge then a collapsed oil filter can cause the issue you are seeing. Could also be the sending unit to the gauge or the line between unit and gauge. If none of those things are bad then the only other possibility in my mind would be the pump itself...and don't get Rusty started on it being a bad pump. A rear main leak shouldn't be causing your problem unless it is all (oil) dumping out in short order which it doesnt appear to be.

 

[milit73]

I just had this happen to me but I lost pressure pretty quick then lost all pressure. I thought at first the gauge was a problem plus I changed out the sender but did not change at all. I changed out the pump (now 60 psi at startup and 45 psi warmed up) now everything seems fine but have only drove the car 20 minutes after the problem. I am not sure if I have more problems internally but now it seems ok. There is a tread that I started with some more infor. "oil pump failure" is what I called it I think

 

[mattsinger]

have you drained the oil and opened the filter up looking for any signs of metal?

 

[charger360]

one thing is for sure you don't want to run it much at all till you figre it out! it is easy to change a pump on a big block, they are cheaper than the engine! try a filter if that does not do it try a pump if it is still bad.... it could have been hurt but until you eliminate the easy and obvious stuff you just don't know. good luck man!

 

[Hemi Rebel]

Does it make any noise when you start it? Does the motor tick or knock? I wouldnt recommend running it anymore. I would pull the dizzy and oil pump drive and use a priming tool connected to a drill till you figure out whats up to avoid major engine issues.

 

[73Runner4spd]

Not one bad noise at start up or while running