I thought that I may have seen a similar question before, but could not find it.

I have 74 Dart that I recently bought. Previous owner claims the engine, a 360, to be "Rebuilt". Here's the problem:
When it is first started, oil pressure is about 50-lbs. As it warms-up, the oil pressure begins to drop as the temperature rises. By about 180-degs, the oil pressure has hit zero. Compression is good, as is vacuum and there is no blow-by.

Any suggestions?

THANKS

Zero psi is never good, my first thoughts are is the engine noisy and are you sure you have a properly working gauge.

If indeed you have 0 pressure and hydraulic lifters they would be rattling to beat the band. They will be the first thing to make noise.

If you're lucky the oil pressure relief valve in the oil pump is stuck in the open position or someone forgot to replace the 9/16 cup plug in the oil passage that separates oil going to the filter from oil leaving it when the engine was rebuilt. You can check the plug by removing the oil pressure sending unit and sticking a coat hanger wire down the hole. The wire should bottom out between 71/2 in.-711/16in. from the deck if the plug was installed correctly. If the plug is missing, you will have to pull the pan, oil pump and rear main to replace it. If its the pump, the rear main stays in place. If its not one of these I think you may have a real problem. Good luck and let us know what you find.

I'd R&R the pan & throw on a new oil pump EDIT but do open it up & clean it w solvent/check clearances & oil it & dont use a gasket between the oil pump & main cap even if one is included.

Thanks for the replies!!!

Noise: When the pressure is about to bottom out, it almost sounds like a light rod knocking.

Guage: It is a fairly new Sun-Pro mechanical guage, I'm assuming it is working properly.

I'll try the coat hanger test tomorrow ater I do the brakes on my In-laws T&C Van.

Thanks again!!!