I'm haveing a problem losing oil pressure. while running at a mild speed 3500 rpms the oil pressure droped slowly to nothing. I replaced the oil pump and pick-up and bearings(mains and rods) over the winter. now after the engine ran great for 2-3 hours the same problem happened. Am I over looking something? motor is a 454 gen IV mostly stock, Imco Exhaust any advice is appreciated.

what type of gauge electric or manuel if not manuel run a manuel and watch it.could also be all the oil on a high volume pump is pumping so fast your pump is cavitating add an extra quart.

Need more details. Did you check it with a mech. gauge? Does it make any noise when it loses pressure? How do your temps look?

Had a mechanical gauge on it for the first hour checking constantly, not a high volume oil pump , I replaced with a stock one. Water temp is 140-150 no oil temp gauge. First time lost pressure everything started squeeking and clanking around that's why I replaced the bearings.

What is your oil pan capacity??? You also need oil temp gauge. What weight
oil are you running and do you run any type oil thermostat? What brand oil pump
did you put in?

Sorry for all the questions, but will help trying to figure out the problem.

Mike

Oil capacity is 6 quarts, I know I need an oil temp gauge, i'm working on it. running 10-40 oil. stock replacement pump no-name brand. no oil thermostat.
thanks for the help I appreciate the replies.

Do you have a remote mounted oil filter and oil cooler? If you do, is it possible that the oil bypass valve has too light a spring?

What happens is the restriction in the lines and fittings, remote mount filter and cooler add up to more pressure than the spring. The bypass valve opens because it "thinks" the filter is plugged. Hot oil then bypasses the remote lines and cooler, and goes straight back to the engine (without being filtered either). You have no oil temp gauge so you would not see the engine oil getting hotter and hotter.

Thank you Tomcat, I do have a remote Filter and cooler I thought the bypass valve stuck open the first time this happened so I replaced the oil pump. how do I remedy this if it is the problem? but I am running the exact same set-up on the other motor and not having an issue.
and both my manual gauge and dash gauge read about 35-40 psi.

The bypass Tom is referring to is in the oil filter adapter mounted to the block. It's a spring loaded valve that allows oil to pessurize the system if your filter, lines, or cooler is blocked. But this results in iol not being cooled or filtered.
Also, did you replace your cam bearings?

Gary I did not replace the cam bearings. but the engine ran perfect for 2-3 hours before losing oil pressure. why would the bypass fail after so long?