I have an old Willys with a 1976 Buick V6 231 cu. in engine. Don't ask how many miles (no speedo) but it runs fine and is quiet. I had a gauge that sends oil from a fitting on the block to the gauge. It read 40 psi at start up when engine was cold. After it got hot, it would read 10 psi at 3000 rpm and 0 to 5 psi at idle speed. I wasn't confident the gauge worked properly as the engine was quiet and ran great. I replaced the gauge with one that had an electronic sending unit. I still get 40 psi on start up,but after warm up I get 25 psi at 3000 rpm and it's still 0 to 5 psi at idle speed. I've rebuilt the oil pump (clearances are spec. and I primed the pump with petroleum jelly as per instructions), I've replaced the oil pick-up tube and screen and even tried 15W-40 instead of 10W-30. No change in oil pressure. When I pulled the pan there was no evidence of sludge. Can the oil pressure really be that low with no noise? Are my bearings worn out? How about an internal oil leak?

Gerry

My memory tells me the lifters need 7 lbs to stay quiet.. If the lifters don't complain I'd forget about it.
As long as you get 20 lbs or more at driving rpm you will be ok.
My first guess would be cam bearings are worn...but that would only be a guess.
The guy that owned my new Jeep put 115K on it with 40W! The only 30W it ever had was from the factory. Seems he had a fleet of trucks and used the truck oil in the Jeep.. You could try a change to 40W to see if that improved the pressure at idle if it bothers you..and it seems it does.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

hmm i had this problem with my jeep in the summertime only at idle it would drop to about 10 psi and then go up to about 40 at about 2000 rpm. i was told it was fine that all the sending units read wrong under high humidity. about a month after that my engine started making a ticking noise that no oil will get rid of and it also has piston slap now.

My guess would also be worn cam bearings. It should be at a higher oil pressure. The engine may seem happy for now but that won't last. Could also be an internal leak, how is the oil level after sitting? After running?

Oil levelis normal after sitting and running. I went to a GM dealer. The service guy said they build brand new V6 engines that have only 3 to 8 psi oil pressure at idle speed. He said 25 psi at running rpm is nothing to worry about. I don't know who to believe. Thanks for the responses.

Gerry