I have a 355. When i start it and the engines cold, the pressure of the oil is about 20 psi, however when it warms up the pressure drops to 0 unless i am on the gas. If i am on the gas, it will climb to 20 or 30 psi. Why does it idle at 0? I am getting no ill effects as i have taken my car down the track multiple times. When at WOT it climbs to 40 or 50 psi easily so i don't suspect a bad pump. I have a mechanical gauge so i know it's "correct."

Can an oil filter adapter cause this low reading? When i built the engine 100 miles ago, i got the adapter from a junkyard.

 

Since the pressure climbs when you accelerate I would suspect excessive bearing clearance.

 

Shouldn't be... what effect will that have on my motor long term?

 

If the oil pressure gauge is indeed correct I would also suspect wore out bearings on an OLD engine, but since the engine only has 100 miles on it I would suspect improper assembly or incorrect bearing clearance as the cause, and it may run for a long time or die tomorrow.

 

Who assembled the engine. If you had it built take it back and have them replace it. 10psi for 1000rpm and 5psi for 500rpm is the lowest it should ever be

 

Look at the port plug under (above?) the rear main cap. Check the depth/position to make sure it is not obstructing the oil passage from the filter to the main galley.



What pump are you using? What OIL are you using?

More importanly, why are you running an engine at the track with only 100 miles on it? Unless it was race prepped (polised bores, coated rings, burnished shells, etc.) it would probably appreciate some break-in time before loading.

 

If your main bearings are off by one thousandth of an inch, it will cause low oil pressure...

 

I am using 10w30 castrol. I never cecked that port plug during assembly because, well, i didn't know what it was. I built the engine in my garage. I ran the engine on a start stand and let it idle over night after a 15 minute 2500 rpm run. So i consider that my break in, and i didn't have any problems. I figure if it was gona blow, it would have grenaded by now as hard as i push it.

Like i said, the engine pumps oil adequately when i even barely bump the throttle, but it idles damn near zero. I'd say idle is about 700 rpm.

To answer my other question, is it possible that the filter adapter is clogged or damaged in some way to restrict oil pressure at idle?