oil pressure

Ok motor is a-head 557 solid roller in mud truck issue is after 200 foot pass oil pressure gauge bounces around from about 35 to 40psi at start its about 75 kaase oil pump and canton pan with 9 quarts of oil. Give it a little gas and holds steady. No windage tray need some ideas of what can be causing this. Going to cut filter open later this week. Thanks for any help.

If the oil pressure is bouncing that would suggest a lack of oil to the oil pump. I had this problem once but it was all the time, turned out to be a cracked pick up tube. If you are only losing psi at the end of the run maybe you are pumping pan dry and then later at lower rpm catches up ? Just throwing out ideas >

FWIW Mark

557ranger wrote:...a-head 557 solid roller in mud truck issue is after 200 foot pass oil pressure gauge bounces around from about 35 to 40psi. at start its about 75. kaase oil pump and canton pan with 9 quarts of oil. Give it a little gas and holds steady. No windage tray need some ideas of what can be causing this. Going to cut filter open later this week.  Thanks for any help.

The symptoms point to a few possibilites. One of the easiest of them to address first is changing out the oil filter.

Rear sump?

Yes rear sump and have changed oil filter and still did it. The heads have screens in the oil drain backs.

557ranger wrote:Yes rear sump and have changed oil filter and still did it. The heads have screens in the oil drain backs.

Ditch the screens.  Impeding drainback flow in any engine is a bad idea, ESPECIALLY a BBF.

A lotta guys have experienced cracked pick-up tubes on rear sumped Fords. Might check it.

Add another quart of oil. Lifters in backwards?