83 Wagoneer
AMC 360

Crazy as it sounds - Using a mechanical oil pressure gage - when I rev the engine up at idle, the oil pressure LOWERS instead of raises. Can anyone explain what causes that?

I removed the NAPA Gold oil filter as well as the oil pressure relief valve spring and poppet just to see if something was stuck or blown. I replaced the oil filter with a cheap FRAHM and replaced the same spring & poppet.

Started up the engine again, and BINGO - back to normal
Hot Idle = 20 psi
HOT 55 MPH = 50 psi
Cold = Much higher pressures as you would expect. Pressure increases along w/ RPM as you would expect it to.

Now - After approx three weeks - my Crazy Oil pressure problem is back again. This time I replaced the entire filter adapter & pressure releif poppit with a bulltear unit complete w/ mid-plate. Fired the engine up and No Joy! The "backwards" oil pressure situition still exists.

Any thoughts as to the root cause?

Jeff