Quote:

the oil pump has a by-pass plunger and spring for that reason

filters may have an anti-drain back valve but never seen a pressure by-pass on one.



Have you cut a oil filter apart? If not do so The spring and steel flap are the internal high pressure by pass, the rubber flapper on the top is the anti drain back


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)