so what should the normal oil pressure be upon start up with these 4.0l engines. I just installed a shelby series 1 engine into my aurora about 2 years ago and I notice now on start up i have oil pressure upwards of 90psi. once warmed up its about 60psi at 1300 rpm and down around 25 at idle. I dont recall what it was when I first installed the engine.
I will change the oil/filter this weekend to see if it changes but 90psi seems high to me. maybe its the shelby motor? I did get an inspection sheet with the engine and it has a bunch of undescribed steps checked off like they did something to it- but it doesnt say what was down. any ideas?
I don’t know what the Shelby conversion would involve. The oil pump bypass spring could have been changed to increase pressure at higher rpms. Your pressure readings look to be inline with that. My 95 Aurora has 70 to 80 cold and 35 at idle after reaching 210 operating temperature. In hot weather after extended running at intestate speed, the oil temperature is at its hottest. The pressure drops at idle to about 22 . I think the 94 and 95 have a better oil pump than the later engines . I don’t know if it’s higher volume or higher pressure. I don’t think oil pressure will be the demise of my car. More likely the head gaskets.