new motor, high oil psi

hey all

swapped a lower mileage 1990 4.0 into my 1990xj. you may recall me having cracks in the block, and i have fixed those thanks for the help.

the motor sat for unknown amount of time before i swapped it, and it had a full crankcase of oil when i got it, i changed it of course

the first few days it had 40psi at startup and then about 20 when driving, little to none at warm idle.

now after about a week of driving it is about 60 at startup, 30 at warm idle and about 60 when cruising. if i coast it runs about 40psi and if i downshift it runs up to 80 psi.

i am running 4.88s and 35"s so my cruising RPMs are a little over 2000 when at speeds

i am grateful to have oil psi, but i dont wanna blow a gasket.

-Tim

From a stock gauge, different sending unit? I wouldn't be too worried with those "relative" numbers but if you dunno what weight oil is in there you should. Change the oil to a known weight and then see what you get?

hey
its 10w40 oil and it is the same sending unit that was in the old motor, i swapped all the sensors over.

-Tim

I say change the filter just to see. Else I would leave it alone.

I would change the oil again to help flush out the ooold stuff and get a new factory sending unit (the aftermarket ones never seem to last or be as accurate). And you don't want more than 60 psi cause it can cause rear main seal to leak if it isn't already and cam/distributor gear wear.

Kyung

thanks guys,

currently there are NO leaks in this 4.0, however it has pretty bad blowby so i was gonna clean out the top end (under the valve cover) and pour in that oil system cleaner stuff, i figure its just gunky down there

-Tim