I have a loss of oil pressure after the engine gets good and hot. I have replaced oil sending unit already. Next i replaced rods and main bearings. Only one was close to out of spec. rest were decent. but i went ahead and replaced all while i had the oil pan off. Only thing i can think of now could be cam shaft bearings. any ideas??? anyone have this same problem? when the engines cold it runs around 45-50 psi then it will drop to around 10 at a stoplight. if left idle when hot loses all. but doesnt knock or an funny noises. I'm at a loss.

 

the guages on 4.0ls arent that accurate you are fine that ussally run around 15-20 idling you are fine. IT NORMAL!!!!

 

think i should put a mechanical gauge on it to be sure?

 

That would remove all doubt.

 

I would agree that a mechanical gauge would be best. I have seen jeeps and Dodge v8's loose all oil pressure and it was because of carbon deposits for not changing the oil regularly. On the jeep we ran a quart of trans fluid, "dextron" to 5 quarts oil. We ran it for a while and changed the oil, then repeated. When the oil gets hot the tranny fluid cleans the engine and all the deposit comes out in the pan. On the Dodge there was so much sludge that the oil pickup was clogged and when the pan was removed it was chuck full also!!! The guy had to go back and sue the seller because he just bought it a few days earlier. I have a '01 xj and it runs around 15psi when hot and my '98 used to run at 20psi but I feel it's just the gauge.

 

hows your coolant level? Some of the 00 and 01"s had a casting issue with the head and would crack between 3 and 4 coolant would leak onto the cam( right by the oil sending unit) and cause low oil pressure. I would check with a mechanical guage just to be sure. when you had the pan off was there any metal??

 

coolant levels fine, i've had it since last fall and its not used any coolant. There was a little metal, not much. not enough to make me worried with a 154,000 miles.