avroman69

I have a 2000 Cherokee sport with low oil pressure. It starts out fine when the engine is cold but once it warms up to operating temperature it drops to nearly 0 psi. It comes up to about 10 psi at 2000 rpm but quickly falls when the rpms drop. I have verified this with a direct reading gauge on the pressure sensor port. I have also had the main and rod berings replaced, and a new head was installed prior to me buying the Jeep. It has been like this for nearly two years with no problems.

Any ideas of what else it might be?

Drive it till she drops!!!

bigdan

what`s the mileage on the 4.0L ?


if you changed the bearings there shouldnt be any reason for this t occur ....

the direct gauge did give the same readouts?

avroman69

Yes the direct reading gauge reads the same... when it is cold pressure is about 40 psi but once it is at operating temp it drops to next to nothing and comes up to about 10-20 psi at 2000 rpm, the Jeep has abot 150,000 miles. and the oil pump has been changed to a high volume pump. Could it be the Cam shaft berings? and if so how hard are they to change?

bigdan

camshaft bearings are less important then main & rod bearings as far as oil pressure is concerned .....quite amazed that even after bearing changed & new oil pump that you have this problem ......and you say that you double checked with a mechanical gauge , and that it gave the same readout cold & warm!

the camshaft bearings would have to be worn a lot to change the oil pressure that much
first time i face a problem like this

normaly when an oil pressure goes down when engine is warm ,it is a sign that the bearings ( main & rods ) are too large ( .003+)

you did verify your clearance with plastigauge when you changed the bearings, did you ?

Dan