Whats up guys i have an 89 jeep cherokee my oil pressure has always been at around 40-60 psi on highway and around 20-40 on idle but now all of a sudden its been about 20psi highway and almost 0-8 on idle. I just had the rear main sealed replaced at a shop could this be the reason this is happening? Please any help would be appreciated.

 

It's possible..............They replaced the oil filter when they did they oil pan and seal? I have seen drops in oil pressure caused by incorrect or "cheap" oil filters.
Also could be debris in the oil pickup tube.

 

No the oil filter wasnt changed, at start up i also hear some grinding for a split second what could this be? Could it be the oil pump?

 

It is possible the pump could be going out or it could be bearings either crank or cam,is the oil the same weight as before?
If it is actually that low I would look into soon before it just quits.
i have a mechanical guage as well as the stock one,came in handy more than once.

 

Hopefully its the oil pump, is it difficult to change?

 

Well it is not easy that is for sure.

 

You can get to it by taking the pan off,you need to be sure that you line up the dist with it,it will not go back in unless it is. It is not to bad.

 

i would check the oil pressure sensor before you do that.. i had this happen on my cherokee and i just went to the junkyard and got the sensor. now i am back at normal pressure.
i bet this is just the problem, and its nothing major at all..

 

hope ur right, but why do i hear grinding when im starting the jeep?