getandistr

So I've been having issues for the past 10k miles with high oil pressure on my Cherokee. When turned on cold it idles at 65-70 psi. When it warms up fully it idles at 55-60 psi and runs at 65-75 psi depending on acceleration. I've used 10w30, 5w30 and most recently Rotella 5w40. I used regular filters and now the Napa 1773 filter. I've changed out the oil pressure sending unit and even tried a mechanical pressure gauge but it showed the same pressure. I've even replaced my CCV hoses as I was getting some oil in my air box.

I have also noticed some oil on the top of my crank case and on my bell housing which I think is from the high pressure forcing it out.

So what could it be that's causin this? What should I do next? And finally should I also replace my seals to fix the leaks or fix the pressure first and see if it continues?

ehall

Could be sludge or gunk blocking a passage

getandistr

From what I read sludge usually causes low oil pressure but the clog seems possible. How would I check for this and how would I repair it?

ehall

Pressure is from restriction, like your finger over the garden hose increasing pressure--flow remains the same so fluid has to go a lot faster in order to dispense the same fixed volume per second.

Anyway, you need to look inside the pan. Its a PITA to drop the pan because the front axle and steering parts are in the way. If you can buy/borrow an inspection camera you might be able to see something through the drain hole. Otherwise its time to get dirty and see whats the problem

getandistr

Is there anything else it could be before I start removing the oil pan?

Firestorm500

Pressure is not created by the oil pump. Like the water pump, it only moves the fluid.

Oil pressure is governed by the clearances on the bearings.

If you do remove the pan, have a brand new factory-spec pump and screen in your hand. The pump and/or screen being the problem is a long shot in this case. If the screen is in fact clogged, or the tube bent, that would only decrease the flow. It would not result in higher pressure on the discharge side.

High oil pressure is increased resistance to flow. The main problem this causes is the oil does not have time to remain in contact with hot engine surfaces long enough to pick up and carry away heat efficiently. A little external weeping is inconsequential compared to this.

Going to 15W-40 is hurting you. You might try 5W-20, which is a little light. Although modern Ford and Honda engines call for this. According to bobistheoilguy.com even 0W-20 is too thick for immediate lubrication on start-up. A few manufacturers do spec 0W-20.

getandistr

Would putting 0w20 be ok? Everything that I've read said not to use w20 in Cherokees. Also I've heard of tricks like running kerosene or atf for 10 minutes to get rid of any blockage in the lines. Does this actually work?

Firestorm500

Split the difference. Try 5W-30. Don't use ATF or kerosene or diesel in your crankcase unless you want to buy some bearings.