Hello all, first post despite being a long time visitor of this forum for advice. Before telling me to "search other threads" about my oil pressure issues, I am fairly certain this one has not been completely solved before.

For a year now I have had my 92 Cherokee Sport 2 Dr 4.0L 165k miles and I am immensely in love with it. It has been relatively problem free despite me hauling it up and down the many 14ers of Colorado. However, two weeks ago, I noticed my oil pressure would increase with throttle application. For a year, my pressure would always stay at a perfect 40 psi and not move AT ALL. But now when I accelerate, it jumps to 60 psi and then down to 45ish when off throttle. Weirdly though, even when I floor it, it would NEVER go above 60 psi.

So I changed the oil using Valvoline 10W-30 High mileage (the only oil I use) and replaced the filter as well. The other day I noticed that immediately after starting the engine the pressure was 60 psi and would not go down to 40 until 10 minutes after driving. Once it went down, it would simply go back up to 60 psi with throttle but never once past 60.

So yesterday I changed the oil pressure sending unit and still no change. Very confused. I do smell slight oil burning and the rear main seal leaks slowly like most Cherokees but my oil levels are fine and consistent.

I am dreading to hear I need a new oil pump or anything of the likes.

I am joining the Air Force in a few months and was hoping to not put any work into my Cherokee at all, and then after a few years of saving money do a total rework, paint job, engine swap, axle upgrade, the whole 9.

Sorry for the extreme length, but, any advice?

 

You could have a bad oil pressure gauge.

 

Yeah, try screwing a mechanical gauge into the sensor port and see if it reads like it's supposed to. If it truly is going high, it may be the oil pump relief valve being stuck.

 

Mine was all over the place at one point and would even go down to 0 from time to time, but it always ran the same. $40 for an oil pressure sending unit fixed it for me.
Edit: Sorry I at first only read to the part that said you changed the oil I didn't see that you said you have already changed it.