My GF's been driving the XJ for the past month since I put a new motor in my Grand Prix GTX. I drive it on the weekends just running around town. I noticed this weekend that the oil pressure gauge gets up to 80 and over as the RPM's get up there. Before this she ran perfectly at 40 and increase a little bit with RPM's but no where near 80. Common problem? Bad oil pump? or something else.....I'm not the best at diagnosing and this is my first XJ with a 4.0 HO so I'd love to get some input from real jeep guys before I get an opinion from one of my techs at the shop.

 

Yes it is a very common problem. Your oil pressure switch just above the oil filter is either going bad or it is plugged full of crud.

 

ahhh sounds about right. My buddy snapped his off on his '99 sport last time he changed his oil and now his needle is all over the place. I know mine is all covered in mud, the previous owner never cleaned off any mud. I'll just replace it and start there.