The hotter you get the engine and oil the oil pressure will drop . if they did it from a cold engine it does drop oil pressure for a cold engine to a engine running at engine temp. it drops pressure that is normal . I've read your post have you changed the water pump ? I've seen water pumps in jeeps not able to move enough coolant at rpm but will work at idle or just above idle . vary few mechanics have the tools to test water flow . I have the tool and that's why I know that jeeps water pumps can go bad that way .

 

Last post is spot on, high output Water Pump helped mucho in making High Temp issues stabilize for me. The $4.0$ is massive heat pump . I stripped out all my heat shielding and such figured let it blow away. When I stop moving I prop the hood NYC taxi style. Good luck 2 all you good jeepers.

 

Thee water pump has been changed and it is running fine. The oil pressure drops to zero during the test. Two different mechanics agree on the result and neither of them profit from it so I believe them.

 

Why don't fix it ? Replace all the crank bearings and oil pump . it's not a hard job it just takes some time to get done .

 

If I was going to be home I would. I wouldn't hesitate to pull it and either do the work myself or take it to someone else but when I bought the Jeep I wanted a semi reliable additional vehicle for my family. Nobody else in my family is up to the task of working on it.

Anyway, it is resolved. I traded it in (at a large financial loss) to a used dealership and purchased a 2000 Grand Cherokee limited with less than 100k miles. It is in much better condition than the XJ.

I'm going to miss the XJ though. It would have been a fantastic base for a project.

 

Might want to check radiator hoses again. You can`t tell if they are collapsed without taking them off. They collapse on the inside. This is why some radiator hoses come with a spring inside them!

 

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So true. Makes a high pressure flush possible.

Not just good preventative maintenance, it can sometimes cure sudden onset overheating.

It did for mine at 275K or so.