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my tj at idle sits at 19 to 22 psi and when i am on the freeway doing 60 or so it will sit at 40. is my oil pump going or am i ok. the motor has about 150,000 miles. i am only asking because on my other tj with the 4 cylinder always idled at 40 psi and went to 60 on the freeway.
 

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Mine runs in the low 50's at cold idle. Once it gets good and warmed up, it will idle at about 25-28.
At 2K RPM on the road it runs in the low to mid 50's.
It's a '99 with about 58K miles on it.
I just added a mechanical pressure gauge a few weeks ago after my second sending unit took a dump on me in about 6 months. They're known to be crap on TJ's. But, when they go bad they'll jump all over the place, not just run below where they ought to be.
I know this doesn't answer your question, but a little info for you to use as you see fit.
HTH
 

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You're fine, Specs for a 2003 4.0 say 13psi at idle and 37 to 75 psi @ 1600 and higher. I don't have my other FSM's handy but suspect the specs are the same. Electric oil pressure gauges give approximate readings, put a manual gauge on it if you're still concerned about it.
 

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My 97 XJ 4.0 Auto,,,runs the same as yours. this week passed 149,000 miles and runs like a champ.
 

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[ QUOTE ]
My 97 XJ 4.0 Auto,,,runs the same as yours. this week passed 149,000 miles and runs like a champ.

[/ QUOTE ]

My 93 XJ 4.0 Auto, is about the same, 249,000+ and going strong. Gotta love it!
 

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Those figures are about what my 99 had with the stock oil pump. I put a high volume in ..and I don't think it was really necessary. The 75 limit is to limit the stress on the shaft. In a 4.0 (or any other pushrod engine) the oil volume and the relief limit don't have to have anything to do with each other.

If you want more oil pressure, go to a 5w-40 synth. It will give you a higher pressure then a multi-visc 30 weight without as much start up parasitic losses associated with a conventional 40 weight. Something like Rotella T synth is good for about 10k or a year (make it 6 months for extreme duty) ...maybe more :shrug:
 

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The only thing going is probably the oil pressure sensor...
 

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ive always gone by the old..."10PSI per 1000 RPM" rule, so far ive never blown a motor/ubbthreads/images/graemlins/grin.gif
 
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