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Oil Pressure + Bearing questions.. 88 4.0 and 98 4.0

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First is my XJ(88 4.0). Right when I start it, oil pressure reads about 55-60. After it warms up, it settles down to 19. I'm hoping changing the main and rod bearings will fix this, but I wanted to see if there was anything else I should tackle while I have the pan off... again.


My brother's XJ(98 4.0) is also having a problem. About a week ago it started a very loud lifter tick, and right when the tick started his oil started staying at 50-55 instead of right at 40 where it's always been. Spun cam bearing maybe? Is there anything we can do to help this without tearing the motor apart?

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Your oil pressure is within spec, if the 19 psi is at idle. Factory spec is 13 psi minimum at idle, 37 to 75 psi above 1600 RPM. Nonetheless, 19 is lower than most, and I believe new bearings would fix that. While the pan is off, you should also replace the rear main seal. Based on your startup oil pressure, it doesn't sound like you need an oil pump.


As to the other vehicle -- recent oil change? Different brand of filter? FRAM filter, perhaps?

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There's less than 2000 miles on the RMS.


19psi is at idle, and when running. It doesn't start to go up until over 3000, at 3500 it's about 35psi.


I forgot to mention in the other post that once in awhile, when I start it up, there's no oil pressure for the first few seconds, then it jumps up to 55-60. And the motor does sound different during those few seconds.


As for the 98, it's not a recent oil change, and he's not using Fram filters. I just recently got him off of Fram.

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