Oil pressure question.

TJ Apex · Posted: Tue Dec 01, 2009 10:18 am Post subject: Oil pressure question.

I have a weird situation going on with the oil pressure on my 4.0. At idle the oil pressure is pegged at 80 psi, then when I rev the engine to 3000rpm the pressure goes down to 40, if I rev higher the pressure drops to 0 and the "check gauges" light comes on. There’s no weird lack of oil noises coming from the engine.

I have changed the oil, and checked the oil level several times and it’s full.
The only thing that comes to mind is the oil pressure sensor.
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2002 Wrangler Apex
Why do I have to press one for English?!
Welfare recipients should pass a drug test to get paid…

02' Apex Edition,
2" BB, 31" BFG AT's

FARMER · Member Joined: 29 May 2007 Location: Benicia Ca.

My ZJ started doing that just before the sending unit started leaking, I think it was leaking under pressure, I just couldn't find the leak while I was looking for it at idle.

Orangeamc13 · Posted: Wed Dec 02, 2009 9:25 am Post subject:

Sounds like it could be the oil pump.
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TJ Apex · Posted: Wed Dec 02, 2009 11:55 pm Post subject:

I have been thinking the same thing, but I really don’t want to tear in to the bottom end.
I have changed the rear main seal of a 96’ 4.0 in a Cherokee about 10 years ago, and if I remember correctly, after dropping the pan, the oil pump looked pretty easy to get at.
I don’t know a lot about the 4.0’s, but what would make the oil pump go bad?

If it is the oil pressure sensor, where is it located? I misplaced my repair manual.
_________________
2002 Wrangler Apex
Why do I have to press one for English?!
Welfare recipients should pass a drug test to get paid…

02' Apex Edition,
2" BB, 31" BFG AT's

FARMER · Member Joined: 29 May 2007 Location: Benicia Ca.

The oil pressure sending unit is right above the oil filter.

TJ Apex · Posted: Fri Dec 25, 2009 9:25 pm Post subject:

I gave my jeep a Christmas present by changing its oil early. The pressure is still pegged at 80lbs, the engine still runs strong, oil looked fine, no metallic shards, and no weird noised when I drive.
I’m hesitant to pull the pan. I’m thinking it’s the oil pressure sensor.
_________________
2002 Wrangler Apex
Why do I have to press one for English?!
Welfare recipients should pass a drug test to get paid…

02' Apex Edition,
2" BB, 31" BFG AT's