Looking for some help from Jeep lovers !

[hudson2000]

I have a problem with my 1999 Jeep Cherokee. It has 177,000 miles, 10w30, 4.0 I6, 2x4. My problem is when I start the engine the oil pressure is where it should be. When I drive for ten to fifthteen min and the oil heats up and then I come to a stop or place the Jeep in park the oil pressure gauge drops to zero. There is no noise in the engine and no knocking that I can hear, the check gauges light comes on. When I put it back it drive , the gauge jumps back up where it is suppose to be and the light goes off. I change my oil every four to five thousand miles, rotate my tires, check fluids every other week.

Can somebody help me make sense of it. Or what they think I should do ? Thank you in advance.

 

[jeepgeek2002]

http://www.ehow.com/how-does_4778942_troubleshooting-oil-pressure-jeep-cherokee.html

 

[shaggybob]

An external mechanical gauge is a good place to start. Either temporarily run it in to the cabin or just mount it under the hood, then stop and check it.

If the pressure is really dropping that far out though, you should have some fairly bad noises coming from the engine. Since you don't it's probably Ok.

I went through oil pressure issues with my 95 and ended up doing an oil pump and crank kit.

While all that was going on I could really on find 2 specs for the 4.0 oil pressure, both should be measured when warm:
1. at idle it should be over 15 psi
2. At 1850 RPM should be over 37.5 psi

Verify what you've got with a mechanical gauge, borrow one or buy one, they are cheap, and if you're good according to it, probably just a sending unit or gauge issue. there should be specs around somewhere to measure the sending unit with a meter.

 

[Team Willys]

Melkor has had issues similar to this, his sender was bad.

I agree wit Bob, if the rockers dont start ticking (from lifters collapsing) when the gauge drops, then you are probably ok.