Oil Pressure oddity

[Jeff-97XJ]

97XJ, 4.0, AW-4, 231J, 370K miles.

Sometimes when I start the Jeep, the oil pressure gauge shows no oil pressure. The check gauges light comes on. If I press the pedal to the floor, for one quick shot of RPM boost, the pressure comes up to normal and stays that way. This problem is intermittent. It only happens on start-up, and only sometimes.

Any ideas??

Thanks,
Jeffy-97XJ

 

[johnnyc]

I'd replace the oil pressure sending unit. And don't use teflon tape on the threads, because the unit is self-grounding.

 

[Digger87xj]

yup, sending unit. Kinda common.

 

[peuglow]

Not to hijack this thread, but would this unit also cause a high pressure reading when the engine is running? My jeep seems to always have high oil pressure (dummy gauges read well over 'mid range')

 

[yossarian19]

Oil pressure gauge could fail a number of ways. Could read chronically high, sure. I'd verify your actual oil pressure with a mechanical gauge.

 

[peuglow]

Oil pressure gauge could fail a number of ways. Could read chronically high, sure. I'd verify your actual oil pressure with a mechanical gauge.

Thanks, I appreciate the response. I'll go find a place to buy the gauge and figure out how to use it.

 

[Sidewinder CC]

Thanks, I appreciate the response. I'll go find a place to buy the gauge and figure out how to use it.

You can borrow a test gauge kit from several of the auto parts stores, no need to buy one.

 

[Sidewinder CC]

I'd replace the oil pressure sending unit. And don't use teflon tape on the threads, because the unit is self-grounding.

OBDII oil pressure sensors are grounded through the PCM, but it's still not a good idea to use tape on the threads because the tape extrudes and may enter the pressure sensor orifice.

 

[Ecomike]

Change oil filter immediately!!! Get a quality oil filter, NOT FRAM!! I use K&N only.

The drain back valve is probably leaking and draining the oil filter when the engine is off. So start up will eat the bearings, etc faster since the oil pump is trying to fill a leaking filter first!

If it is not the filter or P sensor, then it maybe the pressure relief valve??? I forget where it is located, oil pump or oil filter adapter?

97XJ, 4.0, AW-4, 231J, 370K miles.

Sometimes when I start the Jeep, the oil pressure gauge shows no oil pressure. The check gauges light comes on. If I press the pedal to the floor, for one quick shot of RPM boost, the pressure comes up to normal and stays that way. This problem is intermittent. It only happens on start-up, and only sometimes.

Any ideas??

Thanks,
Jeffy-97XJ

 

[Jeff-97XJ]

I had forgot to mention in my original post, I already changed the oil sending unit to a $50.00 Bosch unit. The original sending unit was giving me low and no oil pressure readings while on a trail ride.

This new Bosch unit only gives me trouble on startup, and only intermittently. As soon as I installed it, I had no more problems during the trail ride, the problem cleared up instantly, but a couple of weeks later I started having this problem.

Thanks,
Jeffy-97XJ

 

[Johnnie Walker]

I would definitely recommend a mech., gauge to verify pressure.

 

[cruiser54]

I had forgot to mention in my original post, I already changed the oil sending unit to a $50.00 Bosch unit. The original sending unit was giving me low and no oil pressure readings while on a trail ride.

This new Bosch unit only gives me trouble on startup, and only intermittently. As soon as I installed it, I had no more problems during the trail ride, the problem cleared up instantly, but a couple of weeks later I started having this problem.

Thanks,
Jeffy-97XJ

If it's on start-up, I would suspect the filter. What brand do you have on there?

 

[ParadiseXJ]

Thanks, I appreciate the response. I'll go find a place to buy the gauge and figure out how to use it.

Not the gauge...the sender.

 

[Sidewinder CC]

Not the gauge...the sender.

I think peuglow was talking about obtaing a direct reading mechanical gauge to test his oil pressure at the ol pressure sensor port.

 

[peuglow]

I think peuglow was talking about obtaing a direct reading mechanical gauge to test his oil pressure at the ol pressure sensor port.

Yes, I should clarify I'm going to borrow a gauge to test the pressure. My readings on my dash gauge has been erratic/high at best

 

[Ecomike]

If it's on start-up, I would suspect the filter. What brand do you have on there?

X2 X2 X2!!!!

I think some one else said that too, LOL!!!