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Oil Pressure oddity

J

Jeff-97XJ

NAXJA Forum User
Location
Atlanta, GA
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
 
I'd replace the oil pressure sending unit. And don't use teflon tape on the threads, because the unit is self-grounding.
 
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')
 
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.
 
yossarian19 said:
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.
Click to expand...
Thanks, I appreciate the response. I'll go find a place to buy the gauge and figure out how to use it.
 
johnnyc said:
I'd replace the oil pressure sending unit. And don't use teflon tape on the threads, because the unit is self-grounding.
Click to expand...

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.
 
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?

Jeff-97XJ said:
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
Click to expand...
 
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
 
I would definitely recommend a mech., gauge to verify pressure.
 
Jeff-97XJ said:
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
Click to expand...

If it's on start-up, I would suspect the filter. What brand do you have on there?
 
Sidewinder CC said:
I think peuglow was talking about obtaing a direct reading mechanical gauge to test his oil pressure at the ol pressure sensor port.
Click to expand...
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
 
cruiser54 said:
If it's on start-up, I would suspect the filter. What brand do you have on there?
Click to expand...


X2 X2 X2!!!!

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