Zero Oil Pressure

99xj 4.0l ax15 4 door 4x4 np 231

215,000 miles

As the title says, my gauge has had a mind of its own for 4 years now. For 1 whole year it was pegged at 80 and then dropped to about 40 and then 80 under load. Now for the past few weeks it seemed to be reading normal, and now when it is warm it just says zero across all rpms.

Now I have not hooked a mechanical gauge up to it to verify pressure.

Now for my question about what this motor would sound like if it REALLY had zero oil pressure because this thing run super quiet no tapping, or knocking, the only sound i hear is the faint click of the injectors pulsing.

More info I just moved from florida to wyoming and it is about 15 out in the morning here already this time of the year so i switched to regular castrol gtx 5-30 from running 10-30 in miami.

Edit:
I am going to get a mechanical gauge this week to verify it but im really not losing sleep over this the cap is always saturated and I can hear no strange sounds.

mechanical gauge & verify you have pressure. then, purchase a new sender. You would know it if the engine had no oil pressure. Harbor Freight sells a good test kit for $19.99.

Just change the sender.
I've had them peg high at slightly off idle which is obviously wrong.
Took one apart and it's amazing how fragile and cheaply built they are.

I recommend buying your sending unit directly from Jeep for the best reliability/accuracy/mating with your factory gauge.

Yeah, I had mine peg the gauge for a week then go to 0 on my 99, I replaced the sensor with one from Napa and it's been fine ever since.

yea it did it after switching from 15w40 in super hot Miami daily driving in traffic, to me moving to Wyoming and switching to 5w30 for the super cold weather. I figured a motor with 215000 miles with true low oil pressure would make a lot of racket but this thing whispers.

Common experience suggests it's the sensor.

BTW- You ain't seen COLD yet! But the 5W-30 and a new battery and clean terminals is about 80% of the battle.

2X_01_Jeeps said:

Common experience suggests it's the sensor.

BTW- You ain't seen COLD yet! But the 5W-30 and a new battery and clean terminals is about 80% of the battle.

Click to expand...

Yea it was the sensor all is well. I replaced the terminals and wires not to long ago with high grade stuff. Battery is a year old. Its supposed to be 7 on sunday.. its only november.