2001 XJ with a 4.0/automatic. After it is warmed up oil pressure at idle usually drops down around 20 on the gauge. If I give it a few rpms it bumps up.


This morning on my way to work I stopped at a red light and it dropped to zero. I tapped the gas pedal and it came up, but seeing no pressure indicated freaked me out.


My first guess is the oil pump. I found a post on a Jeep forum where a guy described a similar problem, but changing the pump did not correct it. He was still trying to figure out the cause.


Any thoughts?

 

Check it with a mechanical gauge. If the pressure is still that low I would consider saving for a rebuild and running a thicker oil in the mean time as you likely have a bearing somewhere that is toast.

 

I agree with the mechanical gauge check.

However, thicker oil is not a solution, even short term. If you truly have an oil pressure problem, find it and fix it quickly. Oil pumps usually last the life of the engine, if not longer. That's why the other guy didn't fix his problem by replacing the pump. It wasn't the pump in his case.

Do you have any, even a little, of unexplained coolant loss?

 

I meant it as a bold over for a worn bearing until you can afford a rebuild. I know its not a solution.

 

NO,NO. Your correct about worn bearings causing low oil pressure...BUT the reason the pressure is low is because there is less flow restriction. Less flow restriction is a GOOD thing for worn bearings....it means MORE oil is flowing through the worn bearings. Thicker oil will make the gauge read higher for a "feel good" effect and thats all.

 

Any oil pressure readings out of whack must be verified with a mechanical gauge, as the others have mentioned. This is the first thing any good shop technician would do if you brought it into a shop.

Very simple. Remove the oil pressure sending unit, install the gauge and you'll know for sure. You can often rent this gauge very inexpensively at parts stores if you don't have access to one; call around for availability

Post the results and we can go from there....

 

I actually just had this problem and found out it was my oil pressure sensor. As soon as I when to remove it, it came apart in my hand.

 

What oil/filter are you running?

 

Go to lowes or hardware store and buy a well-pump pressure gauge that has 1/8 NPT threads......less than 10 bucks!

 

X2 on the sensor. I was lazy and it was winter so I let a shop do an oil change...they mistakenly unplugged the sensor. When I started it with zero pressure, I freaked. Popped the hood and saw the wire, plugged it in and all good. That's just another reason to change your own oil I guess. Good luck!