Jeep 4.0 lost oil pressure...

chuck-norris

chuck-norris

Club Member
Last night I was driving home from work and I came to the first stoplight and at idle and the needle dropped the truck has 195xxx miles on it I know the previous owner who never ragged on it he had been driving it for 5 years, I never saw it make it past 3000 miles for an oil change. It did have a slight lifter tick when I got it but what 4.0 with high miles doesn't I'm going to replace the sending unit first but are there any issues that I should know about with these?
 
No, like you said id start with the pressure switch check the oil, and try it make sure there is no coolant in the oil some years were prone to have cylinderheads crack right in the center.
 
I just checked the oil I cant buy the switch yet because im on my lunch break. The oil did not seem milky what so ever but the oil seemed very thin, it is a fresh oil change. I didnt see any metal shavings in the oil and it didnt smell burnt.
 
They both looked to be right on where they should be do 4.0's have anything fuel related going into the block? My mustang used to blow stock fuel pumps and they piss gass into the oil.
 
I just had this problem on my '97 just after I had the oil changed. As I suspected, the oil change monkeys broke the oil pressure sending unit. $20 from Napa, a bit of PB Blaster and 5 minutes later, all was good.

Lemme know if you have ?s. It's an easy fix though. Just be careful unclipping the old one from the harness. The plastic is likely very brittle.
 
DetroitStyle said:
I just had this problem on my '97 just after I had the oil changed. As I suspected, the oil change monkeys broke the oil pressure sending unit. $20 from Napa, a bit of PB Blaster and 5 minutes later, all was good.

Lemme know if you have ?s. It's an easy fix though. Just be careful unclipping the old one from the harness. The plastic is likely very brittle.
Click to expand...

I figured it was the sending unit I let it sit over night started it up oil pressure was great I put some Lucas oil additive in it just for piece of mind and drove it out to out to 696 and 75 and the oil pressure sky rocketed going down 75. It used to sit at 40psi now while I'm driving it goes up to 60 and drops down to 40 at idle.
 
are you useing 5 w 30 or 10 w 30 oil?
read the owners manual 4.0 motors use 10 w 30 in the summer I used synthetic and ran 10w30 year round
 
Just a quick suggestion. The 4.0 is a flat tappet cam so the best oil to use is a diesel oil, rotella is good go to naxja.org and do some poking that is prob the best site for xj
 
You must log in or register to reply here.
Back
Top