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Oil pressure issue

dirtyjerseyjeep

NAXJA Forum User
Location
new jersey
So when my jeep is cold oil pressure is great once it warms up it drops and when I stop the gauge drops to zero, what do you think my issue is and how can I fix it?
 
The factory gauge is not really all that accurate. Before you do anything, put a mechanical gauge on it and see what's actually happening. However, you will probably find that the oil pressure is lower overall than most "specs" say it should be, depending on the age and mileage of the motor and how well it's been treated by you and previous owners.

Is there something else that causes you concern about the motor, or does it run fine as is? If so, keep driving it until it blows up and replace it when it does (it's probably going to run fine for a long time as-is). 4.0's are stout motors, it will run for a long time with lower than "perfect" oil pressure, and if it does go... there are lots of them in wrecking yards to replace it with.

As for potential fixes if it really bothers you that much... the two possibilities that are most likely to be the issue... worn main and rod bearings (very likely) or a worn oil pump (less likely). You could replace either, but you'd probably be better off with a whole engine overhaul to "do it right" when you start looking at replacing rod or main bearings.

Short answer: it depends. What year and how many miles?
 
Needs to be verified with a mechanical gauge as suggested. What brand of oil filter are you using?

Off topic--slightly--but another anecdotal note on OIL FILTER QUALITY. We finished up installing a new timing chain kit in a 1986 Toy p/u 22RE engine. I was gone from the shop and the parts house sent over a Champ filter--I always specify Wix/NapaGold or Hastings--and the tech installed the Champ filter. Well, when the engine was started cold it sounded like a diesel, only on the first start of the day. Swapped out the Champ filter with a NapaGold--problem fixed. Lesson: NEVER USE CRAP FILTERS.
 
Off topic--slightly--but another anecdotal note on OIL FILTER QUALITY. We finished up installing a new timing chain kit in a 1986 Toy p/u 22RE engine. I was gone from the shop and the parts house sent over a Champ filter--I always specify Wix/NapaGold or Hastings--and the tech installed the Champ filter. Well, when the engine was started cold it sounded like a diesel, only on the first start of the day. Swapped out the Champ filter with a NapaGold--problem fixed. Lesson: NEVER USE CRAP FILTERS.

Yep. OCOD=Orange Cans Of Death.
F*R*A*M= Forever*Ruining*Automotive*Motors.

There's more than just crappy Fram filters out there.
 
Off topic--slightly--but another anecdotal note on OIL FILTER QUALITY. We finished up installing a new timing chain kit in a 1986 Toy p/u 22RE engine. I was gone from the shop and the parts house sent over a Champ filter--I always specify Wix/NapaGold or Hastings--and the tech installed the Champ filter. Well, when the engine was started cold it sounded like a diesel, only on the first start of the day. Swapped out the Champ filter with a NapaGold--problem fixed. Lesson: NEVER USE CRAP FILTERS.

I always went to Toyota and bought factory filters for my Toyota. It would only have zero knocking on start up with a factory filter.

Plus, they were only $5 which was nice.
 
So when my jeep is cold oil pressure is great once it warms up it drops and when I stop the gauge drops to zero, what do you think my issue is and how can I fix it?


I fixed mine with a high flow oil pump, new crank bearings, a better dynosaur oil brand oil, and switching to 20W50 oil. That was after fixing other issues, like getting a new OP sensor, and fixing the overheating issues. Mine starts at 50 psig and never drops below 20 psig now. 289,000 miles now.

What year and mileage is yours? What oil brand and spec and filter are you using? Any other problems?

Leaking fuel injector, unburned fuel, running rich, miss firing cylinder, can dilute the oil too and cause issues!!! Check the oil for smell of gasoline! Also exhaust leak blowing on the block can thin the oil!!!! Ask me how I know!!!!:soapbox:
 
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