scott7689

Ive got a problem with maintaining oil pressure once my cherokee gets warm. It has the 4.0. It will hold pressure fine at speed. if I come to a stop once the jeep has warmed up my oil dummy light starts to come on unless i keep the RPMs up. I have already swapped to a heavier weight oil to try and keep it from thinning when hot. Im just lookin for some help before I spend money on parts I may not need.

salad

What oil filter are you using?

Have tou tried verifying pressure with a mechanical gauge? Should be able to rent one or get access at a parts store. The sending units have been known to crap out and give strange readings.

scott7689

Im running a fram filter. Havent checked it with a mechanical gauge. This all just happened yesterday and of course we were 15 milesinto the woods at Coal Creek ORV.

RTorrez1

Get rid of the fram filter first of all the verify the pressure with a mechanical gauge. you can borrow one from any auto parts store like autozone advanced.

cruiser54

Just ditch the Fram for a Wix or Napa Gold and report back.

scott7689

swapped to a wix filter. seemed to help a bit but its still giving me the same problem when it is in gear at a light. if i throw it to nuetral it wont throw the oil light. but with a load on the motor at idle it does

cruiser54

Try this:
http://www.jeepforum.com/forum/f19/4...fixed-1304679/

bigbadon

What year and how many miles? Sounds like the classic case of engine wear. Is it knocking? Mine has done the same thing for awhile but runs like new. I would just drive it but listen out for noises, when it starts to knock then it is time to do something.
Low oil pressure won't kill an engine as long as the pump is giving flow and the pressure increases above idle.....low pressure is the result of wear,not the cause of it!
When the clearances become critical you WILL hear it.

tjwalker

Always post year and engine.

As RTorrez1 mentioned, verify it with a mechanical gauge.

Good data = good decisions.

Could be a sending unit (buy it from Jeep), could be an actual clearance issue within bearings, oil pump, etc.

Newbie101

I had the same problem, seemed to be the oil pressure sending unit was faulty, i went and twisted it a bit back and forth and fixed it. But also was told that replacing it would help. Go get it checked to make sure the pressures good, then if it is replace that unit.

scott7689

The year model is an 89. What really sucks is the motor only has about 3500 miles since a rebuild to fix thrush bearings that could be heard upon cranking. now it is doing the same thing. im just trying to get as many miles as I can before I end up having to rebuild again.

tjwalker

Don't get ahead of yourself. Get the verification you need with a mechanical gauge. Can be rented inexpensively from many parts stores. Then you'll know.

bigbadon

Are you referring to the the THRUST bearing on the crankshaft main journal? If so this may be the problem are to investigate....they may have put in the wrong size bearing. It is common for the factory to use oversized bearings and if your thrust bearing was replaced with a standard size your oil pressure would drop.

1991Jeep_Man

I'm just going to skip all the responses so far and say the magic word:

SEARCH.

I promise you'll find every solution to every possible oil problem you are/might be having/could possible have.