So my 2001 jeep xj with 130k miles has had low oil pressure at idle since I bought it a few years ago. I thought it was the sending unit and it wasn't so I got screwed a little but it wasn't knocking or making weird noises so I replaced the oil pump with a new high flow oil pump and the oil pressure stayed around 10-15 hot idle (i know its not great but shes too rusty for it to be worth an engine rebuild) the oil pressure went up to above 20 - 25 while driving. I didn't drive it much over the winter and now all of a sudden the oil pressure doesn't go above 15 psi no matter what the rpm. hot idle is about 10 psi and at 3000 rpm is 15 psi. It started making weird noises when starting in the winter but I believe it's because I have thick oil in it for the summer and it just took a minute for the oil to reach the pump because after a few seconds the noises went away. I checked it with a manual gauge and it reads the same. I'm wondering if there could be a block in the oil system or maybe my oil filter could be bad. Any help is appreciated.

 

What brand oil filter?

does the oil on the dipstick or under the valve cover look like a chocolate milkshake?

 

Wiring on sensor might be intermittent too

 

i have a wix oil filter in it and it’s only about 2000 miles old if that. The oil is about as old as the filter and isn’t milky. I had a cracked head a while back but replaced it. I’m sure that’s why my oil pressure is low to start with but it’s odd that after I don’t drive it for half a year that all of a sudden the psi won’t go over 15. When I replaced the oil pump the oil pan was caked in gunk. I cleaned it but maybe there was some old oil deposits that could have clogged the new filter or something?

 

we’ll I checked it with a Manuel gauge and it is the same result as with the sending unit.

 

confirmed low pressure... assuming oil level is correct, next step is pull pan to inspect oil pick up tube, no more engine running, else you may do more damage, like throw a rod, score pistons, etc...

 

yeah, the only problem is this car is my only ride to school and work. Also, I just replaced the oil pump and oil pickup tube barely 2k miles ago. Im hoping it's just some gunk clogging the filter or something because it's weird that before I put the jeep away for the winter the oil pressure would go up to 30 psi driving and now after barely driving it, it doesn't go above 15... I really don't have the time to work on it let alone rebuild it until summer.

 

Why was pump replaced? Same low pressure problem? after pump replacement was pressure ok before it got bad?
consider maybe that the new pump has become loose, pick up tube loose, gasket installed wonky? If so that WILL cause low pressure. How about drain oil, drop the pan, and inspect pump and pick up mounting, inspect the gasket, (remove the pump to do this, make sure that the pump and pick up have not gotten loose, maybe one of the bolts backed out or gasket got pinched or torn?
I hope that is the case, as that should be an easy fix, new gasket, use locktite, or lock washers on pump bolts.

That is next thing to do, check that pump I think.

But why was pump replaced, when did low pressure start?

I repeat, do NOT run vehicle, if you do, give the low pressure, you may end up with an unrebuildable engine, in which case you will need to work even more to afford the repair. keep running with low pressure and the engine may hand grenade, throw a rod through the block, seize a valve, broken bits, carnage, very expensive carnage.

so why was pump replaced? But golly if the low pressure occured after pump replacement, then Id for sure suspect pump install has gone bad.

with pan removed you can also see manythings, wiggle the rods, note excessive play, see wear on cam etc...

 

Another possibility is the. new "Chinese Replacement Auto Parts" pump itself.....stuck pressure relief valve etc etc.

 

we’ll I used a melling oil pump so I assumed it was ok. But good news! I replaced the oil filter and the oil psi jumps up to 30-40 again while driving. Hot Idle is still around 10-15 psi but I’m ok with that as long as the pressure goes up to 30 above 1600- 2000 rpm. When I replaced the oil pump there was gunk all over so I assume what happened is that my newer oil collected all the gunk and either slowly clogged the filter or it sat at the bottom of the pan and when I started it for the first time in a while clogged the filter up.

 

Nice job!! Keep us updated.

 

id be inclined to repeat pil change soon, so as to assure all that oil pressure robbing gunk is totally removed. clogged filter? Does the filter not have a bypass valve?

Beware, so filters cross referanced to "fit" may not have the correct bypass valve, antidrain back valve and such, but still "fit".

 

Old school rule of thumb; 10 psi for each 1000rpm. Your okay. Might consider going to straight 30wt oil. No additives.

 

1085 Wix oil filter.
I would add 1 quart of Marvel Mystery Oil as it dissolves the gunk nicely.
After 1000 miles, change oil and filter.