Hey yall! So I recently bought a 2000 Jeep Cherokee. She's got some high miles on her, 247xxx. I've owned Jeeps my whole life (the 4.0 inline 6 and the 3.6 V6). When I picked it up, it ran great. It did seem to have low oil pressure when hot at idle (15 psi maybe ??) When I got it home, I changed the oil (15w - 20, cuz high mileage) and put a new oil filter on it (Wix). Then, the oil pressure went to almost 0 when the engine was at running temp and only while idling.

So, I'm a bit puzzled by this oil pressure issue I'm experiencing.

Problem
Oil pressure is almost 0 when the engine is at running temp and only while idling. When at temp and idling, there is a slight knocking sound from the bottom end. Does not knock until it's warm and goes away when on the throttle.

Tried Solutions

• New oil-sending unit
• Put a machinal gauge on it (Same readings as the dash)

Solutions I'm going to try

• New rear main seal
• New oil pan gasket
• possibly, a new oil pump
• Heavier weight oil like 20W

I'd love some ideas, feedback, whatever yall think my issue could be, and how I could solve it. Thank ya!
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Most with this problem use a 15w-40 oil it will have a better idle oil pressure .

I agree ...I'm using Castrol GTX High Mileage 10w40 in Central Florida.....230000 miles....no low pressure either when cold or hot or at idle or going 60mph...

Welcome to the forum....most use the signature for more information regarding your vehicle...
Hope this helps

15W 20?
Isn't that part of the problem right there?

I'm sorry, I am using 15W40.

Thank you very much, I appreciate the help! Excited to be here!

Mine has low oil pressure at hot idle...9ps...i and has been like this for about 7 years. Has slight knock when cold but no issue after it warms up and I'm running Rotella T6 15w40 . Pretty sure previous owner had the famous crack head issue and drove it for a bit so the bearing are little loose now. The injector wires are numbered and the head and metal gaskets on exhaust looks too brand new when I got it so pretty sure someone has been into it . I'm just gonna keep driving it till something happens.

1) replacing rms and/or pan gasket will do nothing to help oil pressure. Replacing oil pump probably won't help.

2) given the model year and cracked head possibility might want to get coolant in oil analysis.