I have a 2001 cherokee Sport with the 4.0l motor. After driving the vehicle and getting it to operating temperature at Idle the OP gauge on the dash will drop all the way to 0. Most common issue is known to be the sending unit so that was the first to be replaced. After issue was still presenting it self I hooked a mechanical gauge up just to make sure I wasn't sent a faulty unit. Running vehicle at 3k rpms in park the gauge spikes to about 50psi. Slowly during the 3 mins I held it there the oil pressure dropped all the way down to almost 0. Next to be replaced was the main bearings, rod bearings, and oil pump & screen. Again hooking a different mechanical gauge just to double check I was not using a faulty piece of equipment the problem still presents it self. Short of having the engine rebuilt is there any suggestions on what to do next?

Thanks in advance, Cstech

 

Mine is doing something similar. While you are driving is it maintaining about 40-50 psi? Does it drop off at all while you are staying a steady rpm?

 

Did you try clesning out the passage that delivers the oil to the sender unit? Lots of good information about this problem in this previous post:

https://www.cherokeeforum.com/f2/low...resure-169907/

 

Are you running a Fram filter?

 

Was the oiler for the timing cover reinstalled when the mains were done?

Could be a wiped out cam bearing.

 

The model year says it all. Common problem, mine has had the same low pressure readings for years. I stopped worrying long ago. You changed everything but the cam bearings so that may be the cause. HOWEVER there have been complete rebuilds by ATK and Titan that ended up with low pressure right from the start. I say "if it ain't knocking,keep rock'in".

 

dump some sea foam in the engine drive around for a 100 miles or so and dump the oil. the sea foam will get in places and clean stuff out. i did this and so much stuff came out and now i run rotella 15w-40 its the white bottle stuff, and a lukas oil stabiliser and everything runs like a champ. if that dont fix it then u got bigger issues my friend.

 

So how much coolant have you lost?

 

The only thing Lucas Oil Stabilizer fixes is an excess of cash in your wallet...

A 0331 with no oil pressure at idle is a bit past Seafoam remidies. Lol