is oil pressure ok??

[amandazman]

Hi, I have a 96 cherokee 4.0 Hi-output 4 WD with 167000 miles. When I start the Jeep it has about 65-70 psi oil pressure. After driving a bit, the pressure drops to around 50-55 while driving, and 25-35 psi at idle. I just bought this Jeep used and was wondering if this would be the cause of my check engine light to come on as it does. It will be off for a couple of days, then come on for a couple of days. Is there anything I should check before I get into real engine trouble?

[JDPascal]

Minimum oil pressure spec is 13 psi at 600 RPM. Oil pressure should be 37-75 psi above 1600 RPM. Maximum oil pressure is 75 psi

These are the specs from the FSM so looks like your good to go!!!

What oil are you using? 10w30 or 5w30???

JD

[amandazman]

Preciate it. I am using 10-30. This is my second jeep. first was older wihout all the guages. I wasn't sure where I should be, so I appreciate the help.

[cusz28]

Hey, can anyone help me? I've got an 87 cherokee with nooo oil pressure sometimes, very little all other times, and normal pressure about twice a week for about 10 minutes each time. I think its the pump, what do you guys think?

[BARGERUNNER66]

Originally Posted by cusz28

Hey, can anyone help me? I've got an 87 cherokee with nooo oil pressure sometimes, very little all other times, and normal pressure about twice a week for about 10 minutes each time. I think its the pump, what do you guys think?

I HAVE THE SAME PROBLEM WITH MY 1987 JEEP CHEERK...I AM GOING TO CHANGE THE OIL PUMP IN THE MORNING...I WILL LET YOU KNOW IF THAT WORKS'........
BARGERUNNER66

[JDPascal]

Quote: <HR SIZE=1>Originally Posted by cusz28
Hey, can anyone help me? I've got an 87 cherokee with nooo oil pressure sometimes, very little all other times, and normal pressure about twice a week for about 10 minutes each time. I think its the pump, what do you guys think? <HR SIZE=1>

Originally Posted by BARGERUNNER66

I HAVE THE SAME PROBLEM WITH MY 1987 JEEP CHEERK...I AM GOING TO CHANGE THE OIL PUMP IN THE MORNING...I WILL LET YOU KNOW IF THAT WORKS'........
BARGERUNNER66

I seriously doubt that your problem is in the actual pump. More likely the regulating valve that is in the pump housing. Can stick intermittently. I've had good success with using an engine flush to remove the deposits and have obtained a steady pressure that way.

Could also be a plugged pickup screen. Deposits block flow to pump gears and can be intermittent too. If the flush doesn't help, removing the pan will show this right away.

Others have had success with replacing the pressure sender and/or fixing the connector contact to the wiring harness.

Both easier and less expensive than replacing the pump.

JD

[rksnc]

I would question bearing clearance first. The bearings is what makes the oilpressure. Oil pressure comes from how much pressure it takes to send oil down it's ways. When bearing wears the oil pressure will always drop. The more the wear the more the drop. The pressure may increase at higher rpms only because now you are trying to send more oil. If i was going to drop pan to change pump I think I would go ahead and do the bearings. You will thank youself for doing so.

[JDPascal]

I forgot to include the "always do first thing".

Alway check your actual oil pressure with a mechanical gauge - under normal operating conditions - before going ahead with any work to "fix oil pressure". "You will thank youself for doing so", too.

JD

[sklater]

Hey, I have had the same problem with my 98 cherokee. I was told by some guys at the Jiffy Lube where I wash windows (a very lucrative college job ) Anyways, what happens is when I start it up oil pressure is right on, but as it idles the needle drops. But if I start driving the oil pressure climbs back to normal. One guy told me that it was the fuel pump probably. But the manager of the store told me that it was some sort of ring found where the oil pumps through, and it is much cheaper than the pump and easier to fix. Can't remember exactly what he said. Will ask him again tomorrow at work.

[rksnc]

Good Luck on that one. That story told to you won't hold any water. But coming from Jiffy Lube,,,,,?

[sklater]

Okay, i mis heard him. He was talking about some rings found on the pistons. Sometimes one of the rings will go bad which will give off a bad pressure. Also it might be the pump, or many other items. Dont want to figure it out though.

[cusz28]

I'm new at the whole jeep thing. but I have been around (and IN engines) enough to know that it isn't a bad oil controll ring or just normal driving, nothing personal sklater, but I will never go to Jiffy because they like screwing stuff up. be glad it's only a collage job... as with the mechanical gauge, it's a good idea, if i had one. as with bearing clearance, my engine can't remember the time when it had .002 clearence on it, it has 234,000 miles. what I'm in dilemma with is the fact that it sometimes jumps to around 40, then drops to zero, then stays at 15 for a long time, then drops to zero. and so forth, but 40 psi comes few and far between, thats what I'm worried about. the engine flush is a good idea, I need a change anyway. Well, if you guys could help me out by throwing some omre ideas around, that would be great. again, I'm no novice at all about engine building, i just don't really deal with 4.0 straight sixes. more like 350's or 400's for me. I know that sixes have a tendency to be a real bitch, so the more ideas the better. ~thx

[AlohaBra]

Originally Posted by amandazman

Hi, I have a 96 cherokee 4.0 Hi-output 4 WD with 167000 miles. When I start the Jeep it has about 65-70 psi oil pressure. After driving a bit, the pressure drops to around 50-55 while driving, and 25-35 psi at idle. I just bought this Jeep used and was wondering if this would be the cause of my check engine light to come on as it does. It will be off for a couple of days, then come on for a couple of days. Is there anything I should check before I get into real engine trouble?

I have had this problem on my 97 Cherokee 4.0L for the last 50k miles on and off. Jeep now has 123K on it, and it has always been the sender.
First change the oil and filter to make sure the oil filter check valve is not stuck open, then change the sender which is easy to get to. You will see at the parts store that Chrysler changed the sender design later.
The weather pack connector on these Jeep gives many electrical problems.

[AlohaBra]

Originally Posted by amandazman

Hi, I have a 96 cherokee 4.0 Hi-output 4 WD with 167000 miles. When I start the Jeep it has about 65-70 psi oil pressure. After driving a bit, the pressure drops to around 50-55 while driving, and 25-35 psi at idle. I just bought this Jeep used and was wondering if this would be the cause of my check engine light to come on as it does. It will be off for a couple of days, then come on for a couple of days. Is there anything I should check before I get into real engine trouble?

On your erractic check engine lite, it could be anything but most likely the NSS switch which can be rebuilt. Pull the code. Many people posting has had this problem.

[kmerian]

My problem is similar, lately when I have to stop quickly, the oil pressure drops very low and then recovers quickly, I have also noticed that if the engine starts to get too hot, my oil pressure will also drop. I have an 89 I-6 unfortunately I only have the dummy lights so I cant give exact readings.