low oil pressure

[diggerules]

Hello all. I am new to the thread. i have researched a lot of old postings and I am at a stand still.

I have a 2000 cheeroke sport 4.0L. Start Cold the oil gage is fine. after heating up the pressure drops. at idle or costing (low rpms) the check gage light comes on and the gage dropps out completely.

last night i put a manual gage on. Same thing is happening with the manual gage.

it has only 84000 miles on it. I am actaullly in the process of selling it. Just trying to figure out if it is something I can fix prior to selling.

I am at a stand still. where does this leave me now? What can I check next? could this be the oilpump or the engine itself?


Thanks for your help
Greg

 

[Bounty__Hunter]

Did the manual gauge use a different sending unit?

Sounds like a new oil pump is in order.

 

[diggerules]

Well, i had to unscrew the sending unit, and screw in the manual gage fitting. Then ran the tube from the fitting I just put in place of the sending unit to the gage it self.

I have never done his before. I think I did it correctly but It wouldn't the first time I was wrong (Esp if you ask my wife, haha).

P.s. You still in the Army or Prior Service? I hit 8 Years next month. Hooah!

Greg:???:

 

[Bounty__Hunter]

2.5yrs active duty 11B/88M, 4yrs National Guard 11B. '90-'97.

 

[diggerules]

I was 31U for the first 4 years been 25S since then. Currently stationed as a recruiter right now.


Any idea on how much is involved with changing the oil pump in the inline 6 4.0L engine. I have never tackled that before. Just deciding if this is something I can do or take it somewhere.

Thanks

Greg

 

[Bounty__Hunter]

Shouldn't be too bad, drop the oil pan and change it out. May or may not need a new pan gasket.

Now there may be other causes to low oil pressure, maybe somebody with more engine experience will chime in. I'll check my FSM in the meantime.

 

[Sly8795]

I don't know if a 1990 has a different sending unit but I had the exact same problem. However at warm my guage never went to 0 pressure though but once it warmed up it wouldn't go above 20lbs pressure. i got nervous but replaced the sending unit first no problems since.

You did mention a second gauge you hooked up and the same thing happened so maybe it is something else but thats what happened to me.

 

[dbxtr3]

change the sending unit. If no change in oil pressure then change the oil pump. It not hard to change you just need a new oil pump and oil pan gasket.

 

[97teejay]

My 1997 Tj with a 4.0 does the same thing, oil pressure is great but when you get on the trails creeping or hit a steep hill too slow at really low RPM the oil pressure can drop and trigger the "check gauges" alarm. It bounces right back up really fast so it's never concerned me. Should i be? I just figured it was a Jeep thing...

I'm running 5W-30 Amsoil, 140K

Is dropping the oil pan pretty simple on Jeeps? most motors you have pull the axle or lift the motor out to remove the oil pan.

cheers!

 

[dbxtr3]

I got 4" of lift so that is 4 more inches of clearance between the oil pan and my front axle so I plenty of room for me. I think if you jack up a stock height jeep by the body and disconnect the front shocks to get a few more inches of front axle sag you can get the oil pan off. Some say moving the trans lines and removing the starter make it easier.

My 89 XJ 207,oo mile has 40psi of oil prssure at start up when cold cruiseing down the hwy. it has 25-30psi and at an idle hot it is around 3-5psi. I am not taking any chances I am going to replace my oil pump.

 

[diggerules]

OK so it has taken me a while to finally get around to this. The jeep really has not been driven much since the problem.

I have never removed the pan before it was a pain in the ass. Yes had to jack up the engine in order to get the clearance.


Only problem is after all this work putting in a new oil pump. I still have the idle issue. I was so frustrated I quit today. I am going to hook up the manual gage again to verify that the sending unit is not jacked up as well.


I would think if there really is an oil pressure problem that it would start to overheat and you would hear noises/knocking. It runs smooth. I am completely stumped any imput would be appreciated.

 

[HiHood]

Sounds like a slug problem, pull the pan again and clear all lines, screens and gaskets, seals you can see. Do the flush thing and put it back together, changing the oil about once every 500 miles for about 4 or 5 times.

 

[alleydog]

If you have good oil pressure when the engine is cold and it drops off when warm, I think your engine is getting worn to the point that the pressure is getting lost through all the loose bearings. If the engine doesn't rattle or tick, You might be able to replace the oil pump with a hi volume pump. Melling makes one for the 4.0. Caarquest sells it for a little over $100.

 

[diggerules]

That's what I did use. Autozone for like 78. The exact same symptons as before though

 

[54cj3b]

had that prob in a 76 dj5 no oil pressure at low idle 258 I6 eng

my remedy was this I added a qt of diesel fuel to the old oil ran eng about 15 min than turned it off drained oil but left filter refilled 20/50 ran it about 30 min shut it down drained oil again changed out filter refilled with 10/40 now I have great oil presure eng just had major sludge build up and the diesel fuel flushed it out
no more low oil presure issues since learned this trick from my grandfather over 30 years ago . sounds crazy but it works ...also improved the emmissions issue I was having ,, passes everytime now with flying colors

 

[carnuck]

Sounds like the filter is probably orange colored and it suffered internal damage (collapsed) or something is in the oil pan and plugging off the screen.

 

[xjmarc]

Had the same problem and ended up being cam bearings. Not exactly an easy fix.