low oil pressure

diggerules · #1 (**permalink**) 08-26-2008, 12:10 PM

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 · #2 (**permalink**) 08-26-2008, 04:30 PM

Did the manual gauge use a different sending unit?

Sounds like a new oil pump is in order.

diggerules · #3 (**permalink**) 08-26-2008, 09:42 PM

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 · #4 (**permalink**) 08-26-2008, 11:54 PM

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

diggerules · #5 (**permalink**) 08-27-2008, 12:00 PM

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 · #6 (**permalink**) 08-27-2008, 05:14 PM

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 · #7 (**permalink**) 08-28-2008, 02:21 PM

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 · #8 (**permalink**) 09-16-2008, 10:34 PM

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 · #9 (**permalink**) 09-18-2008, 01:48 AM

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 · #10 (**permalink**) 09-19-2008, 04:04 PM

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.