upholserybarn

Just bought a 2001 jeep cherokee, knew it had afew engine problems, now we're trying to figure them out. NEED HELP. New head was put on, new oil pump,and bearings 3 weeks ago before we bought it. Ran fine the first 2 days, but alittle rough idle at stop lights. looked at it when we got home, checked hose connections everything seemed ok. old owner said mechanic told him it could use cam bearings . The next time we got in it it idled and ran so rough we could barely make it a mile and back home. Now the oil filter/pump is making a hissing sound that gets louder with rpms. Shows oil pressure at about 10 idleing, but old owner said that has been showing for years. Head was cracked thats why he had it replaced. We planned on replacing the cam bearings because maybe that was the pressure problem. But now the extremly rogh idle and running is the major problem. Temp is running about 210 but that seems to be normal here in your forum, although my husband says thats kinda high, worried about cracking the head again. Any suggestions or opinions?HELP!!!

ken72

210 is perfect for this engine. Only worry if it reaches above 210 and the fan does not kick on to cool it off. As far as your Idle is concerned I would check the throttle body sensors. Start with the TPS. i just dealt with some bad idle issues and my TPS was faulty. Oil pressure is low even at idle. It should be around 15 or 20 at the lowest. You could be dealing with a faulty oil pressure sender and your idle issues could have nothing to do with it. Check your throttle body and sensors first and maybe even your coil pack.

4X4XJ

I've got a 2001 XJ Limited... When I bought mine I noticed it had a valve gasket problem and was leaking oil everywhere down the left side of the engine. You may want to look for this as well. Also, change all of the spark plugs and coils (it uses the rail ignition setup instead of wires). Hope this helps!

upholserybarn

Any idea what the hissing/buzzing sound coming from the oil pump/filter might be? We're thinking maybe cam position senser wasn't aligned right .Apperantly last mechanic disabled check engine light cause it doesn't even come on a start up. Going to get loaner scan tool and pull codes to see what it shows unless they cleared it after repair.

ken72

Getting a scan tool on it is a good start. A rough and unstable idle is often caused by an issue in the throttle body ie TPS, IAC or MAP sensor or a fuel issue like a bad injector. The oil pump is inside the pan so I doubt you are hearing any hissing from there. The only thing in the area of the filter is the starter and the a/c compressor above it along with some other vac points. Take a look inside the bumper and look for a round black rubber/plastic ball. It is your vacuum ball. Make sure all the hoses are still connected. The problem is even though the head on these are a week point they do not often crack unless they are over heated. That heat can cause a lot of other damage down the road. I think you need to get a scan tool on it and see if any codes are being thrown. If not then get it to a trusted shop and have them test all the sensors and even the compression. I hope it all works out for you and please post your findings for others to learn from.

tjwalker

The wildcard here is that it had a cracked head. That means that coolant mixed with oil and very possibly damaged your bearings.

You may have more internal damage than was originally estimated. Not unusual with a cracked 0331 head, damn Jeep for this dog head!

I would verify your oil pressure with a MECHANICAL oil pressure gauge. You can rent them from many big box parts stores.

Spec. for the 4.0 is as follows:

*Not less than 13 psi at HOT idle
*Between 37-75 psi over 1600 rpms

upholserybarn

Got my terminology wrong, buzzing sound is coming from oil pump drive assembly, but the point is mute now. Hubby drained the oil last night , it was so thick it must be straight 50. So engine is coming out and hes rebuilding it. hope the top end didnt get damaged much as it was just redone 3 weeks ago. But when its finally done, we'll enjoy our Jeep!!!

DaddyCat

PO (previous owner) and their "mechanic" should be nutered, I despise dishonest people. I'm sorry you had these problems but when the jeep is healthy you will have a very cool vehicle.

dln2001

I have the same low oil pressure and was wondering if you found the root of your problem, I'm thinking my cam bearings may be shot

94JeepCherokeeMan

Good luck

mayeday

have a 2001 jeep cherokee classic. engine gave ou while driving and it would turn but not crank. did a compression check and determined engine was bad. replaced enginge, radiator, power sterring pump, water pump and all electrics...car engine will turn but not fully crank. fuel pump is working and battery is new. starter works, new transmission. any ideas on what would keep the engine from running?

Evilpopcorn

... Battery?

salad

Excellent idea. I agree with tjwalker. Normally there can be a lot going on but it sounds like the engine wasn't actually fixed. 10 PSI "for a while" and only replacing the head this month doesn't bode well at all. The oil pump is driven by the cam shaft by the way.

mayeday

replaced the engine in my 2001 jeep cherokee classic, but engine o=wont crank. it is spinning but the engine isnt getting any fire to the coil pack. ive changed the radiator, all electricals, cam shaft positioning censor. any suggetions..??

salad

Do you have fuel?