Hey all, first major problem I'm seeing on it's way with my 94 Cherokee Country with 247,433 original miles on the engine. After my last oil change, (Could be coincidence) I've started noticing a noise that sounds very much like the "grinding/whirring" that a power steering pump makes when it goes bad, but it's coming from the motor. (or trans, hell, I don't know. sometimes the "whirring" will go up and down in pitch like my engine's rpms and will change pitch when it downshifts as well, so it's related to either engine or trans. ) Related to the trans, I just changed my transmission filter as well and drained that fluid because it began slipping out of gear at stops maybe once a week. Trans fluid looked beautiful, nice and red, no metal shavings in the pan. Back to engine. Erratic oil pressure. It's around where it usually is, 35-50 depending if I'm on the skinny, but when it idles the needle will hop around within 5 or 10 psi on the gauge of where it actually is. I've terrified myself thinking of my engine blowing or something or the trans dying on me. Anyone have these symptoms, or suggestions for me? Totally lost. Never had anything this magnitude.

 

The whirring sound could possibly be the transmission pump itself going out. With a vehicle with that many miles on it, I probably wouldnt have changed that transmission fluid. Ive never had any luck changing transmission fluid in a slipping transmission. Usually the new fluid will make it worse and usually the transmission will fail.

 

My step father thought it would be the trans pump as well. Which if that goes bad can burn the trans out. Thanks for reading through and replying man, appreciate it. I just dropped the trans pan and changed the filter, I didn't flush it out or anything. And it shifts a lot smoother and hasn't slipped since. How do I replace a trans pump? Where the hell is a trans pump?

 

When a noise changes pitch with the rpm of the engine, it's most often something pulley driven. With all of the noise of the engine, it's hard to tell exactly where the noise is coming from. If you don't have, or have access to, a mechanic's stethoscope, use a piece of thin pipe like a length of 1/2" water pipe or anything else that you can find laying around. Start the motor and put one end of the pipe to your ear. Carefully (watch the belt, pulleys, and fan. They have a tendancy to bite) put the other end, making actual contact, to each pulley driven component and see where the noise is coming from. What I mean is to make contact with the body of the part like alternator, ps pump, etc. This old school method often works to help pinpoint the offending part. The only one that will be difficult to get to is the idler.

As to the oil pressure, I had a recent similar issue with my '98. The pressure went way too low on idle and fluctuated too much. To know for sure without throwing parts at it, you'll need to use an diagnostic oil pressure gauge substituting it at the oil pressure sender location which on the 4.0 is right below the distributor. My issue was the oil pressure sender. Replaced it and the readings went back to normal.

The trans pump is internal.

 

****. So, new transmission time? or can I rebuild the trans and just change the pump? or not worth the work if I could just throw a new trans in?

 

bump

 

As for the noise change with RPM, keep it simple. Take the serpentine belt off. Then run the motor, if the noise goes away, you know it may be an accessory.

As far as the oil pressure, I agree, a manual oil pressure tester is going to be the only real way. Its easy as heck. The hardest part will be locating a kit with the correct adapter for the Jeep. Its just a manual gauge that goes into the port your oil pressure sending switch usually sits.

The oil pressure sending switches do go bad and are common, but with your mileage I'd test the theory and make sure everything is actually up to snuff with the oiling system before just throwing parts at it. A pressure test is your best route.

As for the transmission, raise the Jeep up and put jackstands all the way around SAFELY under. Put it in gear and see if you can hear the whine through the gearset, and if it is coming from the trans area. If at the end of the day you do need a transmission, the AW4 auto is very plentiful and rather simple.

 

I've been pretty upset about this all day knowing I might have to swap a trans that I have never done before and that I'm about to lose a lot of money. But, it just occurred to me, if this one blows up, I can do a 5-speed swap. Unless those are impossible.

 

Unfortunatley I am also familar with this sound. Sorry dude, but it's the tranny or torque converter. I have had both make this type of noise and either one can cause the tranny to slip. If the noise changes pitch and sounds like a turbine whine, it's the torque convertor. A grinding sound would be the pump. Either way, not a fun time....

 

My 70 Gto has a bad torque converter and it sounds like a super charger !

 

5 speed swap isnt worth it, your better off buying a 5 speed imo. You can replace the aw4 for like 100 bucks where I am off of craigslist. An ax15 never sell for less then 450 here in the portland area

 

****. It's the whirring sound that is just like the RPMs from the engine. Sounds like a turbo. Whiiiirrrrrrrr, (shift) whiirrrr.... I'm in for then. ****. Thanks guys. What a bummer.

 

Busted's idea of taking the serp belt off is a good one,just to expand dont dilly dally if this is done as you will not have water circulating. As stated an auto to manual swap is possible but looking at the time/money aspect you'd be better off to put an AW4 back in.