Hey all, sorry for the novel, grab some coffee! This is going to be educational for someone, hopefully me.

Back story on my 96 Cherokee with 4.0, AW4, NP242 with 175,000 miles.

7-8 years and 10-15k miles ago I had a smoke of cloud behind me, which I determined to be a blown front pump seal in the trans. Dropped it, replaced the seal and moved on. Sold the jeep, bought the jeep back, and now having what I think is trans issues.

Before I get into what it is doing, here is the list of the things I have done/tested/replaced/tried, please read the list before suggesting these things, to save us all time, please and thanks!

Replaced:

• Rear driveshaft u-joints with spicers
• Tcase fluid, looked good, no metal
• Entire ignition system, including the distributor
• 2 different TPS sensors
• Entire suspension, front and rear, did long arms, and new leafs. Not a single old bushing anywhere
• Trans mount
• Entire cooling system, jeep runs so nice and cool
• Entire trans cooling system, trans lines and new disconnect fittings, I do not have accessory cooler, but do have a new radiator.
• Upstream O2 sensor (NTK)

Tested:

• Trans solenoids - all ohmed in spec at 12.6
• CKS, ohmed like it should
• Flex plate is not cracked and TC bolts are tight
• Charging - 13.9 volts with AC blasting.
• Static battery voltage - 12.8

Tried:

• Removing transfer case linkage to ensure 2wd is engaged fully (tcase drop, I know, bad)
• Adjusting TV cable at just about every position
• Running without TPS disconnected (don't do that, didn't even get 100ft, experience what felt like massive slippage)

Things I know are bad:

• Driver's motor mount
• Possibly passenger motor mount

What I am experiencing:
I was fully loaded, roof top tent, full of gear, 2 passengers, dog, spare tire. Cruising the north shore of MN on 61, up and down hills, nice cool morning about 9am, jeep was running beautifully, had been running about 60 miles at 55-60mph. Engine temp was perfect 190-200 on the gauge, outside air temp was 70dF. Cruising at 55 with no cruise control up a hill and all of a sudden I hear this little rotational chirping noise coming from behind the dash as engine load increased and then all of a sudden a little instantaneous studder that you could feel in the seat, I eased off the pedal and then got back into it and same thing, chirping and then studder, the studder got more frequent as we went for the next 1/2 mile.

Finally I pulled over onto a side road which was a huge hill up away from lake superior, I was able to find flat ground, I checked the trans fluid and it looked good, smelled good, might have been 0.1-0.2qts high on the stick when checked in park. I got under it, disconnected transfer case linkage to ensure 2wd and then proceeded up this massive hill in 1st and 2nd gear at 2000-2500rpm, chirping sound, BANG!! Huge bang, rattled the whole jeep and startled me. Pulled over, collected my thoughts, let the jeep cool for 20 minutes and then moved on, tried manually shifting, same thing, uphill 1st and 2nd, high engine load, BANG!! Turned around, went home, had to be reallllyyyy easy on the pedal to not have too much load so it would not studder or bang again. At the crest of a hill when letting off the gas just before you start going down hill when the jeep drops in RPM sometimes I would get a little studder/clank.

I also have been experiencing a shutter in reverse since I have purchased this jeep back. The only mechanical thing that could be at this point is the transmission or the blown drivers motor mount, I was hoping the new u-joints would have solved that, but no.

Since this happed, I did all of the above work, minus the suspension work. I took the jeep out again last night for a 15 mile test drive on flat ground and hills, and got the same symptoms and results. I left the front DS out to eliminate the DS and front axle variables. This is when I tried multiple TPS, multiple TV cable adjustments, manually shifting, no TPS connected, etc. Nothing would get rid of the studder and bang. The rotational chirping was gone though, WIN!!! I parked the jeep and left it running and got out, crawled underneath and started listening around, from the bellhousing of the transmission I could clearly hear a whining sound, in drive under some throttle, that whining changed pitch and got a bit louder.

What I think:

• The rotational chirping sound was coming from the distributor under high load. There was an insane amount of side to side play in the shaft, and the bushings were quite brown and warn,
• The transmission front pump is taking a dump and it's time for a new one.

Where I am stuck: This is where I need decision making help!!!

• There is still a slight possibility that the bang is coming from the planetary gears in the transfer case, but I think this is unlikely because I get a little studder/lurch sometimes on decel, and the fluid was clean.
  • Do I leave the transfer case well enough alone for now? A lot easier to replace than the trans.
• Do I fluid flush the trans to see if my problem goes away? This is time and money too.
• Do I replace the transmission?
• Do I replace the transmission AND the torque converter?

 

Wow. I just read all that and it makes me wish you had it all on video. I feel like what I am imagining as I read is probably not what happened in reality lol. Can't wait to hear what people think is going on.

Even after you replaced the distributor there was still side play?

 

After I replaced the distributor the side play went away and was nice and tight, also no more chirping sounds!

 

I don't see that you have dropped the transmission pan and looked for trash in it. This would be the best way to evaluate its health at this stage.

 

I 2nd the above comment ^^^.

Please describe the "bang". Does sound like a baseball bat just hit the floor board? A video or sound clip would be good. A video would be best. The "studder"- do the rpms change when this happens? Need more info.

 

It happens so fast that I am not looking at the tach, but yes it sounds like the driveshaft is smacking the floor.

Update:

Bought a low mileage trans from the junkyard and a new torque converter, got that installed tonight and the issue persists. Though my horrible vibration in reverse is gone. So that is a win. I did drop the pan, do a filter, and swapped the old solenoids into the new trans because the wiring harness was different.

The only difference now is that I am experiencing an intermittent rough idle. Hoping it relates to my problem. I don’t know.

Going to be cleaning the throttle body, throwing some fuel injector cleaner in and testing fuel pressure. Probably should have done that long ago.

 

I found some weird binding in the transfer case.

see video here:
ehat are your guys thoughts on this?

 

It makes sense to me that when the t case was out of the vehicle that it would have been a good time to split the t case and see how it looks inside. At least that's what I would have done and what I would have suggested you do. Now it looks like you need to remove the t case, split it and figure out what's wrong with it or replace it with a junkyard one.

The bang you are describing is obviously a gear or chain skipping a tooth. Any component in the driveline with that issue is going to be grinding up metal and that will show up in the pan and in the lubricant. The suspect parts based on your detailed description are the transmission, t case and rear axle. Since your posted question was wheather to replace the transmission that was what I and others focused on.

What did you find in the bottom of the original transmission? I suspect that there was some clutch material and some metal flakes. That would be consistent with the failing reverse symptoms. You were probably going to need to replace it anyways, but if it was the cause of the bang then I would have expected to see large chunks of steel or aluminum in the pan.

Since you still have the original issue you should remove the rear differential cover and inspect the gears in there as well.

 

the fluid wasn’t bad, I would say a little dark, but no chunks, and I took the pan completely off and it all looked fine in there.

as far as the t case goes, that’s an easy 6 nuts to
drop it out. That fluid also was very clean when I dumped it, but mind you this bang happened a total of 2-3 times before I started investigating so there hasn’t been much of a chance for failure.

the rear axle was just serviced about 700 miles ago, and everything was in nice condition in there.

I am leaning heavily towards tcase at this point based on your opinion and my own opinions

 

the range fork pads are completely off of the fork itself. I do believe my loud bang sound was due to the range gear slightly engaging an adjacent gear causing the loud bang.