binding and grinding under load

I just swapped out the whole powertrain on my beater, and the replacement junk is feeling pretty bad. For reference, I have a '91, and just replaced the 4.0 engine, the AW4 tranny, and also switched the 231 for a 242 for good measure.

I got everything bolted up today, and when I took it for it's first test drive the thing is binding and grinding whenever it is under load while moving. Revving the engine at stand still is great. Coasting down the road is great. But when accelerating, it sounds and feels like the whole thing is going to crunch up and grenade. It sounds like the engine fan is buzzing into the radiator (it's not), and it feels like the bottom of the jeep is trying to squeeze out a dry turd. It is extremely bad when turning while accelerating (nothing when turning and coasting though).

From my deduction, the engine is okay since the problem does not exist when revving at standstill. Also, if it does not do it while coasting, then that eliminates everything that is synchronized with the wheels (hubs are always locked, rear shaft always turns, rear output on 242 always turns, output shaft on tranny turns, etc), since if it was something there the noise and feeling would be there whenever wheels turned.

I spent a while fine-tuning the 242 shifter, and it goes into and out of all the gears alright (I can tell the difference between 4PT, 4FT, and 2WD), and it does not seem to matter which gear is selected. From my understanding the chain is not spinning when it's in 2WD so I don't think that is the case, but I may be wrong about that. It kind of feels like a slipping chain but I don't know what that feels like.

It also kind of feels like the torque is twisting the powertrain, which is causing something to bind up, which may explain why it's worse while turning.

Anybody got a clue for me?

Could a torque convertor not fully seated and pressing the flexplate towards the engine block cause such a symptom? Probably have issues in all cases instead of just accell. Eric, did the bellhousing push in easily or did you need to pull it with the hardware?

Hate to say it but it sounds like a transfer case issue. Possibly the planetaries? Although that transfer never showed any issues while i owned it... pulled from a running rig and straight to garage and to you. I would swap in your 231 and see if the issue is eliminated. If it's the case i'll refund your money Eric.

It's not the transfers chain Eric, that's got very little slop. And it felt smooth rotating the internals. Checked it again when i threw it in the XJ to meet ya. Thats the reason i bought that particular 242.

Isn't the transfer case always under load? I mean there's no differential between the front and rear shaft in 2WD right, so if the output shaft is turning then so is the input shaft? That kind of eliminates the transfer case right there, since the problem only appears when the jeep is under load in motion--if it was the transfer case then it would always make noise since it is always under load.

Nevermind! :roflmao:

I had a new downpipe made and they put the O2 bung at a slight angle, so when the engine was torqued and the driveline moved, the front driveshaft u-joint would smack right into the O2 sensor. We heated up the pipe and bent the bung, and there's no more binding (still some knocking at higher RPMs though). Also, I had kept the '91 power steering pump in place, and it is 2-3 mm shorter than the '96-99 pump, which was causing some belt chatter on the front bracket. Still a couple of small noises but everything seems to be working and I've got it home.

Cool! :thumbup: