Squeal after transmission work

[traumamed]

Longtime lurker, first time poster. So here's the story. 1998 Expedition 5.4L Eddie Bauer with 189K miles. I developed a leak in the transfer case and the transmission seals, and I needed a new starter and flexplate/flywheel due to a couple chipped teeth on the flywheel. I decided just to have a shop take care of resealing the transfer case and transmission, and do the flexplate and starter while they had the transmission off.

Got the car back and all was fine...for all of 50 miles. The truck has now rapidly developed a squeal that sounds almost like a belt squeal or pulley squeal, but it's not coming from under the hood. It's coming from under the truck in the vicinity of the transmission. Details about the noise: happens only when moving, somewhat speed/RPM dependent but not consistently, continues to make the noise even when I manually shift it into neutral while rolling, makes no difference if it's in 2WD or A4WD, and a couple of times it has bogged the engine while stopped in gear - almost to the point of stalling.

My first thought is that they botched the transmission re-install and now something is rubbing or a bearing is shot. Possibly torque converter related? Any ideas? I am hesitant to take the truck back to this shop, but I'm not sure where to even begin to diagnose this. I am 100% sure it is not belt-related, and I have strong doubts it could be the drive shaft U-joints as I just serviced those (with good quality replacements) less than 20K miles ago.

Thanks in advance for any and all input!

 

[BULLDOG]

First of all check brakes dust shields, heat shield on the transfer case(front output shaft).
I am pretty sure you will find something bended.

 

[98EXPnSRQ]

Yeah, like Bulldog said, if you can jack the front wheels off the ground, roll them and check for drag or binding, then jack the rear off the ground, put it in neutral and roll the rear wheels. You might have to put it on jack stands or a lift and put it in drive and run it. Sounds like the shop screwed something up.

 

[traumamed]

Thanks for the tips. I have a buddy with a lift and put it on the lift and ran it. The noise was/is originating from the transfer case rear output shaft seal, which is one of the seals the shop replaced. They put a rubber boot over the output shaft, which goes around the drive shaft. Spraying WD-40 on the drive shaft where it comes out of the boot resolved the noise, temporarily. I took it to the shop and told them where the noise was coming from, and they re-packed the boot with grease. They assured me the boot itself was simply rubbing on the drive shaft and causing the squeal when it ran dry. They told me the boot could just be removed, or else over time the area of the boot contacting the drive shaft would just be eroded away and all would be well. So of course, after a couple hundred miles of driving today, the squeal is starting to return again. Anyone think it really could just be this boot, or is a bearing or bushing under the boot more likely and this shop is just feeding me a line of bull? Any ideas aside from having to either re-grease this stupid boot on a daily basis or cut it off entirely?

 

[BULLDOG]

If the noise coming from transfer case rear output shaft, you probably have the sliping yoke worn out.
Seal its just a rubber, its can not make any type of noise.

Check the sliping yoke for play, just hold it and move up and down.

 

[98EXPnSRQ]

Mine doesn't have this boot. Never did. Just a slip joint right into the t-case. You could probably just take it off.