Transfer case or rear diff trouble

I'm having a problem with the car, and I'm hoping someone can help me out with troubleshooting steps to prove if the issue is with the transfer case or the rear diff.

The problem started today while driving. I felt a lurch and heard some banging/rattling sounds. I ended up pulling over and having the car towed to my house. Once there I did a little bit:

The car starts and idles fine. It shifts into all gears. Once you put it in a gear and start to let out on the clutch, the car will creep forward or reverse a little bit before it feels like something is binding up, and if you push the clutch in again the car will spring back the opposite direction. I put the car up on jackstands and rotated the wheels, all wheels rotate as expected with no abnormal sounds when the car is off. Once the car is on and you're attempting to operate it with the clutch/throttle, the problem appears. It happens in forward and reverse.

I removed the driveshaft. Once that was gone the car can move freely in forward and reverse under power. I think that would mean that the problem is inside either the rear diff or the transfer case, and I'm not sure what to do to isolate it in either direction. Any thoughts?

Thanks~

 

If its fine without the driveshaft your problem is in the rear end.

The PTO is part of the transmission so removing the driveshaft wouldn't effect it.

 

Okay, thanks. I wasn't sure if the PTO could be binding only if it was driving the driveshaft.

 

Put the car on stands..

What happens if you manually rotate the input shaft on the rear diff? Try the same at the pto ouput(trans in neutral).

Every bad PTO that I've seen had a visibly cracked case.

 

Rotating the output at the pto worked as expected. I'll have to try on the rear when I put it back up on jack stands, I ran out of time today.

Thanks for the help again

 

Update on this. It is the PTO. When I got back under the car there's a pretty large crack along the top of the case that I didn't see before.

 

It's interesting that the pto behaved normally with the driveshaft disconnected. I guess with the open diff in the front you couldn't really notice pto binding up the one side.

 

Were the beefed up bearing caps the only prevention, or solution to PTO issues? Or is there some sort of heat control issue that needs to be addressed? I remember that they run hot.

I have a Pu so my MS6 knowledge is limited...

 

As far as I know the bearing caps are the only upgrade.

On my last MS6 the transfer case also broke, but that one was leaking and I probably waited too long to refill. I'm not sure what happened on this one. I never launch the car and I was just cruising down the highway. I never noticed a leak with it and I changed the fluid less than a year ago.

 

in matt damond post few years back, they put a cooler for PTO parallel to the cooling system. didnt really ask how they did it but maybe they just put a cooler core inline the hoses that goes to it... but ill prolly try that