Hey guys, got a problem that I can't figure out. My truck is a '94 F250, about 4 years ago it started making a terrible whining sound every time you downshifted, into any gear. I thought for sure it was in the tranny so I swapped it. But to no avail, it ended up being the transfer case. I learned that it was full of 80-90 from the prior owner, assumed that was what burned it up and swapped it out, making sure the new case was filled with tranny fluid. Now a week ago while home on R&R from Afghanistan it started doing the VERY same thing. You can shift up without a problem, into any gear, but as soon as you downshift it makes a whining sound and is slipping, won't go until you come to a stop and start out at first again. My question is, Whats the problem? What is the root problem? Can I rebuild it? And how can I prevent it from happening again? ANY input would be great, I can't do anything with it until I get state side again in 6 months, but knowing where to look when I get back would be great. Now I'm wishing I had torn apart the last one..

 

Is this a manual or automatic truck? And did you convert from one transmission to another? (auto to manual swap)? I'm wondering if the shift linkage for the transfer case isn't letting the TC get all the way into gear. There is a bar that needs to be changed (or modified) to a different length when swapping from auto to manual and if that wasn't completed the TC may not be fully in gear when the shifter in the cab is in the notch for 2HI. That's my WAG at this point anyway.

Maybe try getting under the truck and moving the shift linkage by hand to see if it feels like it is locking into the 2HI detent when you have the shifter in 2HI in the cab?

 

Its a 5 speed truck, always has been. And it does the thing in 2H, 4H (hubs unlocked) and 4L (hubs unlocked) The transfer case seemed to be shifting just fine, with the first transfer case and now this one.

 

I also just picked up a '96 F350 that was converted to a 5 speed from a auto that has a problem shifting/staying in reverse, but I'm pretty sure with that truck its the transmission..

 

Also, while the current transfer case was used when I got it 1XXK miles, I've only put maybe 15K miles on it.

 

I'm not sure then. I think I would still crawl under there and see if it is fully engaged in gear just to be sure. If it is locked in gear fully and it is still doing it, it really sounds like the TC is toast. That's an odd one. Hopefully someone else will pipe up with another suggestion.


Oh, and THANK YOU for your service to our country. At the very least, we all owe you a debt of gratitude.

 

I see in your signature you have a Southbend clutch. Did you convert it to a solid flywheel when you did the clutch? If you still have the DMF (dual mass flywheel), that could be the problem. If you don't have the DMF, then I would check the rear axle. Could be coming from the ring and pinion. I'm can't imagine both t-cases having the same problem, or what on the truck could cause truck could cause both t-cases to do that.

 

I'm getting a slight whine in each gear as well. I chalked it up to just having the new ZF. Maybe I need to do some more investigating.

OP, thank you for your service!

 

I did change it to a solid mass when swapping the clutch, and its def not coming from the rear end. I'll pull it apart when I get back, I'm just confused as what could possibly be wrong

 

Yeah, the fact that two different t-cases are making the same noise confuses me too. Is your carrier bearing good?

 

Nearly brand new

 

And the tranny is slipping??

 

Its not the tranny, thats what I thought the problem was at first (or the clutch), but after the first TC went out, I dropped the tranny, clutch was A-ok, replaced the tranny thinking that HAD to be the problem, it sounded like the noise was coming from the tranny without a doubt. but after replacing the tranny NOTHING changed. Swapped the TC and it was good to go, no noise at all, until a week ago. So its def the transfer case, the noise and symtoms are the very same as they where 3 years ago. I'm just not sure what could have broke in the TC and why. Being overseas and not being able to tear it apart is driving me nuts..

 

And its not a slight whine, it sounds like its breaking teeth off of every gear in the tranny, and slips, when downshifting, until you come to a stop. You can give the truck every ounce of power it has shifting up without a problem, but no matter what speed, RPM, or gear, you CANNOT downshift. Just screams at you and slips, until you hit the clutch or come to a stop. Baffling as hell. And this is the ONLY truck I've ever had a problem with a TC..

 

I have yet to find anybody with even a wild guess at what could be wrong with 2 TCs that would do that. It makes no sense for the problem to be in the TC, I just don't see how downshifting could affect it, but shifting up, under full power its fine..