I have a 1988 F-250 7.5L auto with a borg 1356 transfer case. When I shift into either 4H or 4L the front drive shaft does not engage. The transfer case was rebuilt 2 years ago and only has 2000km on it.
When I leave the hubs unlocked and shift into either 4H or 4L and have someone watch the drive shaft when I move forward or reverse the drive shaft does not spin. So... to confirm this I then shift into 2H and lock the hubs and voila, the shaft spins.
So there is no problem with the hubs, it's the transfer case that does not engage the front drive shaft, therefore no 4wd. Other than the front drive shaft not engaging the transfer case appears to shift fine. When I'm in low range the drive drives in low range, just no 4wd.
This truck is new to me with almost every component having been replaced over the past few years, in really good shape. I even have the invoice from the tranny shop that did the rebuild, but they will not help since it's been two years.

Does anybody have any ideas what could cause this??

 

...Welcome to Ford Truck Enthusiasts!

See you on the boards. ….

 

Broken transfer case I presume. I've might have one that will fit. It's coming out of a '87 F350 460/ZF-5. It's in NY, let me know.

 

I just got it back from the shop and as it turns out it was not put back together correctly when it was rebuilt. The shift lever was put in upside down, or something to that effect. Once the tranny shop pulled it apart (different tranny shop) it was a 5 min fix. Phew!!

 

Good deal. Glad to hear it wasn't worse.

 

I had the opposite problem in a 79 Bronco that the front shaft just spun all the time. I could see it spinning through a hole in the floor going down the highway lol. It wasn't full time 4wd and the hubs were always unlocked.