My 97 F250 Heavy Duty with 320K miles lost high range in transfer case. Just driving along light throttle or coast. No noise. Now it only has low range, it still shifts in and out of 4x4. It has a Borg Warner with no PTO opening. Any body have this issue, nothing came up on a search.

 

Sounds like the shift fork may have broken. Oil pump failure is pretty common in the older BW 1356 cases, but you should have the much larger Borg-Warner 4407 case in your truck.

At this point, I'd say your only option is to drop the case, open it up, and see what you find. Be careful removing it though, it weighs over 100 pounds by itself.

 

Looking at all that aluminum you could almost think it would be less weight, but a lot of steel inside. I will have to rig up the trans jack to match the angle.

I was just wondering if anyone else experienced something like this. When I rotate the shift lever off the case, it feel normal. All detents are there, it goes in and out of 4x4. It is very aggravating that there was NO warning prior to it happening and 3 hours away from home!

Will drop and split.

What does the oil pump do? Is it just lubrication, or some kind of pressure clutch pack?

 

It just lubricates the transfercase. Like I said, I've never seen inside of a 4407 case, so I'm not sure if they redesigned the oil pump compared to the 1356.