Drove to a downed tree on wet ground. Shifted into 4 low then heard a horrible bang from transfer case area after i started moving. Now its stuck in 4 low, tried everything except jacking it up in the front to get it out of 4 low.

haven't begun taking a wrench to anything. Mostly because im not sure where to start. Any ideas why i got a horrible bang from under the truck? Transmission shifts fine, all drive lines are still in tact.

 

 

What transfer case ?

It's not uncommon to have to get under a high boy and mess with the shift linkage it can be a pain.

 

Be on a none hard packed surface, dirt, ect...gravel.
Truck not running/in park, try to shift into N or 2H. No go...
Then start truck, let idle, in park, try to shift into N or 4H. No go...
With truck idling, foot on brake, put in D and apply steady constant xfer case shift lever pressure (by hand) in the N direction. Let off brake and as truck rolls fwd, see if it will come out of 4L into N or 4H.
No go... brakes, shift into reverse, again with pressure on xfer case shift lever, let off brake, see if while idling and rolling/moving in reverse if it will come out of 4L.
No go.. then try all the same with a little throttle blip/quick tap one or twice. Like the tap to get the choke off high idle early. Roll backwards for like 2 or 3 ft.

 

Did the trandfer case shift normal before the pull ?
Did you for sure get it all the way into 4L ?
Have you tried backing up a little, maybe 2 or 3 feet as you try pulling the transfer case back into N ?

When I'm gonna pull with 4L I'll use my right hand on the transfer case lever to apply pressure forwards to make as sure as I can that it doesn't pop back out. Seems to me that once many years ago mine popped out, but suddenly just the front axle was in low, like the rear popped out and suddenly was just pulling with front. I don't think the lever moved any, it was more like I just didn't have it completely in 4L. I don't recall exactly. I'll have to study the linkage. It's a faint memory but it's why I always apply forward pressure as I start pulling a load in 4L. I do recall it doing it once when first bought in the '80s, was pulling a camper on a steep hill. That was the catalyst to me applying pressure as it takes up the pull. It maybe was me just not having it "all the way" in 4L ?

If you look at linkage, it moves two shift rail type rods. First one gets pulled / pushed, then the other follows as there are 2 interlocks in the transfer case. I made notes on a photo a few years back to help me understand it, Try backing up a few feet on a slight grade, let it roll in neutral on the transmission, SLOW ... and as it moves, apply some pressure pulling the transfer case lever from 4L just to N. Once in N, shut engine off, then pull transfer case lever to 2H .... and restart engine in park or neutral as normally you do. If a NP 205, ain't but 4 transfer case positions. Going from 2H where we all run them most often, there is only 3 movements one can do. Going to 4L is a two step through neutral.

 

An explanation why you some times have to shut the truck off to prevent xfer case shifting grinding.

"With trans in neutral and clutch "out", the input shaft is turning and "internal windage" as the trans lube is swirled will still apply a rotation to the output shaft when there's nothing to stop it turning.... like when you slide the TC into neutral on the way from 2hi to 4lo.

Mine has a C-6 and while I can shift from 2hi to 4hi with trans neutral with engine running, I need to stop and place trans in PARK before going from 2hi through TC neutral to 4lo for similar reason.

The deal is when that TC hits neutral, there is nothing to stop it's input shaft from turning, and that meansnothing to stop the transmission output from turning .... (except in my case when I place C-6 in Park the park pawl locks the trans output shaft) ..... and in your case, pushing the clutch in will minimize it. If your clutch dragsa hair, you'll maybe need to shut your engine off .... in which case the clutch needs adjustment."

 

I maybe got so wrapped up in my research & searching my memory, I somehow just thought "LiveFrom77f150" had a C-6, but it might be a 4 spd?

 

Own a 79 F350 4x4 and had the same issue. Put truck in reverse and moved 10 yards and shifted out of 4L with no issue. Instructions right out of my ford owners manual. Easy and did the trick.

 

The only terrible bang that I have ever had was a Hub that was not completely engaged. The **** was turned to lock but the spline only partially engaged. When I started to pull a heavy load, the hub on the drivers side, popped out of engagement and sounded like a gun shot. (very loud) But had no issues returning lever to N

 

Have had the same noise, but when the t-case actually shifted out of gear. Doesn't sound like that was the OP's issue.

But what has kept you from simply backing up until it releases (if it will), or just jacking one or both tires off of the ground to see if that releases pressure?
Neither one takes much effort, especially the backing up part. Sometimes it takes just a few feet as someone mentioned, sometimes it takes quite a bit. My D20 t-case was a buttery smooth shifter and I rarely had to back up to get it out of 4wd. But once or twice I had to back it up for at least 20-30 feet before it could be pulled out of 4-low.
My other D20 and my NP205 both always put up a fight. The D20 in that rig does not want to shift into or out of 4-low and the 205 doesn't like shifting out of anything!

Hopefully the bang was just a hub or something simple. Or something inexpensive if it did break.

Good luck.

Paul