I just bought an 89 f250 7.3 4x4 5 speed. Its been sitting awhile and a lot of things still do not work on it. I've been driving it everyday for the past week, in the morning when the truck is cold i'll be going down the road and ill here a loud clunk and all power is lost to the back wheels. I have to coast to a stop and put the transfer case in and out of 4 low and nuetral until it catches and I can go again. I usually have to do this about 10 times before the first mile, then it only drops out every once and a great while. The clutch still is good, and the tranny shifts pretty smoothly. I just do not understand why the transfer case is doing this. I still havent tried locked the hubs in yet, but if I put it into 4 hi or 2 hi no power is given to the back tires. If anyone could help me out it would be greatly appreciated.

 

it would be interesting to put it in 4hi with the front hubs locked and start out in it. it may not do it anymore, or just the rear, or both front and rear may drop out.

i have not thought through would this would tell us, but the more info the better.

 

Sounds like 4x4 is popping in and out.Make shure the 4x4 shift is pushed all the way down when the engine is in N.Some times you need to work it.It will feel tight at first when pushing it down, then it should go into place.It might need to be used for a while.Drive it in 4x4 for a while just be easy on making turns on the road.

 

How many miles are on the truck, poping out of gear is usaly caused by worn out shift fork in the transfer case, the borg warner 1356 is known for wearing out shift forks and oil pump failaure. since the truck been sitting for awile it might be a good idea to check the fulid in it

 

I was talking to a friend about this thread last night and some thing like this happin to him.He was pulling a big boat out of the water and he had to use the E-break and just before he let the E-break go pulling up a wet hill the same thing happen, he lost all power to the rear end.It was a 88 and it never did it again.

 

I am going to check the oil in the t-case today. I thought about running 4 hi with it locked in for a while but I can not get it into anything but 4 low and 2 hi. When it is in 4 low I can run it in 2nd gear but when I shift it drops out again, and it usually only makes it 100 ft before all power stops to the wheels. The problem usually happens when I am shifting gears going down the road. I push in the clutch and move it up into the next gear and something goes clunk very loudly underneath. When I move the t-case lever it does not always go in and out of 2 hi and 4 low. I usually have to go back and forth until it slams itself into 4 low, then I have to work it to get it back into 2 hi so that I can continue down the road. When the truck is in 4 hi, is the light on the dash supposed to be illuminated as when it is in 4 low. The t-case lever just wont go into 4 hi, cant even feel that its there. There are about 150,000 mile on the truck.

 

Does your truck have a body lift on it?

Part of your posts almost make me think there is interference between the body or frame and the transfer case linkage.

When I installed the body lift on mine, I had problems with the transfer case shifter hitting the floor pan.
2 wheel hi was the worst.
Wonder what the chances are you are running in 4x4 high, the body is blocking the 2 wheel high position, therefore you can not find 4x4 high

The dash light should light when it is in 4x4, hi or low

 

Sorry there is no body lift on the truck. I can feel the position for 4 hi but it doesnt engage and it is easily pushed into 2 hi. Today I had to go back and forth between nuetral and 4 low just to get 4 low to engage(NO power anywhere). In 4 low I can limp along at an idle but when throttle is appied it clinks out and I lose all power again. I locked the front in today and at an idle in 4 low power does go to the front but when I gave it throttle it clunked out again.

 

i have a 94 f25o and I can't get any power to the rear either, when I put it in 2hi and shift into drive it won't ever drop all the way down into first gear but after second it is fine up through the gears and back down to second

 

i have a 94 f25o and I can't get any power to the rear either, when I put it in 2hi and shift into drive it won't ever drop all the way down into first gear but after second it is fine up through the gears and back down to second

 

Check the shaft that goes into the transfer case for the shift linkage.

Mine had similar problems and I found the the shaft and housing were so baddly worn that the peg inside the the case that moves the shift cam would jump out of the cam. I replace the cam and the shaft and the scilencers on the shift fork. I took the housing to a machine shop and they bored out the housing and installed a bushing.

Problem sloved!

While I was in it that far I also replaced the chain and oil pump.

I hope this helps it is a lot easier to see when it is apart and you can watch the peg jump out of the shift cam.

 

I've got an 89 f-350 7.3 w/ the five speed that does a simaler thing: when i'm driving and let off the throttle the transfer case pops into neutral and I have to pull over and pull it into 4-low then back to 2-hi. turns out that my linkage actually broke off the side of the tranny and with all the extra slop it wasn't fully ingaged into 2-hi, so when the load was off the transfer case it would fall into neutral. If thats the case a bungy cord made a good temp fix.


Beersy50

 

I finally ended up pulling the t-case off of the truck. WHen I opened it up I found that I had the same problem as Chris1066. The shaft that runs into the t-case from the linkage had worn an oval into the t-case casing. This caused the shifting plate to push away from the shift fork, thus the loss of power. I know I should have had it bored and replaced with a larger shaft but that cost money that I do not have. I just went down to Ace Hardwre and bought a $1.83 worth of stainless washers(I believe it was 3 in total). I popped the clip holding the shift rod to the plate on the iside of the t-case. I then placed one washer on the outside of the Tcase and two directly beind the clip on the inside of the transfer case. Everyhing works perfectly and I rarely if ever have any problems with it(Tends to pop out in super sticky mud, but thats taking off in second gear sittin in the middle of the mess). I beleive it took me about 4 hours to pull the driveshaft, remove the transfer case,and fix the problem. Its been almost a year and everything still runs. Dont be afraid to take the transfer case apart, it is no where near as complicated as it may look.
(P.S. The poping out of gear will only get worse with time. The first week I had my truck I had no problems at all, the mess started when I tried to use 4 low with the hubs locked out. I think it broke all of the componants lose that were stuck within the t-case. Fix the problem as soon as possibe, the longer you wait the more metal shavings you'll find when you eventually do ope it up).

 

You should have priced it. I think they only charged me fifty dollars that time. To put the bushing in. I also tried the washers and could still get it to jump by hand. I was mud dragging my truck at the time and the bungee cord would no longer hold!

You are right fix it right away it dosent take much and the bungee cord only lasted a week for me.

 

Well I realize this is an old thread but I'm currently experinceing the same situation. As you can read from my reply earlier in this thread I suggested a bungee cord as a temp fix, well I should of fixed it then, because now I can barely drive the truck. Although fabing new external linkage helped it didn't solve the problem. After reading the final two posts from gonecrazyi and chris1066 I decided to pull the transfer case today. Its setting on my bench and in the next day or two I'll take it apart. If anyone is having the same problem I'll post a day by day update on my repair. And as for what gonecrazyi said about how easy it is to fix, I hope he's right. So far I had 1 1/2 hours in pulling the transfer case by myself and on my back lawn, so far so good.

Beersy50