Ford F 250 major problem and no clue
 

Well I don't know what to do or where to start. For about two weeks now I have been experiencing my truck slipping out of gear while driving. It does when I seem to.come.to.stops and corner the most. When it does pop out of gear there is a grinding sounds like no other. So I turn of my truck right away then it will be rolling when it's in park. I have to push it backwards and shift the column through gears to get it to pop back in then noise is gone. It will pop of of 2 wheel and 4 High. I need to figure out which route to go because without my truck I am screwed. Please respond

Sounds like transfer case problems to me. If it pops out and then you leave the trans in drive but try to move the transfer case lever and all you get is grinding while you are sitting still, that tells me the trans is working and still turning.

Do you have a body lift on this truck?

See it's does it when I am.driving at all speeds and what happens is it grinding and I stop. Then when I come to.complete stop and in park it rolls. Then sometimes I can't get it back into to wheel so I go to the transfer case and try to get into high or low and there is grinding when at stop while doing that

Still sounds like the transfer case has a problem. The rolling is a clue to that. If the transfer case releases for some reason, it disconnects the driveline from the transmission, so you are just rolling free. While you are sitting there with the trans in drive and the motor is still running, the trans is still turning, it thinks the truck is still going down the road. When you start messing with the transfer case, that is where all the grinding is coming from.

Another clue is during one of these episodes, when you go to put the trans in park it grinds and clicks. That is another clue that the trans is still turning, even though the truck is not moving. It would be the same thing as putting the trans in park while the whole vehicle is still moving.

If all this is adding up, I would get a pan and drain the oil out of the transfer case. If it looks black or brown and has a lot of metal shavings in it, I think that would be another clue there is something wrong with it. Before you spend any money on it, you might want to get someone else to look at it. But you can get transfer cases at the junkyard, they are not that hard to get last time I looked. Go to Car-Part.com--Used Auto Parts Market and load in all the info and it will tell you local junkyards that would have a transfer case to fit.

Didn't see an answer to this question. Even if not lifted, peel back the carpet and transfer case shift lever boot. Make sure the lever travels full travel in both directions, with adequate clearance from the body, carpet, or anything else that could interfere.

In a sharp corner, the body and frame could flex enough to touch the lever and bump it towards neutral.

Check the rubber mount between the transmission/transfer case and the crossmember. If the rubber has deteriorated, the whole assembly could move in response to torque loads. That might make the lever contact something.

if you have an NP 208 they wear out where the shift fork contacts the drum. the first ones had nylon on the groove and a metal shift fork. later models had a metal groove and nylon sleeves for the shift fork.
when I bought my 1980 Bronco it needed work and they had the transfer case lever secured underneath with a coat hanger so it would stay in 2 hi.

I bought a drum, shift fork and some bushings from Cobra transmission and fixed it.

the transfer cases are very simple I had to buy the seals too. one place uses two seals pressed in I think its the output.

the rtv part isnt fun but part of it.

I have never been in one, but I have heard they can leak, get low on oil, and overheat. And that melts the plastic you are talking about.

Curiously, the Ford service manual calls for RTV to assemble the case halves. Years ago, I repaired a similar aluminum-bodied transfer case on brand C and that service manual called for anaerobic sealer. Here's one example from Permatex:

https://www.permatex.com/products/ga...lange-sealant/

Given my druthers, I much prefer anaerobic sealer over RTV. During assembly, RTV squeezes out and makes little rubbery worms that can plug oil passages. That exactly what I found from an existing repair by a previous owner. The oil passage to the input bearing was plugged with RTV worms. The bearing starved for oil and spun after seizing up, which destroyed the front case half.

Anaerobic sealer, on the other hand, won't do that. The squeezeout stays liquid and remains harmless. The only part that cures is the stuff between the flanges. It's like magic, knowing where to cure and where not to. I love the stuff.