I bought a 1999 F-350 crew about a month ago. It runs fine, and I've pulled a 7,500 pound horse trailer a half a dozen times and put about 2000 miles on it from the time I bought it.

A couple of weeks ago after returning home, and after backing up and going forward several times, the truck wouldn't drop into drive. It would go into first, and reverse, but no drive.

The next morning, it shifted fine, through all the gears.

It's gotten progressively worse, and today I flush the transmission and replaced the filter. The fluid was dark and smelled burned.

After I finished I took if for a drive and it shifted beautify, so I backed up and hooked up the 4000lb horse trailer. Pulled fine, drove it 40 or 50 miles and up some steep hills then back home.

Again, while backing in the trailer, which requires me to shift forward to reverse and visa-versa, the truck quit pulling, and now won't pull in first.

My guess is it'll pull fine again when it cools down.

Any idea's or do I need a new transmission?

 

If its a four wheel drive it would help to put it in 4 low when backing up the trailer. You are creating a ton of heat on your trans doing it that way and eventually it will be toast.

 

Good advice, I didn't think about that. So reverse is working the transmission harder than a forward gear?