I started my truck this morning (-21C - -6F) outside temp. Started driving the truck after the truck had been running about 15-20 minutes. As I progressed down the street, I could hear what sounded like a mudflap caught in a tire, which it wasn't then as I slowed and applied the brakes a huge bang that shook the truck. Almost like gears were trying to mesh and then all of the sudden did mesh. Then that same day in the evening I went out with the truck and the same thing happened again but only louder this time. I thought something actually broke. Anyone else having this issue? Truck was in 2 wheel drive. Wasn't going faster than 50kms/hr or 30mph. Almost afraid to drive it. It is going into the dealer today, but I should get the canned response "we cannot replicate the problem" and nothing will be done. I tow a 11,000ib trailer and I don't need this truck lunching out on me when I have the trailer on. Help!

 

Maybe the rear diff locker? You describe a sound that happens about the speed that the locker will engage or disengage automatically. Is the electronic locker **** pulled out?

 

The button was in at the time. The 4 wheel drive selector wasn't or hasn't been touched throughout this issue. Very strange.

 

prob not the culprit but make sure your front hubs are not manually locked. Even if they were I doubt it would make that sort of nice unless in the middle of a U-turn.

 

You might try cycling the diff lock and 4Hi and 4Lo a few times just to make sure they are able to engage/disengage when needed. The 4Hi did not work right off the bat on my new truck until I had used it a couple of times. Maybe it's just a break-in kind of thing that is exacerbated by the low temps.

Forward, backward, on, off, etc. Just run the driveline through it's paces a few times and see if it helps.

 

I did end up cycling through those with the selector ****. I wonder if the actuator is operated by vacuum and the line may have moisture preventing it from engaging fully? I brought it to the dealer for them to trouble shoot. Hopefully it was a one off.

 

I was thinking more along the lines of actually running in and out of all the different positions and putting a few miles in each position. Turning the **** would be of some value but actually driving forward and backward in each for a few cycles would settle it. I guess its possible water could freeze in the lines but I haven't heard of it before. But we're just spit-balling here. Hope the dealer figures it out.

 

Interesting to hear your 4H did not engage until after it had been used a few times. I almost got stuck in a parking lot today with my new truck with a couple of inches of snow and ice. When I put it in 4H it did not do much. That may explain things.

 

This is not strictly in line with the OP's issue but sorta related. I created a thread to discuss the glitchy 4x4 engagement.

https://www.ford-trucks.com/forums/1...l#post16936524