Last week as I was accelerating to get on the freeway I hear aloud grinding nose than disappeared after about 15 seconds, sounded like I was dragging something. Today a week later I'm driving in town and feel the transfer case clunking like it does when I turn the dash switch to go into 4WD. I treid moving the selector switch to $H but go nothing, then back to 4H and nothing. I then tried 4L (bad move as it locked in 4L) It took 10 min to get it out of 4L flipping the switch back and forth, backing the truck up etc. Finally shut it down called the wife to let her know what was going on and I had a70mile drive to get home. Started the truck up put the auto transmission in gear and the transfer case popped back to 2H or 4H I do know which, only indicator light that would come on is the 4L. At one point coming up the hill from Carson city to Tahoe there was a distinct rattling sound, marbles in a tin can type which lasted for about a mile then disappeared.

Any ideas, truck is in a shop now we have no Ford dealer close by, they aren't sure what's going on either.

 

I seem to recall this might be caused by a vacuum leak. You might try a search using "vacuum leak 4WD" as a search string.

- Jack

 

Jack that's kind of what I was thinking but didn't know if this system was electric or vacuum actuated PLUS.....

Funny thing the shop just called and said the same thing, the clunking, grinding noises were the frontend trying to engage or not fully disengaging. Transfer case is clean no metal in it

The rattling nose they think was the front hubs trying to partially engage and I was pulling a hill. Had visions of the old Vacuum windshield wipers slowing down or stopping while pulling hills......yep, I'm THAT old!

So you nailed it right out of the box, THANKS!!!!!

Bob B

 

Now and then, this fuzzy old brain actually functions! But, glad the dealership was able to figure out the problem too. They're the ones that matter!

- Jack