4x4 thunk
 

Hey guys quick question. I tried searching but couldn't find anything. 04 f150 140,000 miles new body style. I just tested my 4x4 today before we get some snow. At about 10 miles an hour I heard and felt a real bad thunk and about 100 yards later it did it again. I turned off 4x4 and it quit. I haven't had 4x4 on since last year. Possibly tcase fluid or dif fluid? I'm guessing neither have been changed on it since new. Any suggestions as to what it could be? Thanks guys

Verify that the iwe system is operating.....

You also might want to change the fluid.....

Also check tire pressures....

Thanks 88 for the quick reply. Correct me if I'm wrong but the IWE controls locking and unlocking of the 4 wheel drive right? My truck is definitely locking in 4 wheel. I've heard there would be a grinding noise if its trying to unlock itself and I dont believe its trying to do so as all tires were still spinning when this happened (i punched it for a split second on wet roads right after first thunk). I didn't hear any grinding and it didn't really act like 4 wheel wanted to disengage. That's why I'm at a loss. Let me know what you think. Thanks again

You could also have issues with the tcase motor only partially engaging the the shift fork or the shift fork itself might be damaged.....

As long as you verified the iwe system is operational then that can be eliminated as being an issue....

In my 06 there was always a slight noise when the 4wd was engaged....it wasn't a clunk though ....

Ya there has always been a slight noise in this one also but not this bad. So this morning after work I drove my truck home in 4 wheel drive just to see what happened. There were no noises the whole ride until I pulled into my drive way. As I'm rolling to get in my garage, I hear this thunk that scared the S outta me. It was so loud I thought I hit something. However, I do think its coming from the driver side, and possibly somewhere in the steering components. Could this possibly be a bad u joint or something along those lines?

Oh and if it helps I wasnt giving the truck any gas I was just rolling in at idle speeds.

I had a similar issue with my 98 right before the T-Case let go. Mine "popped" and "banged" several miles before it finally quit. The fork in the T-Case was bad. -Alex