I have decided to de-virginize myself on this board with a post about my daily driver (ack).

Deal is I have a (hold your laughs) '90 GMC K1500 Z-71. Yep, complete with 'Off Road' stickers on the side. Anyway, for the past the year or so I have experienced trouble with the 4wd disengaging.

First, I have replaced the POS thermo actuator with the dealer electro-mechanical actuator. This has helped in going from 2wd to 4wd, but not the opposite. Also, last spring my brother and I took the front diff. assembly apart, to look for anything obvious. Didn't see anything like a broken return spring, burrs on the collar gear (whatever its called), or anything that just plain looked wrong.

Now, I know there will be some delay when shifting from 4wd to 2wd. But I don't think 12 miles can be normal! And thats partly stop and go traffic.

So any ideas? Besides 'throw out everything IFS'.