4wd clunk when engage and disengage

i love this site. it has helped me greatly in solving my 95 blazer's "problems". now here is another "problem" my blaze is suffering. the other day, snowing and icy, i engaged the 4wd to get moving from a stop light. all was good until i started rolling. all of a sudden there was a wicked clunk like i had hit a stump with the frame. i stopped and looked underneath fearing something was going to be laying on the road. nothing was hanging nor leaking so i drove away, slowly. cautiously i disengaged the 4wd and there it was again "CLUNK". can anyone give this fairly green wrencher any ideas as to what is causing it? there isn't any vibration or anything in 2wd. only when engaging and dis. help! thanx.

Using your 4wd on hard pavement can cause your Tcase to bind, so I'd be careful with that...

Check the fluid level in your Tcase by removing the top filler plug and sticking your finger in. It should be no more than half an inch below that filler hole.

As the guys here said to me a while back ----- How are your tires?

T

my 97 does that do its not very hard, but u can feel it clunk, its just the T-case syncing up for 4x4, and when u take it out the teeth are just slding out, almost like taking it out of a gear while moving on a manual tranny in a car. Is that the first time is done when going to 4x4?

i will check the fluid level tonight.......tires are good. not much tread wear, i was going to rotate them tonight too...it is the first time it has happened. i havent used 4wd since. thank you all for your input. much appreciated