i get a "thunk" or "pop"
 

Hey guys,
I have a 2000 trailblazer with 4 wheel drive auto. I have other posts out there about my highway vibrations, but this is about a possible tranny problem. I did have my tranny checked out, but I've been noticing that when my truck is down shifting, just before I stop, I get a thunk or pop noise, and I can feel it under my feet, more towards the psgr side. Any ideas. I'm convinced this truck is gonna send me to the poor house:icon_doh:
Also , don't know if this matters, I was reading a post about 4wd, when I'm in 2hi, I cannot turn my front drive shaft freely big hand, it seems locked. Is that right?

Ok, today I was in my truck and I figured I'd see if I get it in 4wd. So I push my 4 auto button, and I noticed that I didn't get that click from under my dash, or psgr kick plate. Then I tried 4hi, and no click again. But when I went back to 2hi, I got the click. After that I didn't really seem to get that POP on the down shift. Hmmm . Now is it possible that I'm actually having a 4wd problem in my differential? The buttons were showing 2hi when I keyed in, but it didn't seem like the truck performed any type of actions when I switched to 4. Does this make any sense

Did the desired light illuminate when you selected Auto4, 4hi, etc? If so, it shifted properly and there is nothing to worry about.

As I have stated in a LOT of threads concerning the front drive shaft with the NV236 transfer case, it will always spin. If you want to find out why, type "NV236+preload" into the search bar.

As far as your thunk/pop... Could just be drivetrain slop that you are hearing. Maybe nothing to worry about. Could be a motor mount that is starting to go... I say turn up the music enjoy your truck.

Funny, the music thing seems to be working

Sometimes odd noises can drive you nuts and cause you to dump money needlessly in an attempt to "fix" what might not really be a problem.