Hey all,

Lately I have been having an issue with my 05 jimmy. it has a 4.3 nv3500, and while I'm in 2wd I am frequently met with a whining or grinding noise, kind of sounding like it's coming from the front differential. When I switch into 4H though, the noise immediately goes away. Putting it back into 2wd is okay for about a minute or two, then I am met with the same noise as before. I have been driving around like this for a few months now, and am starting to get very worried that it will screw me over soon. I would like to get to the bottom of it, without burning a hole in my pocket at a professional mechanic.

I did read other threads about it being numerous different things, such as the transfer case vacuum switch, 4wd actuator, input shaft seal, and the front axle not fully disengaging. I feel like it could be the axle not fully disengaging, but I could be wrong.

This could also be a sign that my jimmy wants to get a SAS lol

All help is very much appreciated!!!
Thank you so much

 

Can't be sure myself but your research of the other threads hit all the ideas I could come up with. The only thing to possibly add is if it is a front wheel bearing. I can't help you with details but I'd start thinking of how I could test which one of those possible failures could be the culprit.

Then again, doing a SAS could be the way to go!

 

Diagram of front differential and 4wd actuator for 2nd gen s10s with manual transmission with 4x4 (in case anyone is curious)
4WD actuator: 15-22
Axle: 1-12
Differential: 23-76
This could also be for automatic transmissions, but since my jimmy is stick, I am unaware weather it is or not.

I am about to order the 4wd actuator along with the transfer case vacuum switch, I talked to numerous ticketed mechanics in my area that are familiar with blazers and they all told me the same; 4wd actuator and the vacuum switch. Going to replace both myself once I receive the parts, and I'll report back to here. Avoiding the aftermarket stuff if possible, without trying to blow my entire life savings lol

Dealership tried to tell me that I needed a whole new front differential, but I am convinced I don't need one and they're just trying to make money off me

Hopefully I can do SAS down the road, when the front or rear differential blows up I'll consider it

 

my vote is for the transfer case switch...

 

I have replaced my 4wd actuator and transfer case vacuum switch, and the problem has been fixed. The ball that is spring loaded on the tcase vacuum switch was completely pushed in for me, therefore making the whining in 2wd.

I used GM Genuine parts, since I can't get myself to trust other brands like dorman. It's a premium for GM Genuine but it's worth it in my opinion.

 

Congrats on getting it fixed!

And thanks for the update.