Not Just Another Inop 4X4 Problem
 

I just bought this 96 Blazer 4.3L W and when I drove it the 4X4 locked in perfect. Now we get another snow fall and it dont work.

Ive narrowed it down to the front diff. This is where it gets specific. If anyone has ever tore one of these diff's apart. The cable pulls a fork which slides a collar over splines to lock the front axle. Thats where my problem lays. If I take the cable off at the diff, and pull the lever by hand and rotate the tires slowly I can feel the collar just about to slide all the way at each tooth but then it goes over it. Kinda seems like the gears are a bit grinded and wont let the collar slide over them. If I put the truck in 4X4 and hit the gas, the front diff just clicks.

My question is has anyone else had this problem? If so what did you do about it? Im pretty sure I will end up taking the housing apart this weekend and see if I can file the teeth down a bit to let it lock.

Any other ideas? I think the cable wasn't adjusted all the way and the collar has been riding on the tip of the teeth and now grinded the teeth a bit not allowing the collar to slide all the way over the spline. If no one has anymore ideas I will find out the weekend.

Thanks

RE: Not Just Another Inop 4X4 Problem
 

If you cannot get it to engage by pulling on the fork in the axle, then you will likely have to disassemble it.

When you do, please do take pictures. It would help a lot of people be able to understand how the whole system works. I have had one apart before a very long time ago (85 S10), but that was before digital cameras and way before I was this active in online forums. I have been temped more than once to just head down to the local Pick-n-Pull and take one apart there just to get pictures. If you have some time to write up a DIY article, please consider that as well.

Anyway, back to your problem, you will likely have to file down the leading edge of the gears. They should be beveled on the sides of the spline to aid in engagement. Hopefully yours is not chipped like the one in the front of my old S10. Mine chipped the splines on the axle and split the collar from being partially engaged under power (what it is to be young and naive).

RE: Not Just Another Inop 4X4 Problem
 

Yea I had the perfect chance today. Im a mechanic, and one of our other guys at work just rebuilt the front diff on his 92 Chevy Pickup, looking at his torn apart today is how I understood how it worked. Once I looked at his I knew the teeth had to be messed up. Ive taken a diff out of 1 Blazer, and remember it was a pain in the ass. Im hoping I can just tear apart right side where the collar sits. But either way when I get to it I will deff. keep my camera on me.
I searched and read alot of threads on Inop 4X4's and theres alot of repeat questions but also alot of questions that can be answered easily if you have a basic understanding of the system. I think the diff is where everyone gets lost.

I will deff. take pictures and do a write up. Sticky on its way... Until then here is a picture of what im talking about..
http://i43.photobucket.com/albums/e3.../FrontDiff.gif

No.1 Is the right axle and has splines at the end of it.
No.23 Slides into the carrier and has large teeth on the other end
No.17 is your fork
No.22 Is the collar it has large teeth inside it that mate with No.23

The collar no.22 rests on the axle No.1 the fork wraps around the collar. Then you push the 4x4 button or shift your transfer case into 4x4 it starts spinning the front drive shaft, which spins the carrier and the short shaft No.23. Now your in 4x4, BUT the front axel needs to lock the right axle (left axle in picture) with the carrier. A switch on the transfer case routes engine vacuum to a diaphram under the battery tray, that diaphram pulls a cable No.10 which pulls the collar No.22 and forces it over the short shaft No. 23 Now your front diff is locked. When you take it out of 4x4 the vacuum switch closes and a spring No.16 pushes the fork and collar off the shaft unlocking the front diff.

The problem with mine I think is that the large teeth on No. 23 and the inside of the collar are worn at the tips, not allowing them to join together, and the more I drove it around with it clicking, thinking it would lock eventually it just wore the tip of the teeth more.
But neways look forward to a write up.

RE: Not Just Another Inop 4X4 Problem
 

You should not have to mess with the differential case. You should be able to get the passenger axle extension tube off, but it may require popping a ball joint, then disconnecting the CV shaft from the axle extension tube, which would allow you to then pull the extension tube.