so about 2 weeks ago i actually started trying to fix my four wheel drive on my 1992 s10 blazer. i found out my 4wd didnt work last year stuck in a snowbank after my flexplate broke >:l soooo i jacked all wheels up, so all of them could spin freely. opened the hood started the truck engaged the 4wd put it in drive and nothing to the front wheels tried both 4high and low. i heard all clicking as proper and i just changed the encoder motor so i know electronics werent the problem. i undid the battery while the truck was still running. then took the battery pan out. vacuum was holding and pulling the cable as it should. the front driveshaft to the transfercase was spinning like it should...so i shut the truck off. undid the cable started pulling on it and i could here a clicking when i pulled it fully. so i decided from all that info to drop the front differential carrier (front axle) after a huge fight and a knuckle bust to the bone. i got it out. i took it all apart up to the point where it when into the pinion gear, now i turned it all by hand and the drivers side was still on so i could see it turning...so i put the main drive gear into the axle again just the gear not the whole assembly on the passenger side. and if i hold one side the other side spins like it should and if i turned the drivers side wheel it would turn the passenger in the opposite direction. so all was well. i started realizing though when i put the axle arm from the passenger side and just pulled the fork with my finger that the coupler actually would disengage from my main drive gear so when the coupler is pulled to the axle tube (passenger side) the main drive gear spins but isnt transferring that motion. so the motion is peg legging so to speak to that side cause its the easier side to move... with no coupler on. so i put the axle back in after filling it with gear oil and i hooked it up without hooking the cable back to the vacuum actuator...i turn the truck on and press the button truck has 4wd now....but technically the front axle would be engaged at all time in that matter.....can somone please help me im stumped. idk why the coupler was only about half way on the main gear and when the coupler gets pulled it actually disengages instead of engages like it should.

P.s. i have read and researched everything for 2 weeks. on this forum and havent found ANYTHING like this closest thing was someone opened there axle up and was missing the main drive gear. haha i have all the components in mine from what the parts break down in the autozone manual said online.

 

Stupid easy question: Does the vacuum actuator pull the cable all the way so the coupling is fully engaged? I have heard of times when this area sticks and only engages the front axle half way making a no front 4x4 action problem. I just recently replaced all the vacuum tubing fron the front to the transfer case and then to the actuator because of lack of good vacuum..... Now that thing sucks immediately and doesnt lag. Also, check the link in my signature. There is a hell of a good write up on this whole procedure.

 

yeah the actuator engaged all the way the problem with it engaging all the way was it was pulling so far it actually disengages the main drive gear from the coupler the main drive gear only was sitting about half way on the coupler then when you push the button the actuator would pull the coupler over to the axle shaft to far and disengage it know what i mean? its a real PITA i dont understand how the main drive gear can pull in and out and how the coupler is expected to return back to sittin on the main drive gear fully know what i am saying?

 

I can picture that, but never have dug that deep. Hopefully someone else can chime in here and offer some been there done that advice.

Nothing around the actuator had been bent? Maybe if you find a way to make it so it doesnt pull as far it will work for you.? Manually engage the line with vice grips and see if you can get it to work and maybe just adjust the actuator linkage so it doesnt pull as far. Remove the vacuum line from the actuator then engage to a nice spot with vice grips and see if it holds 4x4. Then if it does hold adjust your linkage so it doesnt pull as far and you'd be good to go.

 

There shouldn't be any way that it could disengage from being pulled too far. The room that there is in there just shouldn't allow it. THIS THREAD has a few pictures that shows the parts involved. All those parts fit in there fairly tight with little play. The collar just can't push off the end of the passenger axle shaft gear. There is supposed to be a washer on the diff side that holds the stub shaft up against the passenger side axle shaft & gear.

 

Thats the answer. With pics. Good job Swartlkk your brain is a Blazers best friend.

 

Thanks, I don't even have to ask the question and I get answers. You guys are GREAT, let me buy a round!

 

i would love to put pictures up i just put it all back together the main drive gear coming off the differential is that suppose to be free moving like left to right if the drive axle is laying horizontally? cause mine goes in so far that when i put the coupler on the gear the main drive gear only sits on it about 1/2 way then when the coupler gets pulled it comes off... i wish i would have taken photos i knew i should have, am i making any sense ? thanks for the replys so far


i could use a round right about now

 

As can be seen in the pictures found in the link I posted, #23 should have a washer behind it that both holds the stub shaft up against the end of the passenger side axle shaft (#1 in the schematic above) and keeps it from pushing into the differential case. There shouldn't be much of a gap between items #9 & #23 when fully assembled and there also shouldn't be much of a gap between #9 & #7/#5

 

yeah that washer is there it has the little lock tabs on it, now i guess im curious also how the 4wd disengages without anything actually pulling that coupler back