ive been working on getting the 4 wheel drive working properly on my 97 4 door. still dont have it completely fixed.
ill start from the beginning.. last winter it worked perfectly, it would kick in as soon as i push the button and i would have 4 wheel drive instantly weather i was moving or stopped. didnt use it all summer except once i kicked it in just to keep everything free'd up, it worked then. drove it in 2 wheel drive thru the next few months till november when my transmission went out. found a junkyard tranny and had a friend put it in for me. he said when he took my transfer case off he noticed fluid in the vacuum lines so he replaced the switch for me on the transfer case. got the blazer back on the road from replacing the tranny and about a week later it rained real hard and i was at a friends in a muddy field and kicked it in 4 wheel drive and it didnt work. you could hear the transfer case locking in and the driveshaft wouldnt move if you grabbed it while in park but the front axle wasnt locked it. i replaced the actuator, the cable going to the diff. and all the vaccum lines. still wouldnt work. so i took it to a garage and they took apart the front axle, said everything looked fine but there were a lot of metal shavings and the one washer was bent real bad that runs beside the shift collar. so he put a new one in, and it still wouldnt work. what he ended up doing was putting 2 washers under each bolt that holds the cable mechanism on the side of the diff. to space it out a little bit and get it to pull further, that worked but it takes it a while to engage, you have to move the wheel one way or the other then it will "pop" in and sometimes makes a clunking as you move forward for the first little bit. and if you are sitting still it will not lock in unless you move forward or backward a bit. is this normal for these? or should i look for a used front axle assembly?

 

yeah thats normal. the older s10s had that actuator on the fender instead of under the battery which made diagnosing this problem so much easier. i had a 83 i used to manually engage with a pair of vise grips due to my vacuum switch going out every year and i got sick of replacing it. but yeah i would have to pull it then roll the truck a few inches then the gears would mesh up.

ive seen so many issues with these trucks, your best bet is to manually run vaccum to the actuator under the battery with a vacuum pump (or use your mouth if you dont have one) and see if it will engage the front axle. if so then your front axle works, its a vacuum issue. its possible the vacuum line going to the switch may be bad, heck its possible the switch itself may be bad.

i think theres some way to run a cable to engage the front axle to bypass all this vacuum garbage that fails time and time again. like i said i just started using vise grips cause i never knew if my 4x4 would work

we actually had a s10 come into the shop a few months ago where someone ran the vacuum lines in correctly somehow, they mixed up the vent hose and the vacuum line

 

I have the site for running a cable direct. The company that makes the kit is called posi-lock its about $200. You can due it way cheaper if you want but the posi-lock works.
http://diamond.site90.com/html/actuator.html
The cable he works with is junk this is the one posi works with.They also have all the correct hardware.
http://www.rustrepair.com/app2/onlin...ump-util.cable

I bagged the entire home made setup and went back to factory except for one thing.
After blowing a bridge rectifier on my alternator from running the truck with no battery to see if the actuator was working, I moved it. Placed it on the side of the fan shroud just like in diamonds conversion, had to get a new used braket after bending the one in the convertion.
It works great right there and you can always see what's going on. I would highly recomend it to anyone with one of these trucks.