I just bought a Chevy S10 Pickup...the truck was pretty banged up, one of the problems being the 4wheel drive not working. The button for 4wheel hi is lit but jacking it up... only the back wheels and drive shaft spun. Pushing any of the 3 buttons seems to do nothing.

I started poking around, and found some badly rotted vac lines going to the transfer case/back of tranny. Is the 4wheel drive engaged with air pressure? Not familiar with this kind of system, maybe someone can enlighten me. I cut out the bad parts and replaced with new lines, also notice a bit of oil dripping from one of them.

Started it up, the truck seems to be running very funny, actuallystalled out on its own once. Maybe the previous owner raised the idle to compensate for the vac loss, butI dont really know. Tryed playing with the buttons... now when I push 2wheel hi or 4wheel hi, I get a loud knocking sound coming from the transfer case, and the shaft coming from the transfercase is spinning.

Anyone have any input on what to do, or what might be the problem? Last resort, I take it to a dealer to get fixed.

 

You need to invest in a shop manual if you want to diagnos and fix your truck yourself. The dealer will drop a huge bill on you for just to look at it. Even a Chilton Manual will help a lot. Also you can find manuals at a good public library for reading and reference.

I just joined this forum, but right away I noticed most of the Posts have zero replies. I don't think we will get a lot of help here.

Replacing those vacuum lines will help something. And if you are lucky, may fix your problem.