Ever since I bought my truck the 4x4 has taken forever to enagage and finally it just gave out (while off roading...go figure), the 4x4 light comes on but the front wheels wont engage, I'm thinking my Vaccum actuator may be out because it slowly died. Any Idea's?

Btw, its a 91 S10 Blazer.

Thanks.

Chris

 

Other possibilities are vacuum lines to and from the switch on top of the transfer case (or the switch itself could be cracked), could be a line is cracked with age and leaking. if you have a vacuum pump with a guage put it on the actuator, pump it, and see if it moves - it may not engage fully without wiggling the truck - then see if it holds the vacuum for a few minutes. If it holds the vacuum then the hunt begins for the leak

 

The switch on the transfer case is a PITA to get to, have patience it can be done just tight quarters to work in.....If the front vacuum actuator is bad just get a POSI LOK, the failure rate of the vacuum system is high with these ones, might as well spend the 100 bucks and get a permanent solution....but you do have 2L now and will have it with the POSI LOK as well unlike with the vacuum system, just food for thought.