I've been working on little Bro's clapped out ranch truck and am currently fighting the 4whl drive. When he bought it some of the vacuum lines were disconnected and I felt sure that was the reason the front would not engage.

Well after hooking everything up (his is a 95 like mine) using mine as a guide, and then clearing the stopped up lines, still no vacuum to the axel. I've got vacuum to the vacuum switch on the transfer case, but only to the one port that is direct form the vacuum pump. I've pulled the switch and made sure all 4 ports are clear, still nothing.

So, has anyone ever heard of one of these going bad?

I'd pull mine but the frame mounted air tank makes access to mine a fairly big job what with rhw R&R of the tank and all, I can do it, would just take a while.

Thanks, RJR

 

I haven't had one of these apart but you said the lines were stoped up, maybe what ever got in the lines got into the switch remove his and see if you can clean it out and opperate it manualy and get it to pass vacume if not my guess you'll need a new one, also run a vacume line straight to axil and see if it will work that way sometimes that will get stuck also.

 

John, thanks for the relpy. It now seems that the rubber plug that connects to the vacuum switch is the culprit. After years of being oil soaked, it has swelled and will not seal to the male outlets of the switch.

Tomorrow I'll see if the plug is available.

RJR

 

If that doesn't solve it you could buy a 4x4 posi-loc. It replaces the vacum parts on the front axle with just a cable that runs into the cab. It's about 200 bucks I think, I had one on my Jeep, it uses the same setup, and it worked perfect.