Engine/Transmission (1994 - 1998) 4X4 not working

[24valver]

I think I've narrowed my problem to either not enough vaccum, or the shift mechanism on the front axle isn't working. I put a hand vaccum pump in the front axle and I could hear the shifter click, so that should be ok right? I traced the vaccum lines back to the transfer case, but I don't know where they go from there. What should I check next?

 

[Bloomy]

It's a fairly common problem with the CAD. A few years of grime and other things can cause them to stick. You can take it apart and clean it and it should still work. The better choice is to spend a little money on the cable actuated system and dump the vacuum system.



Thomas

 

[bighammer]

Could be the vaccuum switch on the top of the transfer case.

I have a push/pull pneumatic switch that was said to be a liftgate control. I run the vac supply to it and then the 2 lines to the front axle. (no more control by the transfer case)

 

[AndyJohnson]

I have worked on one 99 that in 120 k went through two shift collars and one axle shaft on the front actuator. Keep in mind it was abused hard like while spinning hard dropping into 4wd. Also like bighammer said i have replaced several of the vaccum switches on them also it is a common problem that your local dealership should stock for about $25

 

[KingS]

Mine did that last winter you could hear click but never would lock so I took it apart cleaned it moved back and forth fine so put it on still wouldn't work took it off again and looked allittle closer at it and the rod the fork sits on was bent just allittle just enough to not let it slide over all the way with the pressure of the gear on it bought a new one perfect ever since.

 

[CumminsPower98]

My cousin's '97 has had some oil leaks which have softened the rubber manifold that plugs onto the switch at the transfer case so it leaks bad enough there to keep the axle from engaging. Just something to check.

 

[24valver]

Thanks for all the replies! I ordered the vaccum switch from my dealer; it was only $19. 25 and should be in Tuesday. I'll keep y'all posted.

 

[JWashburn]

One more place to look. When I put in the 3K GSK through the side I inadvertently pulled a vacuum line out of its connection. Had 4WD before but not after the install. I discovered the disconnect and got 4WD back.



The line runs from a connection at the very top of the firewall pretty much straight up from the fuel fileter. It then connects to a rubber elbow near the front of the engine below the P7100. Its about 1/8" od and hard plastic.

 

[24valver]

Well, the problem continues but this time I found the problem. When I was replacing the transfer case switch, I found that the vacuum line from the manifold to the transfer case was gone. So I assume a plain rubber line is what should be there. Also, what size is the line and how long should it be? Thanks

 

[24valver]

Does anyone out there know what size and the length of the rubber line from the manifold to the transfer case?

 

[Got Smoke?]

I chased vaccum probs for nearly a year before finally purchasing the Posi-Lok cable kit on Ebay. The posi-lok is a little more aggervating as you have to roll the truck forward a little bit while getting it to engage sometimes, but its woth it for positive engagement EVERY time.



Wish I had a grand to blow on the lockout hub conversion. :{ :-laf