I have a 85 dodge w150 that the four wheel drive stopped working all of a sudden. It worked fine when I used it last winter and the last time that I went to use it, it wouldn't go in. Being that it worked fine and then just stopped for no reason the only thing that I can think is that the vacuum actuator on the axle went bad. It has warn manual lockout hubs and I can watch the axle shafts engage and disengage when I lock the hubs and the transfer case shifts fine through all of the ranges. Is there a way to test the actuator or any other ideas?

It may have lost it's vacuum signal, and you can put a long vac hose or a hand pump on each of the vac nipples on the axle servo and it should engage on one, then disengage when you switch hose to the other one.

The vacuum switch on top of the transfer case, likes to stick. You can turn it out, and see if the ball plunger is stuck up. It usually is, from not being used. OR you may have a broken vacuum line going to the switch on top of transfer case, or going to the front axle actuator.....

Just wondering if you got it fixed??

Yep, mine failed on me last winter. Turned out to be the large 4 port plug on top of the t-case was all dry rotted & sucking air. They are not available from the Stealership or aftermarket. I had to make a schematic as to which hose went where, eliminate the plug & install all four lines individually back onto the t-case switch. It has been working flawlessly since.

My '85 went bad also (had Warn hubs also). IIRC, there was a write-up on RamchargerCentral.com about R&Ring the actuator, sliding the collar over, and reinstalling the actuator so it stays engaged all the time.

Edit: Found mention of it here-

http://ramchargercentral.com/vehicle-help/cad-pictures-and-links-to-the-faq/

HTH

Tim

I used a good citrus cleaner on the vacum switch on the T case soak it for about in hour then do some very light vac test. should take care of the problem.