2nd Gen Non-Engine/Transmission front axels won't lockup

[LDPetersen]

Yesterday I was pulling my gooseneck trailer , using 4wheel drive off and on all day. I pulled into my yard to park and it would not engage front wheels. Got stuck in snow and had to unhook. Found out today if I just tap on the shift motor assembly 0n the axel disconnect assembly , it will engage and operate normally. Has anyone had this? Is it low vacume pressure? Or that vacume motor itself??? Or something else in that assembly? Help. . Hard to get around up here in the north country with out 4 wheel drive.

Also found 1 bad u-joint, 150k miles on truck.

 

[mike r]

By what you describe you may have a moisture or rust problem in addition to a vacuum problem. If you tap it and it goes in its sticking and the vacuum is there. Something inside is preventing the movement momentarily. I've been up there and there's no shortage of cold and ice in the winter.

 

[DCorbett]

I had the same problem but mine was pushing the collar over far enough to edge of the other axle and it sounded like was about to blow. I took it to the dealer and they tore into the motor on the axle and showed me everything was ok, it must have stuck. I asked about the vac. and he took it off and tested it and it was fine. I did ask if there was anyway of knowing if the vac. pump was going out and he said it also runs the motor that runs your defrost and it will only blow through the vents if it is'nt working. but I'm like you I use my 4x4 all the time and I'm sure it gets oiled from use. Hope this helps

Doug

 

[LDPetersen]

forgot to mention this is a 95' 2500. ext cab. has never shown any problem with this before. Seems odd that it never failed before and seema sticky now. Any idea how much these vacume motors cost? Thanks for the help. Anyone else got ideas?

 

[DDT]

I had trouble with mine. The dealer put a new swtich on top of the transfer case, did not help. another shop unhooked vacume lines and blow them out with compressed air. worked for me.

 

[datablitz]

mine failed also, replaced the vacuum device on the axle. also replaced the fork for good measure (which didnt need replaced IMHO) but my CSC picked it up...

 

[vssman]

I've also been having problems engaging the front axle and also have cleaned the oil out if the lines. One thing I noticed was that the main vacuum line near the pump was oil soaked and soft causing it to collapse. It appears I had enough vacuum for the brakes and heat but not enough for the front diff motor to engage.

 

[LDPetersen]

I just stopped by Dodge dealer where I bought the truck . Small town dealer , parts man said he sold 12 switches for transfer case last year , only 1 vacume motor. $209. 00 for motor. That seems to be my problem but I want to be sure. Think I will do somemore testing. Has warmed back up to 20 degrees today. I guess I'll crawl under it tonight. Thanks. I'll update if I find it for sure.