'85 s15 jimmy front diff prob

[gearhead_v8]

Hi I have an '85 s15 jimmy that pissing me off, my front hubs are not locking in, and have been looking on the forums but can't find anybody who has the same year rig. T-case shifts fine and when in 4wd the front drive line locks up but won't turn my front wheels. Any help would awsome

[BlazerLT]

Check the 4wd shift linkage for play.

[gearhead_v8]

I'll check it but it seems to be fine like i said the rear wheels gear down but the front hubs dont lock. I also checked my vacuum lines it doesn't seem to have any vacuum.

[blazes9395]

The front differential is vaccum operated, its usually something to do with some part of the system. If the light for the front differential is not lighting up, there are a few things that you can look at thats fairly common. There is a vaccum operated switch located on top of the transfer case that three vaccum lines are connected too. This switch is opened when transfer case is put in 4x4 to allow vaccum to engage the front differential. I really don't remember which side its on, I think its on the passenger side, but on top of the transfer case. Follow the three vaccum lines and you will find it. Take it off and check it, there is like a steel ball that is suppose to move freely when you press on it, if it doesn't its not working right, replace it. Its a good idea to locate the vaccum line(s) and check their condition to and from the transfer case and the shift linkage, to make sore they are not just wornout. Hope this helps