Topic: 4wd not working

[89Redwrangler]

i took my jeep out to day...and when i went to engage my four wheel drive all i got was a clicking sound...my four wheel drive was not working at all...and thats not cool a 2wd jeep is like a four cylinder muscle car...

[Bounty Hunter]

Have you changed the transfer case fluid lately?  I'd drain it, watching the color of the fluid and for any debris.  Then replace with fresh. 

Also check the transfer case linkage to see if it needs adjusted. 

Did the 4wd light come on at all?

[goldenyj]

If it's a YJ, its probably a vacuum line, check the CAD (Central Axle Disconnect) on the passenger side of the front axle. Check the vacuum lines, I think there are 4 that eventually head back to the T-Case. Start with checking to make sure both ends are connected, if so then you will need to pull the lines and find your leak. Or you could just replace the whole crappy vacuum system with a cable, this can be done with a home made kit or the Posi-Lok (http://www.4x4posi-lok.com) kit.

[FourbangerYJ]

Ya, double check the vacuum lines. They are routed under the battery tray and sometimes battery acid can put pin holes in the lines. Also check at where the lines go into the axle.
If it turns out that the disconnect is messed up I have you can have. Just pay the shipping.

[Bounty Hunter]

A problem with the vacuum system would not explain the clicking sound.

[89Redwrangler]

am going to drain the fluid and check the lines this weekend...and i will get back to you....i hope it is just a line or the linkage

[goldenyj]

The clicking sound could be a number of things, really depends on where it is coming from. When you shift into 4WD it sends air pressure down the lines to engage the CAD, the clicking could just be it attempting to send air and failing, or it could be at the CAD, the diaphragm (or the air lines that feed it) that engages the collar could be damaged, this would prevent the collar from sliding over because of lack of pressure. Both sides of the axle and the collar are splined, if the splines aren't lining up this would cause a clicking.

[Bounty Hunter]

I've never heard a clicking from a disconnect, they will engage with the slightest pressure.  I run a cable disco now, and never get a clicking regardless of how slow the cable is engaged.

Clicking is most commonly related to the mode collar in the transfer case.

[Jeffy]

I've never heard a clicking from a disconnect, they will engage with the slightest pressure.  I run a cable disco now, and never get a clicking regardless of how slow the cable is engaged.

Clicking is most commonly related to the mode collar in the transfer case.

I have to agree that I too have never heard my disconnect.

I suggest marking the driveshaft with chalk and see if it's turning.  That will tell you if the transfer case is changing over.  You can disconnect the vacuum lines on the D30 to make sure the axle won't engage so you can isolate the noise issue.