front diff wont engage

Have a 90 Xj 4.0 4x4. When we engage 4x4 you can see the front drive line engage and spin yet the front axle doesnt seem to engage. Is there a vacume line that engages the front axle? What is there to trouble shoot?

Thanks for the help!

Bub

IIRC, a '90 should be a passenger side axle disconnect D30. Look on the passenger side of your front axle for a vacuum motor & shift fork assembly.

Perfect...Oil and junk clogged up the vacume line...Thanks...Pretty crappy design, what are the alternate options?

Depends on what you want to do. One of the [few] good things about the disco axles is that you can get 2wd-low without digging into the t-case. You can pull off the vacuum motor, and put in a posi-lock cable actuator. You can also pull out both passenger side shafts, add the right seal at the differential, and load in a non-disco passenger side axle to eliminate the disconnect completely.