2001 kia sportage 4x4 problem

I just replaced the vac. lines to my front hubs and now the hubs are now starting to engage and disengage while still in 2H. Could this be that I have a bad hub?:mad:

.. mine was like that when I bought it too. THe vacuum solenoid valve was stuck partly opened, probably from injested dirt....I removed the valve and cured it by injecting WD 40 through the ports, then acting the solenoid with 12V on and off, and blowing through the ports. This brought it back to normal operation.
http://www.geocities.com/lmp4203/kiasport/vacsol.jpg
...but eventually, I had to change the hubs for Warn automechanical 61918 because the original vacuum were not able to cope with winter cold.
ALso, some KIA service used to reverse the spring position in the vacuum hubs to keep them ON all the time since the vacuum action was unreliable. Just test that by trying to turn the front driving shaft with engine not running and Tcase in 2H. It should turn freely.

LMP thanks for the fix tip.... my 4WD vacuum solenoid gives 15 inches vacuum engaged, and 5 inches vacuum in 2WD... looks like a leaking vacuum valve (solenoid). I will try your fix before replacing it (it seems to be a dealer only item).