after the last time I use 4x4, it clunked heavily into 4x4 , and clunked heavily again when it came out..... that was about a month ago, now it wont go into 4x4 at all.. is the 4x4 done with vacuum lines or is it electric?

 

Both, what year engine etc? Does the 4X4 light on the cluster light up when you turn the switch? Any other noises or symptoms? Is the "clunk" at the transfer case or front differential? Have you searched the forum for a similar problem?

 

its a 98 4.6l the light 4x4 light goes on.. I couldnt tell wher the clunk came from other, It didnt feel/sound like it came from under me, it sounded like it came further to the front of the vehicle... I did a search but didnt dig real deep into the responses..

 

I ended up changing the shifter solenoid on the front diff housing, it changes it to 4x4 and back, it was gone... pricey part $350.00 CAD.