Hi --I fixed one problem and soon after developed ã problem disengaging. 4wd goes into hi fast and smooth but when put back to 2wd its slow(30)sec and bumps like I hit a pothole. Ok before that the previous thing was a grinding when I hit 70mph,I would have to stop or put the 4wd on and it would be ok for awhile. Ok I replaced the vacuum switch and that fixed the grinding and now I've got that bump. I didn't have a bump till after the new switch, it disengaged fast and smooth, it also engaged good previously too___thanx in advance for any help---d

 

Could be the residual effects of having a vacuum switch that was apparently stuck open. Depending on how long you drove it with the griding, there could be some excess wear or damage to the 4WD engagement gears inside the front differential.

There's a great thread on another forum that shows what the 4WD engagement looks like from the inside. Also check out the YouTube video in this thread in the DIY section. If that spring is broken (pic here), might be hard for the actuator cable to return to the 2WD position.