More 4wd Problems

After I replaced the vacuum line going to the actuator I thought I had it fixed because the indicator light showed that the 4wd was working correctly. After some offroading I discovered the front wheels werent rotating at all right as I was about to get stuck in some mud.

A couple of times when I have put it into 4wd I have also heard a loud grinding noise but then it goes away after I take it out and put it back into 4wd (its a rare occurence)

Since it seems like everything has to do with the vacuum lines. Where are all of the locations where the vacuum lines connected?

In this case, I would make sure the front diff is actually working, and you have no bad CV joints or anything like that. Take the cable off the actuator under the tray, and manually pull the cable to engage it. After I pull the cable I use vise grips to hold the cable in the engaged position.Tak it for a spin, if your 4x4 is now working, front diff is o.k. and now you can know for sure you actually have a vacuum problem/no engagement. If its a CPI engine, the vacuum hose is loacted at the back of the intake, on the passenger side. It could be a split line, feeding other things too, but if you trace it up, its there.