Checking 4x4

[TWeatherford]

Guys, I'm looking for a truck. One thought I had was how to verify that the 4x4 works in my pre purchase inspection. Of course I could take it to a nearby hill and start backing up it, rear wheels should break loose real fast if it isn't working. Of course if only one of the front wheels is turning (which I've seen happening) I might not be able to tell. Probably will be looking at it alone.

Could I just jack up the wheel in question, with it in gear (I'm only interested in a manual transmission truck) and verify that it doesn't spin with the hubs engaged? Or would this not be a very good test? I have a basic understanding of how the hubs work, seems like either they'll grab or they won't.

Of course then I've got to inspect every other system on the truck... might make myself a checklist. Of course these old IDI's seem to all have some character to them, thats ok I just don't want too much.

 

[02AutoWag]

This is the response I got from the same question:
http://www.oilburners.net/forums/showthread.php?t=25140&highlight=inspection

 

[k_williams1982]

I have always checked by engaging the transfer case on trying to spin the front driveshaft. If it "locks" and won't turn, then I know the transfer case is engaging. Next, I put the transfer case back into 2 wheel and verify that the front driveline turns freely (transfer case is disengaging). Then I lock in the hubs and again check the driveshaft to make sure that it doesn't spin with the hubs engaged. This method will only work with manual hubs, and does leave the possibility that something may still be wrong. The best way to accuallytest the 4 wheel drive is to use it.

 

[Shadetreemechanic]

I just find a gravel parking lot, give it hell in 2wd and then try the same thing in 4wd. You should notice a big difference in how you take off.