1997 Ford F-150

Drive Train Axles Bearings problem
1997 Ford F150 V8 Four Wheel Drive Automatic 97,800 miles

A while ago my 4wd would only work sometimes. Now it doesn't work at all. I found out that there is an actuator that you can zip tie down when you need to put it in 4wd. I think the problem is that the hubs won't lock, because they're vacuum actuated. Do you think I have a vacuum leak somewhere that might be causing this? Would it be hard to install manual locking hubs?
July 20, 2010.

It could be either of the two. If you have electric shift 4wd, start by checking if the actuator on the transfer case is getting power. If it is, remove the actuator and confirm that it is working. If that is okay, then you most likely have a vacuum leak to the front axle.

Check that and let me know what you find.

The actuator is working. If it is depressed after I use the switch to engage the 4wd then the 4wd does work.

Jul 20, 2010.
Check for vacuum leaks at the front axle. If the actuator is good, then the axle must not be engaging.