ebrant said:
Yesterday, I managed to get my new (to me) '99 250 Super Duty 4x4 stuck. In the process of getting it unstuck, I was shown that I need to manually lock my front hubs to engage my 4 wheel drive. According to my owners' manual, operating the vacuum switch on the dash is all I need to do. So, my question is: which is correct? And is my 4x4 switching mechanism defective? Broken vacuum line? or what? Thanks to all you more experienced off-roaders.
My guess is that you have bad vacuum lines to your hubs. Thank goodness that Ford supplied mannual override locking hubs on your truck, huh?
The vacuum lines to the hubs are not an uncommon fix. They go bad quite often. One way to check (but is not a tell-all diagnosis) is to see if the air control in the dashboard goes to default (which is defrost, if memory serves) no matter what setting you have it on, as soon as you switch on 4x4. The lack of vacuum (which controls the air direction settings) causes the dohickey to go to default setting. Just crank up the fan, set it to blow out on the floor, and turn on 4x4. If you suddenly have air coming out the defrost vents, then you are 100% sure.
But, like I said, this is not a 100% proof postive diagnosis tool. You can still have bad lines and not affect air control...
