A few weeks ago my '05 F350 diesel overheated because the bottom hose on the radiator came off for some reason while on the ranch. When I found out about this I got distracted after unlocking the driver's side hub but forgot to unlock the passenger side hub which stayed locked until I drove it home from the repair shop. The overheating took out the EGR cooler and the oil cooler needed replacing by then anyway. I'd driven about 30 miles, most of it at highway speeds with this hub locked and I was wondering if I'd screwed something up in the front axle. We were working on a windmill in the pasture this past week and the back tires began to spin in the cactus but the front tires didn't seem to do anything even though the hubs were both in the locked position. My truck is a King Ranch which has no internal shift stick to engage the front drive wheels so I assume it's always engaged and the hubs are what lock and unlock. The vacuum engagement on the dash has not worked in a long time due to the vacuum lines being worn through in a few places so I've just been locking the hubs manually. Could I have really messed something up in the front axle? There's been no unusual noises up front, no smell of anything burning.

 

 

Oh sure, the dial is on the dash and the light comes on when I turn it to any of the 4WD settings but I found that, when I do and the A/C is on, the air shifts to the defrost vents without me touching the A/C controls which I found out was an indication that the vacuum lines going to the hubs were compromised in some way. When I changed out the starter last year I found that the point where the lines T-off to go to either hub had become oil soaked and the rubber that the tee is made of became too soft to keep the vacuum. Haven't had time to replace the lines as yet so I've just been locking the hubs manually when I go into and out of the ranch.

What I meant was that other trucks I've seen pictures of have a floor shift lever for engaging the 4WD which is not what's in my truck.

 

The dial on the dash does two things when you turn it to 4Hi or 4Lo. The first, as you noted is to lock the hubs using the vacuum, which is obviously not working on your truck. The second thing that it does is send a signal to your transfer case shift motor to change the position of the transfer case gears (much like the floor mounted lever does in a manual system) to engage the front drive shaft from the transfer case. As such, you still need to turn the dial on the dash to 4Hi or 4Lo to get 4 wheel drive, even with your hubs manually locked. If you turned the dial, and the light came on the dash, but still didn't have 4wd, then you need to verify that the transfer case shift motor is working properly.

 

 

 

DJ hit the nail on the head - the dash mounted switch is designed to perform multiple functions. It is supposed to lock the front hubs, however you can by pass that function by manually locking the hubs. The second function, which it sounds like is your problem, is that it also activates the transfer case shift motor. You can manually lock the front hubs, but you need the transfer case shift motor to engage and move the transfer case from 2wd to 4 hi or 4lo. The transfer case shift motor is controlled by the dash switch.

Finally, no you should not have done any damage by driving with just one hub engaged.

Please keep us posted

 

Oh great... So this means I've NOT been running around in 4WD even though the hubs are locked? The truck's user manual is really clear as mud about this. I had to read the section on manually locking the hubs several times and finally just flipped the hubs and went on. Well, at least the front axle was probably just free wheeling when I had it locked at 75. Also I'm either going to have to plug off the vacuum lines or spend some more money on getting the line replaced in order to keep the A/C from flipping up to defrost when I engage the 4WD on the dash. The last time I looked on the official Ford parts site the lines were sold as a unit and not in pieces such as the tee. This is very much a weak point on the truck. I'll flip the dash switch AND lock the hubs the next time I'm on the ranch and see what happens. Not running the A/C much right now.

Thanks for the education!

 

Correct, locking the front hubs JUST locks the front hubs. So, when you drive the front axle halfs AND driveshaft are spinning because the front tires are turning them.
You MUST engage the transfer case to provide POWER to the front driveshaft/axle/wheels.
You MUST turn your dash ESOF dial to 4hi or 4lo.
There are easy write-ups how to find/plug your vacuum leak..

You can easily plug the vacuum line at the hub(s) - IF that is where the leak is..
Then you continue to manually lock/unlock the hubs, AND use the ESOF to engage/disengage 4wd.
I have manual 4x4 - the short shifter on the floor, because I wanted to avoid ESOF issues.
I leave my hubs locked all winter, no issues at highway speeds - OTHER than reduced MPG from added drag..

 

We bought the truck used and, this being a totally new type of vehicle for us, we were pretty much ignorant of many of its characteristics. The main thing I was worried about was the 6.0L engine I'd heard mixed reviews about.

I know where one leak is and if I can seal that tee with some kind of silicone or other sealer that sets up in the presence of oil it may take care of that problem. Bouncing across the pasture, though, has kept me hopping with all the problems it has produced. I think what I really need is an Abrams tank but it doesn't have much carrying capacity and would upset a lot of people at the feed store.

 

The Abrams would be overkill. Tryfinding a M114 or a M113. If you need cargo capacity find a M35.

 

I'll have to write that down. It'll be my first shopping trip after I win the lottery. LOL. There used to be nothing but other ranches surrounding us out here in the sticks but now we've got real estate developments springing up on our North end. It'd be so much fun to have a tank patrolling that area instead of a bunch of wimpy "No Trespassing" signs. I could hang the sign off the end of the barrel!

Well, now we've really gone off the path here!