Fords design on their F series trucks 4WD. I seem to have the same issues as everyone else does concerning the 4wd. Lets just say their is no vacume, cause I took that junk out. When I engaged the ESOF the light on the inside comes on like it should, I here the transfer case ingage, but only get rear action. I manually locked the hubs but still have nothing. I looked underneath and the front driveshaft was turning. Is the drivetrain suppose to turn regardless if 4x4 is engaged or not? Cause it turns regardless if its in 4 or not, locked or not.?? Suggestions?

 

OK, first lets go over what happens when you turn the switch from 2H to 4H or 4L on your truck.

To start with a vacuum solenoid sends a pulse to the front hubs, which accuates a cam and locks the front hubs. A lot of things can go wrong in this process. Common problems are leaking vacuum lines, a bad vacuum solenoid, bad seals on the hubs and bad hubs. If your front driveshaft turns while the hubs should be in freewheel mode, chances are very good you have a bad hub. While you may see some drag when the hubs are unlocked (which will cause the driveshaft to rotate) you should be able to reach behind the wheel and rotate the axle with your hand when the hubs are unlocked. If you can't you probably need to replace one or both hubs. I would recommend replacing them as a set.

OK, while the hubs are being locked, a signal is sent to an electric motor on the side of your transfer case. This motor turns a shift on the transfer case, which shifts the transfer case into the range you selected. 2H, 4H or 4L. These electric motors can also fail, but new shift motors are readily available at most neighborhood auto parts stores.

 

Well, it turns freely. Thanks. About the vacume... I had the pulse solinoid frying out due to the air canister not holding a seal, would you believe I went through 3 of them, none would hold a seal. Wasn't getting defrost inside the cab, after pulling the heat box, yada yada, removed a bolt that seemed to be holding the door open. Thats when I trashed the canister, got a new solinoid and straight wired the lines running to my heater. The lines going to the hubs where not working anyway so I plugged them awhile back, but thought if I manually locked the hubs, I would have the front wheels turnning.
So, a new set of hubs seems to be the likely fix?

 

If you are going manual anyway, I would replace the stock hubs with a set of Warn or MM hubs.

 

Thanks very much. It's been bugging me since I got stuck in my front yard the other day. "flat yard with grass"

 

Now you know the reason I don't have the ESOF system on my truck. Yes, I have to get out and lock the hubs and actually pull on the lever, but I know it will be there when I need it. I just make sure the hubs are locked before I leave the house if I think there may be a chance of using 4WD.