I have a 97 F-150 four wheel drive pickup. I do not have manual front hubs. When I switch to four wheel drive high, other than the 4x4 light comes on, my front hubs do not engage. When switched to four wheel drive low lock the light comes on, the differential engages but the front hubs do not. What is the problem?

 

Hi Tony, welcome to FTE!

You posted in the Super Duty forum, which isn't the best place to get help with your problem. I've split your post off into its own thread in the '97-'03 F150 forum, the folks down here will be better able to help you out.

Now as for your issue, your truck doesn't have hubs that lock or unlock. The front axle shafts are permanently connected to the hub, so they are always engaged. There is a disconnect at the differential, but I don't remember the specifics of how it works. Hope someone here can give you some better suggestions.

 

two things happen when you go into 4 x 4... first is the electric motor on the transfer case engages either LO or HI to the front drive shaft. You get a light that says if you are in L or H... second thing is a vacuum cylinder on the differential pulls an arm and engages the driveshaft to the front axles half shafts inside the pumpkin ... it is not uncommon for the arm on the vacuum cylinder to bind up with rust / crud. Look under the truck at the differential. Look for two vacuum lines on the cylinder. Pull htem off and feel vacucm on one when in 4 x 4 and on the other when not in 4 x 4.. If you have vacuum, then tap on the vacuum cylinder and arm / spray with lube / retest.

 

I will check that in the morning thank you

 

Hi Tony I had the same problem with mine, mine is a 98 f150, what I did was jack up the truck engine not running with the key on turn the **** to 4x4 try to turn the drive shaft going to the front diff if it wont turn then your transfer case is engaged, if it is then do like Steve said check for vacuum, my problem was broken vacuum lines going to the black solenoid. There's two elec switches on the upper right corner under the hood, mine had a blue and a red vacuum line the red line just rotted, I went to napa and got the smallest line they had i ran new line and used red elec fazing tape just to mark the line. The new line will be clear. I hope this helps.

 

Ok I have vacuum at the electric switches but do not at the vacuum cylinder. I have no movement of the wheel hub engagement lever in any position.

 

Tony those switches are elec, with the engine running you should have vacuum going into the switch, with the switch engaged the other line should have vacuum on it if you do follow those vacuum lines down they go to a rubber block, mine was broke just before the rubber block.

 

If the two electric solenoids are working, I think you will have one hose with vacuum all the time. When you switch to 4 x 4, the solenoids switch and you will have vacuum on the opposite hose at the vacuum cylinder on the axle pumpkin.

 

It seems to me the hoses run toward the passenger finder, then down the inner fender, under the motor to the axle.... I think there is a connector on the hoses on the passenger fender well. I remember pulling this apart one time by accident when I was working on the passenger wheel hub ABS wire.

 

Steve you are correct, that's were mine was broke, it was weird how the plastic hose or lone just rotted. Napa had that small hose or line.