My F150 will not go into 4 wheel drive. When I shift into 4HI the light on the dash turns on and the shifter feels like it engages. The front drive shaft does engage and start to rotate, however the front tires do not engage. The truck has automatic locking front hubs, when the front drive shaft is rotating there is no rotation of either front drive axel going to the tires.

With the truck off and not in 4 wheel drive I can spin the front drive shaft by hand and I can listen to the hubs lock and the front passanger tire will rotate (drivers side sounds like the hub locks in and jumps right back out, does not rotate tire).

Any help with this issue would be appreciated. Not really sure where to go from here.

 

Personally dump the auto locks and put a good set of manual locks. The auto lockers are junk that break all the time.

 

Turn your hubs to lock or manually lock them. Im not very familiar with these "older trucks" no offense not sayin your truck is old, just older. If the tires do spin in manual lock then u probably have a vacuum leak somewhere not letting vacuum reach the hubs.

 

Do the auto lock hubs not have a selection to manually lock them? like i said in previous post not too familiar with these trucks...

 

As far as I know there is no way to manually lock the auto hubs.

 

No no way to manually lock auto hubs. A manual set like warns premiums. And there is no vacuum to these trucks. That is the newer ones that have vacuum and manual hubs.

 

So how do these hubs work with out vacuum? I might have to research a little, sounds interestin

 

The auto hubs I dunno I imagine they have a racheting mechanism that catches when you go forward or backwards. I know that if you go forward and then backwards they unlock for a bit. I have seen people break them just going thru paster land. I always have used manual lock out hubs.

 

springs and inertia are how the older ones work, the axle starts to spin and it kicks out, the spring keeps it enguaged untill you have it in reverse and travel 5-10 feet backwards. also known to be inherantly junk.

the newer ones operate with a vacume signal or a manual turn that leaves them fully locked until you turn and unlock them, much better design than the 1st autolocks.



as for your issue you can take the autolocks apart and clean/inspect them and pending that grease and reinstall them. they work ok if you keep them clean and lightly greased but definatly worth it to remove and replace with manual hubs. that way there is no guessing, its either enguaged or not.

 

hmm another thought, have you tried putting the truck up and enguaging 4h? wonder if there is a problem with the front diff? at any rate start with the hubs and go from there.

 

I had tired cleaning and regreasing the hubs, Passanger side seemed to move more and be more free after cleaning than the drivers side.

Put them back on and tried them, still didn't lock in. Either didn't clean them well enough or there is something else wrong. (going to try and clean them up and re-grease tonight).

As for putting it up on jack stands I had all 4 wheels up off of the ground and when engaging 4h did not see any rotation of the front wheels. I did see the front drive shaft rotating however there was no rotation of either front axel going to the tires.

Not sure what the truck is suppose to do while engaged on jacks (since automatics should rely on spring tension, I don't know if they would engage without any tire friction).

 

Well I think I figured it out, While tearing apart the driver's side hub again I noticed that the washer seemed to be loose (previously I had not gone that deep). It seems that some how the outer nut loosened up somehow causing the washer to slip off of the peg of the rear nut. After tightening everything back up and driving the crap out of the truck for awhile I now have my 4x4 back.

Still not sure how everything works exactly but it seems to be working now.

Thanks for everyone's input.