Hello,

(2004 f150 S.Crew 4x4) I noticed that my 4 wheel drive is not working. The front hubs won't lock in. The transfer case will go into 4 low but the hubs still won't lock in.

Anyway, I have pulled vacuum on both actuators and one of them won't hold. It's obviously bad, but is that why I don't have 4x4? It seems to me like it is not...

When I pull a vacuum on the actuator that does hold, it disengages the hub from the driveshaft allowing free-wheeling. Correct me if I'm wrong, but when the truck is running in 2wd, vacuum must flow to the actuators preventing the hubs from engaging? The actuator on the bad side is locked 'in' so the driveshaft always turns.

According to my train of thought, since the actuator has failed in the 'locked in' position, I should still have 4x4- What am I missing?

thanks -jim

 

Update- I'm a bit of a bonehead... I had replaced one front hub a year ago(That also happens to be the side with the good actuator). Then, when I was having 4x4 issues and was thinking the actuator was the culprit, I bought a hub for the other side, thinking the actuator was part of the hub. When I pulled things apart this morning, I finally figured out they are separate parts -yep, bonehead!!

So, I put the new hub on and replaced the lower steering column shaft as well. I took it out for a spin, mainly to test out the steering, but thought I'd try the 4x4 again while I was at it. This time it locked in and 4x4 worked!!

Any thoughts as to why? (260xxx miles)

 

I'm not an expert on these systems, but I remember that when they fail they can grind themselves up when they try to engage while you're driving down the road. I'd think that your actuator failed slowly that permitted the IWE to engage your hub on and off while going down the road and ended up chewing up the splines.

Just a WAG, but it would make sense. Can you post pics of the old hub?