02 F150 4x4, front end sounded engaged, visual check confirmed that when spinning front wheels driveshaft back to transfer case spun, assumed vacumn thing on front diiff. wasn't shifting fork on diff. manually shifted but still have front end noise. Is the cv type axle coming from the hub to the diff. supposed to spin when front diff. isn't engaged? Are the hubs supposed to unlock from the axle/cv shaft like the older style drive shaft with manual lockers? Thanks for any advice/input.

 

my cv axles spin when i spin the wheel and i'm in 2wd.

 

The only disconnect is at the t-case. The shaft, axles and cv's spin with the wheels.

 

the **** on the dash chooses 2wd, 4h or 4L. that is selecting inside the transfer case and engaging the front end. at the same time, a vacuum cylinder pushes a rod into the front differential housing and engages the front end. So when you are in the driveway parked in 2wd, you can crawl under the truck and turn the front drive shaft by hand. nothing else will turn. If you put the truck in 4wd, you engage the drive shaft at the transfer case, and engage the axle with the vacuum cylinder. The differential is connected to the CV and the front hubs all the time.

 

Unless the **** on your dash reads 4AWD 4H 4L, then there is not a vac system on the diff. Might be an Expedition thing. I can't turn the driveshaft on the Expy, I can on the same year F150 with the 2H 4H 4L switch.

 

i have a 2001 4 x 4 F150 and there is definitly a vacuum cylinder that engages the front axle. with it in 2 wd, you can rotate the drive shaft and neither the wheels or the transmission moves.