I have a 2000 Ford F-150 with shift on the fly 4WD. Was recently pulling a boat out of a steep ramp and had to put it in 4WD. As I was pulling up the ramp I herd a pop and 4WD disengaged. Turnes switch back to 2wd and them back to 4wd and continued to pull. Now when you go to put it into 4wd sometimes it will engage and sometimes it will not.

Would like to know if anyone had any suggestions on what could be causeing this. Like I stated sometimes it will work and sometimes it won't.

Thank's in advanced

 

I would start by taking a look at the vacuum actuator on the front axle. Clean and lube it. It could be "cruddy" and not engage all the way.

 

Thank's for the reply. I took the actuator off and cleaned and oiled it but I am still having the same problem. I think the next thing is going to take a look at the hubs.

Thank's

 

There is no lockout hubs on these series trucks. I would have someone work the switch while you watch the vacumn actuator and see if it moves.
Rich

 

thats right, hubs are always locked to the alxe shafts. When you turn the ****, you engage the drive shaft electrically at the transfer case, and by vacuum piston at the front pumpkin. make sure it pulls in all the way as 96' said.

 

--alos, this "shift on the fly" dont always work. I always do it from a dead stop. put it in 4 x 4, then shift to neutral, or backup a foot, then forward, etc. Make sure the engage light is on and you hear it clunk into gear.