I have a 2004 F350 with 6.0. My problem is the 4x4 will not engage from inside the truck. I have to get out and twist each hub to lock in the 4 wheel drive.
If I rev the engine with high rpms the front will lock in with a big jerk. It use to lock in just by turning switch.

Has anyone ever had this problem? If so what is the best way to fix it?

Thanks
Alton

 

you have a vacuum leak in one of the hoses feeding the hubs.

 

5

I'm agreeing

 

Could also have a failed auto hub solenoid. It is located behind the passenger battery. You can test it by engaging the 4x4 and testing the vacuum on the other side of the solenoid. I just replaced mine last week.

 

Look up Diesel Tech Ron on YouTube. He has a video about how to diagnose the problem and how to easily fix it.

 

I would lean closer to having a failed hub seal. Put a vacuum tester on the hub nipple and pressurize (Vacuum) to 15 psi, if it doesn't hold or even get there, your hub seal is gone and no amount of checking the lines will get you anywhere