I have a '97 F150 4x4 w/o SOF. I am having a problem engaging 4WD. I placed the truck up on jackstands and I have checked the following while the truck was running: The front driveshaft is turning, the vacuum motor is pulling the actuator rod in as far as it goes, the rod is spinng the shaft that enters the top of the Diff so the roll pin is good. The problem is the front wheels do not get any power.
One other symptom is when engaging 4WD when moving there is a sound like a sprag is not engaging, similar to putting an auto trans in park while still rolling except nowhere near as loud. When I roll to a stop there is a sound like this sprag engages, yet the front front wheels still are not powered.
Broken spider gears or some sort of actuator inside the front diff?
Any Ideas????
Thanks,
Tom