2002 f250....Ok now trying to figure out this four wheel drive. Replaced the hubs today. Still nothing!! Front drive shaft is turning while in four wheel drive. Hubs will not lock. Vacuum pump is running then shutting off. I'm thinking vacuum hub lock selinoid is bad. Not getting suction at wheel. These are auto locking hubs. Need your advice.

 

do they turn when u Manuel lock them in?

 

Ok this is what I don't get. I've been told these hubs can turn. I don't know how. The one that are on this truck have no writing. They have one white stripe going down the center. They look like there manual locking hubs but there plastic and I belive they'll break if I put pliers on them and a little pressure. Am I wrong??

 

My hubs won't engage by the switch on the dash, I have leaking seals and haven't gotten around to fixing them yet. I pulled off both vacuum hoses where they attached to the hubs. I plugged one and put my mityvac on the other. When I turn my switch in the cab I get the correct vacuum levels. Therefore my pump and silenoid are fine. Here is a page with some good info on it Welcome to guzzle's 4x4 Needle Bearing Maintenance Web Page

 

Great link right there...

Your hubs have an auto setting and an auto setting. Turning them will make them manual.

More then likely its the hubs, nothing else.