I have a 07 F250 four door 6.0. The four wheel dive in auto does not engage the front tires. But when u manually turn the hubs into 4x4 she engages. What's the problem in the auto mode ????

 

bad hubs, or vacuum leak.

 

Yup.............

 

x 2 .

 

I'd say vac leak more so than bad hubs.

 

How and or where do I check for this Vaccum Leak ?

 

the easiest way to see if it is a vacuum leak is turn the ac on and go for a drive. if air only comes out of the defrosters it is a vacuum leak. if all ac/heat functions work as they should, it is bad hubs.

 

the normal vacuum leak point for auto hubs in at the vacuum hose nipple on the back of the front wheel.

 

Wait, it's a diesel, does your heater switch over to the vents or is that stuck on defrost?


If its stuck on defrost, it's your Vaccum pump. If not, start at the hub, fallow the vac line off the top of the knuckle, and see if one side is broke. Fallow that up to the selonoid. That could be shot too. But I'd think most likely, it's the seal inside the knuckle. That seals the axle shaft to the knuckle. Or possibly the diaphagm in the lockout hub itself.

 

Tom, it will only turn to defrost if it is a leak in the hub system if its in 4x4. If its a leak in the remaining part, it will be on defrost always.

 

A/C works fine,,,,,,, but I've never noticed what it does when I switch in into 4x4 on the dash.... I will check that out this evening ... If I understand ,,,,,, turn on a/c as normal , blowing thru vents then switch into 4x4 , I'm guessing low and the high to see if a/c acts up... Correct. If it does it the pump if it does not its a hose leak or leak in the hub .

 

Have the A/C on, if its blowing out the vents the pump is fine.

Switch to 4x4 hi range is fine, if the A/c starts blowing out the defroster, there is a leak between the Solenoid, and the lockout hub itself.