4x4 wont engage??!!

[stevenc1]

Front hubs/4x4 Dont work while in "auto" ??

--------------------------------------------------------------------------------

Hi there,
Big snow up here in KS over the last few days...big.

Switched the "dial on the dash" to 4HI and the light came on BUT no front drive.

Pulled the hub covers off the moto metal wheels and the selector switch was in "auto"...so, I switched it to "lock" and it worked.


When I swith the "dial on the dash" back to 2wd, it does indead deselect the front wheels and works fine when I switch it back to 4hi.

However, why is my "auto" not working on the hub?
Is it okay to leave it in "lock"?

[RHFDpowerstroke53]

not a surprise. Common problem with SuperDutys. Its ok but you are turning the whole front driveshaft. More work and your MPGs are gonna fall. They are vacuum controlled and there is probably a leak in your lines. Make sure its not your vacuum pump. You'll know its the pump because the A/C will only come out of the defrosted. Mine does the same thing. I just get out and lock em when i need 4x4

[07R1]

I ran into the same problem last week during the snow/ice storm in DFW. I traced the problem to the vacuum lines running to the hub. I will replace the lines and hopefully it is fixed. Turn your a/c or heater to high and click over to 4-hi. If the defroster starts blowing you have a vacuum leak.

[Chiller]

I had a similar issue and it just showed it self in the last cold week we had here in NJ. I was not able to get my auto hubs to lock in either. Now im not saying vaccum pressure does not play a role in the malfunction. However, I have noticed that with auto locking hubs you want to lock try switching from 2wd to 4wd-hi at speed. It worked for me, when I was standing still they did not lock, however at speed (20mph) They locked in fine...try it. I would still check over your system though to pin point the problem.

[asian195]

definitely sounds like a vacuum leak. there are also 2 o-rings on the hubs themselves that can fail. i should say, 1 on the locking hub itself and 1 on the unit bearing. if you have a defrost problem try pulling the vacuum line off the hubs plug them and try the heater again. if no more problem, unplug one line hook it back up and repeat heater check, then switch the vacuum lines, the other side hooked up and one plugged and repeat check. youll then know which one or both hub 0 rings are leaking. if problem persists while both lines plugged, leak is somewhere else..

[stevenc1]

Okay, so...found out it was INDEED a vacuum leak. Had a small hole in the ol' hose. Fixed that. Then, also replaced the vacuum solenoid.

Also...on TOP of all of this...I am experiencing what I believe to be another issue!!

The "ol something is wrong with my heating and A/C dealio" problem!

Now, after the fixes...my 4x4 works fine...all is good there.

However...HOWEVER!

I do not have any air coming out of my vents...only the defrost and the lower heater vents.

What gives?
What next!?

(Mods...please move parts of this to another forum if needed)

Thanks!

[dhanna6powerstroke]

Originally Posted by stevenc1

Okay, so...found out it was INDEED a vacuum leak. Had a small hole in the ol' hose. Fixed that. Then, also replaced the vacuum solenoid.

Also...on TOP of all of this...I am experiencing what I believe to be another issue!!

The "ol something is wrong with my heating and A/C dealio" problem!

Now, after the fixes...my 4x4 works fine...all is good there.

However...HOWEVER!

I do not have any air coming out of my vents...only the defrost and the lower heater vents.

What gives?
What next!?

(Mods...please move parts of this to another forum if needed)

Thanks!

You still have a vacuum leak. Check and see if the small grey hose is off the black heater valve that is inline with the heater hose.