auto 4x4 stopped workn
 

ive read the TSBs but havent done any work yet, i either have a pump leak problem or a hub problem, also, before it went out, when i switched from auto 4x4 into 2x4 my heater would switch to defrost like there was a leak, but now it does nothing, but, if i engage the hubs manualy, and then switch
the knob to 4x4 it works fine.

any ideas where to start, thanks.

If the heat or ac is switching to the defrost vents when you select 4X4 there is a vacuum leak. The nipples at the hubs are common spots.

define position of nipple. is that where vac. line enters top of nuckle,
also, how to test.

That is it. Remove the line and plug it (both Wheels) then engage 4X4. if the AC/Heat does not switch to the defrost the leak is in the hub (reattach 1 at a time to pin point). If the AC/Heat still changes to defrost vents trace lines back toward the pump to find the leak.

thanks, will try it out

Bigtorque,I had that problem when I tried to put my truck into 4x4. Didn't have the heater problem though. I had to lock the wheels manually also. Well It was as Amiller said. At the knuckle on both wheels. The Vacuum lines were so deteriorated that they weren't even attached to the knuckle any more,just hanging. I replaced both with new vaccum lines and zipped tied at both ends. Worked great!!!

I'm having the same problem. Do you have to take off the tire to remove the vacuum line? Also how to you remove them from the knuckle?

No you don't need to pull of the tires. Turn your wheel in one direction so that you can access the back of the wheel thats pointing outward. Then just find the black hose on top of the knuckle and pull it off. It will probably fall apart in your hands and also leave a black residue on your hands as mine did. Yeah these hose rot out and fall apart leaving you with a vacuum leak. I wish i had pics for yah but I don't Sorry,.

How hard is it to replace those lines?

I'm sorry Chance I forgot to mention, they're very easy to replace and they're just pushed on. There is nothing holding them on. I zipped tied mine just for my peace of mind. You can remove one and take with you to size it at your parts store and then replace it when you get home. I checked the ports for any obstrcutions before replacing the with new hose. But mine were off the ports also so just to make sure, I checked them because an obstruction will also not let the hubs ingage. Hope this helps yah out.

Chance I took some pictures of the line you need to check and replace if damaged. I can send them to you thru my e-mail. My e-mail is countrycar@hotmail.com..If you need them let me know and I will send them to you. Take care.

Guys, I have the same problem with the ESOF not engaging the hubs. When I turn on the 4WD, the AC goes off and the defrost goes on. I looked for a vacum leak in the hubs but have not found anything. One thing I did notice is that when I accelerate, I hear what sounds like a vacum leak under the dash. Sounds like it is coming from behind the radio. The more acceleration, the more pronounced the sound is. Just curious that since vacum to the hubs and something in the AC is connected, could there be a leak I should be looking for somewhere in the dash that may also fix the hubs???

Their is a vaccum pump that the lines connect to on the passenger side under the hood.

If you hear noise from behind your radio, its probably the turbo up pipes leaking. There's an active thread right now on that issue. Check it out here:
https://www.ford-trucks.com/forums/6...pipe-leak.html

I would check the hvac vacuum lines where they connect right behind the glovebox just to be sure.

as far as other vacuum leak points, I had my line right behind the pass side battery rot out from what was probably my carelessness when cleaning corrosion off the battery terminals. If you are good at the hub connections, I would start at the vacuum pump on the pass side and check all the tees and go from there.

good luck,

Austin

not trying to steal the thread but can anyone tell me what lines go to the T's on the air pump? I have 2 T's but one end is missing a hose. I can't find it anywhere and don't know what it goes to.