Anyone have any tips/pointers/suggestions for doing this? Is it even possible? I know AE can do a lot, but I haven't had a chance to figure out much of it yet.

 

Depends on the ESOF issue. If it's something to do with the transfer case (and 4x4 light) maybe, but I doubt it will be able to do much about the hubs (unless it can somehow monitor the vacuum pulse for the lock/unlock).

 

I've got the famous "no 4x4, heater defaults to defrost" issue.

 

As long as your 4x4 light comes on the dash (and you hear/feel the t-case engage), you are looking at a vacuum leak. I had the same issue when I first bought the truck and found a vacuum leak, a bad solenoid and a frozen hub (the $$$ trifecta ). There's a lot of good info on here about that.

Here's something to point you towards a solution:

https://www.ford-trucks.com/forums/7...with-esof.html

 

I know I'm looking at a vac leak, just wondering if AE can help chase the problem down. I'm going to buy a Mityvac and see if I can find the dang leak.

 

The hub locking portion is all mechanical (except the solenoid operating). I don't remember seeing any sensors or taps in the line when I was tracing out the system to find my problems.

I used a vacuum pump to find my leaks too. There is a rubber line coming off of the solenoid (over the passenger's side wheel well under the hood) that has a connector that goes to a plastic line. The plastic line is what runs under the engine and to each wheel well. From there it connects to a rubber hose that goes to the steering knuckle.

Some places that are prone to wear and damage with age are the connection at the steering knuckle and some of the seals inside the knuckle/hub cavity. Inside there you have an axle seal (on the inside of the knuckle), a hub-to-knuckle seal (a yellow o-ring that is in a groove on the hub assembly) and a locking hub seal (a black o-ring that is in a groove on the locking hub assembly). The locking hub assembly is the smaller black piece in the center of the wheel that has the auto/lock selector on it the manually lock the hubs.

If you don't use 4x4 very much (it is recommended that you engage it at least once a month to keep everything working), you might want to look into cleaning the locking hub assemblies. Here's a good link for that:

Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page

The locking hubs are pretty easy to remove and a little preventative maintenance will make the $350 hub last longer.

 

The most prone area of vacuum leaks is the rubber line going to the hubs in the wheel well. They get exposed to all types of abuse and can crack over time.

 

I replaced both the rubber hoses going from the frame to the knuckles about 2 years ago when I did ball joints on the driver's side. Its possible one of them has failed already, but I really think its probably the big seal in the knuckle. It has been in bad shape for a while now. My ESOF problems are intermittent so that tells me its a seal somewhere, I think

 

Chase,

Just isolate which hub has the leak by pulling and plugging the vac line at each hub. When the HVAC doesn't default to defrost you found the leak.

Unless both hubs are leaking you only have to pull and plug one vac line. If it doesn't default to defrost that is the hub that leaks. If it does default then it is the other hub. If you what to confirm then just do the same thing on the other side.

 

I will try that. Then once I find where the leak is I think some 100 mph tape ought to solve the problem

 

Could be that yellow o-ring behind the hub and knuckle. Good luck.

 

If the leak is in the hub assembly somewhere, you won't know where it is until you tear it apart (and then you may not be able to see any apparent damage). It's not too difficult, but it does take time and depending on if you find the leak or just throw parts at it (like I did), the $$$ adds up quick.

 

I would use the Z rated tape.