1. check to see which side of the axle holds a vacuum. This will tell you which side you need to fix.

2. You need to pull tire, brakes, hub asembly. axle shaft

3. the seal is inside the axle tube. replace it and reassemble.

It is a couple of hours labot.

 

For more info and step by step check out the links I posted earlier in the thread.

 

Keep in mind that anything from the solenoid to a broken vacuum line (after the solenoid) to a leaking hub/knuckle can cause the switch to defrost.

To test the solenoid, do this.

Trace the vacuum line that supplies vacuum TO the solenoid. Then, trace the vacuum line from the solenoid to a "T" that then goes to each knuckle.

Disconnect the line between the "T" and the solenoid, and plug the side going to the solenoid.

Turn the 4x4 switch and see if it still goes to defrost. If it does, the solenoid is leaking. Replace it.

Also, with a hand vacuum pump, supply vacuum to the "T" and see if it leaks down. If it does, you have a broken line or leaky hub/knuckle. Take off the hoses from the "T" and try each side to see which one leaks.

 

Can someone please put into into lamen's term. Thanks.

 

Mine started out switching to defrost when I engage 4wd and now it defrost all the time. I'm not sure where to start.

 

OK, I'll try to make this as easy to understand as possible.

This is a test to see if your front hubs on your Electronic Shift On the Fly (ESOF) 4 wheel drive system might have a vacuum leak. If you do not have ESOF, this does not apply.

1. Verify the front hubs are in the AUTO position.

2. Start the engine. Turn on the air conditioning. Select a medium speed so you can tell that the AC system is blowing out the vents.


NOTE: If you can't get the AC to blow out of the dash vents, but it starts with the AC blowing out the defroster vents, your vacuum leak is probably somewhere else, or (if you own a Power Stroke) your vacuum pump is not working.

3. Turn the ESOF selector to 4H.

4. Observe the AC vents. Did they stop blowing? Is the AC now coming out of the defroster vents (up on top of the dash)? If so one or both of your hubs have a vacuum leak somewhere. This could be caused by an internal hub seal or the vacuum line going from the vacuum solenoid to the hub, or could even be caused by the vacuum solenoid itself.

 

Thanks for that explanation.

I think my my hub are manual. It has LOCK/FREE on the turning cap.
I also have a manual floor 4x4 shift lever. So that means I don't have ESOF.

Question 1. (Educate me please)
Whats does the A/C (interior climate control) have anything to do with gearing fuction like 4x4 and front hub. Did ford get cheap and try to combine the two system or what? I would hope that two such different features would have two sepearate indendent systems. Again I do not understand the systems so please do educate. Sorry for my speculation.

Question 2. Manual Hub in 4x4
Since I have a manual hub. In the FREE position. Regardless of the floor shift position. I will alway be in 4x2 becuase power can never reach the front wheel. Power ends at the front drive shaft even if in 4x4. Is that correct?

 

ESOF hubs are locked by VACUUM.

The AC vents are controlled by VACUUM.

If the ESOF system has a vacuum leak, the AC vents will go to DEFROST because of the loss of VACUUM.

 

See krewat's answer above.

Correct. In this condition your front driveshaft, differential and axles will be spinning, but your wheels will not be connected to the axles, so you're still in 2 wheel drive.

 

Dear Mr. Redford and Mr. Krewat--

Thank you both for your respectful, entertaining and informative posts on this forum. As can be seen by my post count, I don't contribute much o' nothin', but I want you to know I try to read every post made by either of you fellows.

Based partly upon your opinions, I recently purchased a 2006 F250 CC XLT FX4 5.4 to haul my Four Wheel Camper and occasionally a utility trailer.

I had a problem with the ESOF hubs the first day of owning the vehicle and was able to convince the dealer of my diagnosis so that they repaired the vehicle gratis. This would not have been possible for me without the information gleaned from this forum.

Respectfully submitted,

Mark W. Ingalls

 

Mark, welcome to FTE

Glad we can help out, when I first bought my 2001 brand-new (in June of 2002) I used this forum a lot to get the lowdown on all the known issues, and what to look for.

It's turned out that I've been here now 6 years, and still learning, but still glad to help out whoever and whenever I can

Thanks!

 

sometimes you really need to take the time to get all the info before just listining to people with quick answers, I trouble shoot everything till i know exactly what it is.... by your vac test I knew it was one of the seals in the hub, but i had to make sure you were in fact testing the line to the knuckle and not the other way - byreading the posts from you and others i realized your test was valid so it was def one of the 2 seals in there. just some info... i have never in my life seen a vac sol go bad, I have heard of it though - from experience - mine had 60k miles on it and i removed it and it was still fine.

the seals in the hub are two fold.

there is a yellow o-ring that goes into the knuckle - this is about 4 bux from ford or there is the main knuckle seal at about 80 bux usa money from ford.

i replaced the seals myself when my seals were shot - auto hubs suck... here is a how to i made on how to do the conversion - i have an 03 - same as your 02

http://www.angelfire.com/fang/mercury/hub.pdf

hope this helps... i suggest getting in there and looking everything over...
cause if air cant stay in, it means water and debris can get in!


http://www.angelfire.com/fang/mercury/ball.pdf - this is a real teardown of the hubs...


i suggest going with warn manuals and then disconnecting the solenoid and plugging the lines up top, then use a 1/8" NPT nipple and thread it into the knuckle - i love my warn hubs

kenny