When servicing the hubs i realized I could not turn them manually by hand anymore, from lack of use apparently. Since I cant turn them by hand anymore, assuming the rest of the system is functional, will they lock in automatically or no? Does anybody have any ideas on how to free the selector up/
They can still lock with vacuum. Drill a hole in the dial and inject silicone lube into it, you can easily remove the hub to do this. Work the dial with pliers.
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Brent Bradley Scenic photographer and former mechanic with car and motorcycle drag racing background. Also, avid snowmobiler.......retired. The Ex; custom mudflaps
are you thinking right in the center of the dial? or off to the sides? Thanks for the info on them still working, I must have another issue still.
Off to the sides. You can put a sheet metal screw in the hole afterwards also.
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Brent Bradley Scenic photographer and former mechanic with car and motorcycle drag racing background. Also, avid snowmobiler.......retired. The Ex; custom mudflaps
I threw a vacuum gauge on the system tonight. The drivers side at the end of the hose that goes into the barb has pressure. 20 hg as i recall which seems sufficient, the passenger side appears to have very little as the needle hardly moved. Anybody have any ideas? I didnt think there was a leak because the hvac is running properly, but there very well may be. Also, it makes sense in my mind that even with vacuum going to one hub, the truck should bind when steering on dry surfaces, its smooth as ever. I tested coming right off the pvh solenoid, the red air hose has pressure, the black one doesnt. Can anybody shed some light on where to go next, or better yet where I could get a schematic of hose routing. Thanks everyone again!!
You need to understand the logic of the ESOF operation before you keep shooting blanks at this. The hubs use a pulsed vacuum system that does not apply a constant vacuum to the hubs. The hubs are sent a high vacuum signal to engage then the vacuum is stopped. The hubs are now locked and will stay that way until they are sent the vacuum signal to unlock, which is a lower vacuum signal than the lock signal. The hubs will stay unlocked until they receive the lock signal again.
Switching the 4x4 switch back and forth while you are testing will eventually lead to the module leaving the hubs locked for an extended period of time. The module does this to prevent unnecessary locking and unlocking of the hubs if you are driving in intermittently slippery conditions. This is why it is a bad idea to use the 4x4 switch to test the vacuum system for a long period of time. You will eventually think there is a problem when the system doesn't unlock the hubs, but in reality this is the way it is designed to work.
Testing the vacuum portion of the hubs is easy and takes literally a few minutes. To do this, you need a vacuum pump, not just a gauge. If you don't have one you can pick one up at the parts store for twenty bucks. You are looking for something similar to a "Mity-Vac" hand vacuum pump. Google it if you don't know what it is.
Pop the hood and go to the passenger side. Coming off the ESOF vacuum solenoid is a vacuum line that runs down the fender to the axle and eventually the knuckles and hubs. There is a rubber connector for the vacuum line not far from the ESOF solenoid. Disconnect it and hook the vacuum pump to the part that runs down the fender. Pump up the pump about 20 times or so. If you get a vacuum reading and it stays up and doesn't bleed down, the problem isn't from that point down to the hubs, the problem is with the ESOF solenoid, vacuum supply, or is an electrical control problem. If you can't get a reading on the vacuum gauge, there is a leak in the system. Disconnect the vacuum line at one of the knuckles and hook the vacuum pump to it and pump it up. If you get a good reading and it doesn't bleed down, the hub and seals are good. If both knuckles hold vacuum, then the problem is in the lines from the solenoid to the hubs. If one or neither of the hubs hold vacuum, then the hub needs to be torn apart and the seals and o-rings replaced.
Honestly, that is all there is to it. It really takes longer to type this out than it does to do the test. I do this several times a week as a tech at a dealership during the wintertime.
Thank you! That was one of the BEST explanations of how the vacuum part of the ESOF system works!
I went to rep you and found I "need to spread it around", so I must have recently repped you already for something else I thought noteworthy.
Thank you for sharing your obviously skilled knowledge with us.
Pop
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I did not know that the hubs would stay locked if you kept cycling the switch. Good to know!
IIRC it takes around 10" vacuum to lock and about 6" vacuum to unlock. The pulse only lasts for around 30 seconds and only needs to be applied for around 15sec to engage/disengage the locking hub.
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I found out the hard way about the ESOF strategy when they first came out, then finally went to the manuals and got educated. Ford has put out several special service messages and I think maybe a TSB about the way the sytem works, so I'm sure there were many techs replacing parts that were working fine. This system was quite a bit different than anything Ford had used in the past and it's funny, looking back, at the time I thought this was a ridiculously complicated system until I got to work on a few and figure them out.
Also, as another bit of mystery info, the ESOF solenoid sends the "unlock" vacuum signal to the hubs each time the truck is started. This is to reset the hubs in case one or both didn't properly unlock during the last time the 4x4 was switched back to 2wd. This is why on some trucks with leaking hub seals the HVAC sytem will momentarily default to the "defrost" position after startup, due to the loss of vacuum in the system through the hub seal or o-ring. This only lasts as long as the "unlock" signal is sent by the solenoid. Once the solenoid turns off, vacuum builds in the system and the HVAC control doors go back to their intended positions. If this happens on your truck, it is a symptom that your hub seals are probably going out.
Very good Jay and it's good to know that Ford made a good decision by inducing some vacuum when it starts becuase mt hubs don't always want to come out of lock right away. In fact I was just thinking last night Ford would be smart if they did that.
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Brent Bradley Scenic photographer and former mechanic with car and motorcycle drag racing background. Also, avid snowmobiler.......retired. The Ex; custom mudflaps
Im pulling almost 20 mm hg in vacuum to lock and unlock both sides. I cant find any leaks in the system, hvac system still doesnt default to defrost which should reinforce the no vacuum leak idea. Time for new hubs? Does anybody have any specs on vacuum regarding lock and unlock?
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