ESOF question
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Hotshot
Joined: Jan 2010
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From: Bristol, TN.
ESOF question
I have my vacuum system back up and working and using my vacuum pump I determined my lines are all good. They hold a vacuum fine, but my ESOF isn't engaging my hubs. I guess that leaves either the selector on the dash or the seal at the hubs.
If it is the selector, I should just be able to just disconnect the vacuum line at the selector and use my pump to engage my hubs. Anyone know how much it is supposed to take to activate the hubs?
Steve
If it is the selector, I should just be able to just disconnect the vacuum line at the selector and use my pump to engage my hubs. Anyone know how much it is supposed to take to activate the hubs?
Steve
Cargo Master
Joined: Nov 2005
Posts: 2,768
Likes: 58
From: East Tawas, MI
Steve.
If you have a good hold on vac. Chances are your hubs are shot. Does the 4x work when you manually select at the hubs? If it does, therein lies the problem.
I went thru this for 12 years and finally decided the bother-hood of FTE was right and went with Mile-marker premium hubs. If you need to shift on the fly, leave them locked in. Otherwise, I run open until an event and I've scrubbed that problem off my sheit list.
Denny
If you have a good hold on vac. Chances are your hubs are shot. Does the 4x work when you manually select at the hubs? If it does, therein lies the problem.
I went thru this for 12 years and finally decided the bother-hood of FTE was right and went with Mile-marker premium hubs. If you need to shift on the fly, leave them locked in. Otherwise, I run open until an event and I've scrubbed that problem off my sheit list.
Denny
More Turbo
Joined: May 2016
Posts: 717
Likes: 9
I have my vacuum system back up and working and using my vacuum pump I determined my lines are all good. They hold a vacuum fine, but my ESOF isn't engaging my hubs. I guess that leaves either the selector on the dash or the seal at the hubs.
If it is the selector, I should just be able to just disconnect the vacuum line at the selector and use my pump to engage my hubs. Anyone know how much it is supposed to take to activate the hubs?
Steve
If it is the selector, I should just be able to just disconnect the vacuum line at the selector and use my pump to engage my hubs. Anyone know how much it is supposed to take to activate the hubs?
Steve
1. Disconnect the Connector and see if there is 12 vdc when the switch is activated. If no, the problem is the (+), fuse/wire/Switch. Easily diagnosed with a Test Lamp or DVOM. If this test passes,
2. Place your vacuum Gauge / Pump on the output side and see if there is vacuum pulse when the switch is engaged. No, replace the PVM. If passes,
3. Do the same at each Vacuum Line at the Hub. No, bad vacuum line. Passes,
4. Pull your Hubs and clean, grease, new seal and reinstall using Guzzles Procedure (Google Search). The only other Gasket is the Yellow Hub Gasket which requires removing the Wheel Hub to replace.
Just curious, do the engage manually?
Thread Starter
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Hotshot
Joined: Jan 2010
Posts: 10,060
Likes: 491
From: Bristol, TN.
Steve.
If you have a good hold on vac. Chances are your hubs are shot. Does the 4x work when you manually select at the hubs? If it does, therein lies the problem.
I went thru this for 12 years and finally decided the bother-hood of FTE was right and went with Mile-marker premium hubs. If you need to shift on the fly, leave them locked in. Otherwise, I run open until an event and I've scrubbed that problem off my sheit list.
Denny
If you have a good hold on vac. Chances are your hubs are shot. Does the 4x work when you manually select at the hubs? If it does, therein lies the problem.
I went thru this for 12 years and finally decided the bother-hood of FTE was right and went with Mile-marker premium hubs. If you need to shift on the fly, leave them locked in. Otherwise, I run open until an event and I've scrubbed that problem off my sheit list.
Denny
Thread Starter
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Hotshot
Joined: Jan 2010
Posts: 10,060
Likes: 491
From: Bristol, TN.
The PVM (Pulse Vacuum Module) momentarily pulses 15 Hg which activates the Hub Locks.
1. Disconnect the Connector and see if there is 12 vdc when the switch is activated. If no, the problem is the (+), fuse/wire/Switch. Easily diagnosed with a Test Lamp or DVOM. If this test passes,
Since I have a dash light when selected does that not indicate the switch is working?
2. Place your vacuum Gauge / Pump on the output side and see if there is vacuum pulse when the switch is engaged. No, replace the PVM. Is PVM pump vaccuum motor? If passes,
3. Do the same at each Vacuum Line at the Hub. No, bad vacuum line. Passes,
Lines at both hubs hold a vacuum
4. Pull your Hubs and clean, grease, new seal and reinstall using Guzzles Procedure (Google Search). The only other Gasket is the Yellow Hub Gasket which requires removing the Wheel Hub to replace.
Just curious, do the engage manually?
1. Disconnect the Connector and see if there is 12 vdc when the switch is activated. If no, the problem is the (+), fuse/wire/Switch. Easily diagnosed with a Test Lamp or DVOM. If this test passes,
Since I have a dash light when selected does that not indicate the switch is working?
2. Place your vacuum Gauge / Pump on the output side and see if there is vacuum pulse when the switch is engaged. No, replace the PVM. Is PVM pump vaccuum motor? If passes,
3. Do the same at each Vacuum Line at the Hub. No, bad vacuum line. Passes,
Lines at both hubs hold a vacuum
4. Pull your Hubs and clean, grease, new seal and reinstall using Guzzles Procedure (Google Search). The only other Gasket is the Yellow Hub Gasket which requires removing the Wheel Hub to replace.
Just curious, do the engage manually?
It seems to me, the test for that would be to activate the hubs using my vacuum pump. If I can, I am upstream from the solenoid to the selector switch.
Steve
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
The rubber diaphragm inside the hub, that's actuated by the vacuum pulses, works on a little piece that works a lot like a ball-point pen mechanism.
Click-on, click-off.
There's a plastic component that is caught by a couple of tiny wires each shaped in an "L". The wires eventually wear out the plastic and the whole thing no longer operates.
It's pretty futile to attempt to make it work again once it stops.
When all that happens, the usual failure mode is "won't dis-engage". That means your front axles are always turning, even if the transfer case isn't driving them.
That creates a drive-line drag that will kill about one MPG of fuel economy, and contributes to excess wear.
Pop
Click-on, click-off.
There's a plastic component that is caught by a couple of tiny wires each shaped in an "L". The wires eventually wear out the plastic and the whole thing no longer operates.
It's pretty futile to attempt to make it work again once it stops.
When all that happens, the usual failure mode is "won't dis-engage". That means your front axles are always turning, even if the transfer case isn't driving them.
That creates a drive-line drag that will kill about one MPG of fuel economy, and contributes to excess wear.
Pop
Thread Starter
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Hotshot
Joined: Jan 2010
Posts: 10,060
Likes: 491
From: Bristol, TN.
The rubber diaphragm inside the hub that's actuated by the vacuum pulses works on a little piece that works a lot like a ball-point pen mechanism.
There's a plastic component that is caught by a couple of tiny wires each shaped in an "L". The wires eventually wear out the plastic and the whole thing no longer operates.
It's pretty futile to attempt to make it work again once it stops.
When all that happens, the usual failure mode is "won't dis-engage". That means your front axles are always turning, even if the transfer case isn't driving them.
That creates a drive-line drag that will kill about one MPG of fuel economy.
Pop
There's a plastic component that is caught by a couple of tiny wires each shaped in an "L". The wires eventually wear out the plastic and the whole thing no longer operates.
It's pretty futile to attempt to make it work again once it stops.
When all that happens, the usual failure mode is "won't dis-engage". That means your front axles are always turning, even if the transfer case isn't driving them.
That creates a drive-line drag that will kill about one MPG of fuel economy.
Pop
Steve
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Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Also remember that the depth of the vacuum pulses is different from click-on than from click-off. It's pulling that little click mechanism different amounts.
I don't remember which utilizes "more" (deeper) vacuum, but if it's click-off that's deeper, and you're drawing more vacuum than that, it may just stay off.
Pop
I don't remember which utilizes "more" (deeper) vacuum, but if it's click-off that's deeper, and you're drawing more vacuum than that, it may just stay off.
Pop
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Thread Starter
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Hotshot
Joined: Jan 2010
Posts: 10,060
Likes: 491
From: Bristol, TN.
Also remember that the depth of the vacuum pulses is different from click-on than from click-off. It's pulling that little click mechanism different amounts.
I don't remember which utilizes "more" (deeper) vacuum, but if it's click-off that's deeper, and you're drawing more vacuum than that, it may just stay off.
Pop
I don't remember which utilizes "more" (deeper) vacuum, but if it's click-off that's deeper, and you're drawing more vacuum than that, it may just stay off.
Pop
Any idea where I can track that pulse info down (I'll search the Internet unless there is an obvious) and if it is stuck off, if I work it manually should that not release it?
Cargo Master
Joined: Nov 2005
Posts: 2,768
Likes: 58
From: East Tawas, MI
Correct!!! You can sweep your whole house and still hold vac even if the hubs are shot.
Depending on where you live (mountains) and need the f-off. (that's what I call the system) you can try to repair your stock hubs. I've bought many new and (a few used (when available) . I've also shipped out to fellow FTE bro's everything in stock for free including the shipping :'). If you use 4x4 rarely and your not big on working on the system regularly, my addy is go maual hubs and turn them when u think u need them.
Warn, Milemarkers, whatever. Just get the bulletproof one. Sorry I can't pinpoint your solution. Many tried on my failures, and many lost. Just cheaper and easier and when u need it, it's engaged.
Denny
Depending on where you live (mountains) and need the f-off. (that's what I call the system) you can try to repair your stock hubs. I've bought many new and (a few used (when available) . I've also shipped out to fellow FTE bro's everything in stock for free including the shipping :'). If you use 4x4 rarely and your not big on working on the system regularly, my addy is go maual hubs and turn them when u think u need them.
Warn, Milemarkers, whatever. Just get the bulletproof one. Sorry I can't pinpoint your solution. Many tried on my failures, and many lost. Just cheaper and easier and when u need it, it's engaged.
Denny
Thread Starter
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Hotshot
Joined: Jan 2010
Posts: 10,060
Likes: 491
From: Bristol, TN.
Hey, I appreciate all the feedback. I love diagnostics, but I don't want to fall down the rat hole of no return. They work fine manually now and I only need them to back our fifth wheel up into the lot next to the house.
I'll likely chase it a bit further, but understand I have been warned.
I'll likely chase it a bit further, but understand I have been warned.
Cargo Master
Joined: Nov 2005
Posts: 2,768
Likes: 58
From: East Tawas, MI
A few years, but with the vac gauge...........should be an initial loss of less than next to nothing (can't recall) when the esof is triggered. And then an immediate stabile reading of prior. Never a plus or minus when the system was good.
:')
:')
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Take a look at the second half of Post #8 in this thread:
https://www.ford-trucks.com/forums/1...b-problem.html
Though it's a four-year-old post, Greg's still around, and you could PM him if necessary.
Pop
https://www.ford-trucks.com/forums/1...b-problem.html
Though it's a four-year-old post, Greg's still around, and you could PM him if necessary.
Pop