Understanding auto hub function
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Understanding auto hub function
I recently purchased a '04 Super Duty with the factory auto-lock hubs. I've already spent 45 minutes trying to sort through threads about this, and I'm trying to understand how the hubs function.
I was getting them to engage, but they wouldn't disengage, so I didn't suspect a vacuum problem. After reading more, I'm not sure I can discount vacuum.
So I disassembled hubs and cleaned and lubed per Guzzle's instructions, and they still don't unlock.
Now I understand that there is a vacuum pulse to engage and to disengage. My question is: Is it possible get the hubs out of sync with the vacuum pulses when remove and replacing hubs? The plastic detent piece with the pins can be in or out, and does it matter when replacing hubs?
Thanks!
I was getting them to engage, but they wouldn't disengage, so I didn't suspect a vacuum problem. After reading more, I'm not sure I can discount vacuum.
So I disassembled hubs and cleaned and lubed per Guzzle's instructions, and they still don't unlock.
Now I understand that there is a vacuum pulse to engage and to disengage. My question is: Is it possible get the hubs out of sync with the vacuum pulses when remove and replacing hubs? The plastic detent piece with the pins can be in or out, and does it matter when replacing hubs?
Thanks!
Lead Driver
Joined: Sep 2007
Posts: 8,180
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From: Scio, OR
The system uses a full vacuum pulse to lock and a half vacuum pulse to unlock. I don't have the exact numbers in my head but I can look them up if you need them.
You may have a bad solenoid or a leak. You need a vacuum gauge with a hand pump. The first test I would do is to connect the gauge to the output of the solenoid and have someone shift into 4WD and watch the vacuum pulse. Then shift out of 4WD and watch the pulse. It may take a minute or so when shifting out for the computer to go ahead and send the pulse to unlock the hubs.
You may have a bad solenoid or a leak. You need a vacuum gauge with a hand pump. The first test I would do is to connect the gauge to the output of the solenoid and have someone shift into 4WD and watch the vacuum pulse. Then shift out of 4WD and watch the pulse. It may take a minute or so when shifting out for the computer to go ahead and send the pulse to unlock the hubs.
9 ECHO 1
Joined: Aug 2009
Posts: 12,467
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From: Missouri
See if this helps.
I need to redo this video.
How To: Find and Diagnose ESOF Hub Vacuum Leaks - YouTube
I need to redo this video.
How To: Find and Diagnose ESOF Hub Vacuum Leaks - YouTube
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TNT in Round Rock
1999 - 2016 Super Duty
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Aug 15, 2007 04:10 PM
