Red Monkey
Full Access Member
I tried mine yesterday and man do they engage! If the truck isn't running you will KNOW it when you hit the 4x4 switch, it sounds kinda neat!! That may be a good way to test your hubs to see if they are engaging.
ESOF question
- Thread starter fullthrottle99
- Start date
Does anyone know what pressure should be comming off the 12v vaccuum pump? Mine won't stop running, if I assist it in pulling a vaccuum on the resevoir it'll hold and shut off. But other than that it runs continously without providing enough for the hubs/vent selections
2001 7.3 F-250 4 door 4wd
2001 7.3 F-250 4 door 4wd
Last edited:
jestersv
7.3 addict
you don't read pressure with vacuum its inches of vacuum
Bolt
Full Access Member
It's inches of mercury. Inches for short. It sounds like you have a vacuum leak, not real fun to trace everything down, but not impossible. Check the hoses starting at the hubs and work back, or on the HVAC unit.
no-red 6 0
Senioritis
iirc: ask me how i know..... that dealer says something like 15 to engage and 7 to disengage... some crazy numbers like that...
to find out for sure, just call the dealership and ask... i just looked, you have the 7.3 - not sure if they are the same.
to find out for sure, just call the dealership and ask... i just looked, you have the 7.3 - not sure if they are the same.
i havent had to trouble shoot mine <YET> but cant you
just pull the lines off the pump one at a time, sealing the
pump side connection and see if the pump turns
off...repeat (one line off at a time) til you discover
which line may have the leak
just pull the lines off the pump one at a time, sealing the
pump side connection and see if the pump turns
off...repeat (one line off at a time) til you discover
which line may have the leak
Sorry I ment the inverse of presure, anyway, hubs are good, I can hook vacuum pump directly to the output of the 4wd seleniod and it holds at 16 on the vacuum gauge. I can hook the pump up normally, blocking off where it comes out of the vacuum resevior goin to the 4wd selenoid, just utilizing where it goes into to cab for the heater controls and it holds at 16. Seems at this point my 4wd hub lock/vacuum switch has sprung a leak. I didn't even know it has self locking hubs, I'm guessing it's controled from the 4wd switch in the dash. All this newfangled stuff sure isn't like my old '78 Bronco or '76 Chevy. Thanks for the help guys.
Last edited:
Vacuum lines and or the vacuum pump are the most common reasons for the ESOF hubs not engaging.
Other reasons can include worn inner and outer orings as seen below. You should also pull the 4x4 hub(first pic) and lube it every once in a while.
Tbar
Other reasons can include worn inner and outer orings as seen below. You should also pull the 4x4 hub(first pic) and lube it every once in a while.
Tbar