Ford Powerstroke Diesel Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1 (Edited)
I have a 2002 with the NV273F. I have replaced the 4Wheel drive actuator solenoid, the vacuum pump has been replaced, The hubs don't hold a vacuum so I thought that was the issue but they still lock up in Auto. I checked this morning by grabbing my front drive shaft and it locks up so I took it out and tried backing up a hill to check but im not getting any spin from the front tires. I jumped out and grabbed the front drive shaft again and its locked up, no play so the transfer case is engaged? so I jumped back in again to try and still no spin from front tires. Anyone have any suggestions? I am out of options as far as my knowledge goes. Thanks
 

·
Registered
Joined
·
10 Posts
Discussion Starter #2
I been reading a few of the other posts. If the the hubs don't hold a vacuum and the transfercase is locked up in 4wheel, then the wheels won't lock up in manual? and for sure not in auto?
 

·
Registered
Joined
·
8,628 Posts
the superduty hubs are misleading. Auto is a kind of off and then vacuum acutated on system and lock is basically locking like old school hubs. Most likley the big yellow o ring inside the hub is failing or you have a vac leak in the engine bay. Look behind the passenger battery. There is a little vac pump, vac reservoir and a 4x4 solenoid. One line from the vac reservoir goes all the way down the frame to both hubs those crack all the time. In fact I capped mine and capped the hubs and now my auto is off and i have to get out but I usually turn them on if I even think i'll need them. Then turn them back to auto when i hit the highway etc.

also do you hear the vac pump run when you start the truck.engage the hubs? Also does your hot/cold air only blow through defrost or through all settings. Face, feet/floor, defrost?
 

·
Registered
Joined
·
10 Posts
Discussion Starter #4
Yes I hear the vac pump engage when I turn the switch. Funny you say, cause when I turn the AC on it either blows out the front vents or blows defrost, it's pretty random.
 

·
Premium Member
Joined
·
3,756 Posts
The vacuum pump should shut off in a few seconds unless you have a leak
A Doorman solenoid will cause a leak(manufacturing flaw) -- you need to get the Ford solenoid
A Harbor Freight hand vacuum with gauge will come in handy for checking leaks
Look for the line that goes toward the heater box and disconnect it, then plug the end to hold vacuum, this isolates the heater controls
With only the 4x4 system connected and the control in 2x4, the vacuum should hold and the pump shut off
Easiest to get the front up on stands to test the hubs
Turn the control to 4x4 and see if the front wheels lock to the axles -- vacuum pump should again turn off
if not there is a leak
you can isolate the vacuum lines at the wheel hubs by plugging one at a time to find which side is the problem
when this is all satisfactory -- move to testing the heater controls
all testing is done with the engine off
 

·
Registered
Joined
·
10 Posts
Discussion Starter #6
The vacuum pump should shut off in a few seconds unless you have a leak
A Doorman solenoid will cause a leak(manufacturing flaw) -- you need to get the Ford solenoid
A Harbor Freight hand vacuum with gauge will come in handy for checking leaks
Look for the line that goes toward the heater box and disconnect it, then plug the end to hold vacuum, this isolates the heater controls
With only the 4x4 system connected and the control in 2x4, the vacuum should hold and the pump shut off
Easiest to get the front up on stands to test the hubs
Turn the control to 4x4 and see if the front wheels lock to the axles -- vacuum pump should again turn off
if not there is a leak
you can isolate the vacuum lines at the wheel hubs by plugging one at a time to find which side is the problem
when this is all satisfactory -- move to testing the heater controls
all testing is done with the engine off
Thanks guys I'll get on that and let you all know what I find.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #7
So I put it in four wheel drive and jacked it up, both tires spin freely. What would I do next? Replace the hubs?
 

·
Premium Member
Joined
·
3,756 Posts
Did you even read my post?
 

·
Registered
Joined
·
10 Posts
Discussion Starter #9
Yeah I guess im getting a little ahead. I bought a vacuum pump and tested each hub and they don't hold a vacuum. I replaced the solenoid a couple weeks ago with an OEM. I didn't test the heater controls since both hubs won't hold a vacuum. Should I go ahead and test the heater controls next anyway?
 

·
Premium Member
Joined
·
3,756 Posts
Use the vacuum pump on the line heading to the heater, it should hold vacuum on the gauge
Possible one of the lines is cracked/worn and leaking vacuum
Also where the lines connect to the controls will sometimes work loose, just need to push the connector back in
 

·
Premium Member
Joined
·
3,756 Posts
Options on the hubs
Live without the auto function, you still have manual or repair them
the big seal on the axle is likely bad, that requires pulling the axles and using a special tool to replace the seals
would be a good idea to pull the hubs and check first tho, I have seen them get full of water and rust
 

·
Registered
Joined
·
10 Posts
Discussion Starter #12
I will check the heater lines next. Pull the hubs next paycheck I think. Manual doesn't work either.
 

·
Premium Member
Joined
·
2,645 Posts
Did you manually lock the hubs? The auto function commonly fails, and when you drivshaft wouldn't turn by hand that's because the transfer case was in 4x4 which locks the front and rear driveshafts together so they turn at the same speed, you won't be able to turn the front shaft in by hand in 4x4 even with the hubs unlocked.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #14
Yeah I manually locked the hubs with every test I did in Automatic and no go. I know I have major leaks in my hubs which I will have repair, then I think I will move on to the HVAC system. Thanks for all your help guys.
 

·
Premium Member
Joined
·
3,756 Posts
Get the front up on jack stands, then manually lock each hub and see if it turns the axle shaft for that side
sometimes the axle u-joints get bound up, so would be a good time to test for that
just angle the front wheels and lock the hubs, then rotate the wheel -- does it rotate smooth?
 
1 - 15 of 15 Posts
Top