Hubs need serviced?

4tonGT40

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I was wondering if the hubs on my 6.4 are serviceable or do they need replaced if they are acting up? Long story short my front drive shaft would spin while in 2H..I cycled the hubs from Auto to Lock and the drive shaft and axles spun free like it should. So I'm assuming that they are sticking somehow. Any ideas?
 

EvilTwins

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Im running into a similar situation, only opposite. Mine wont go into 4WD. The front shaft will engage when the switch is initiated , but the auto hubs wouldn't grab. I found that the right hub was a little difficult to engage manually and the difficulty engaging is probably the reason why the vacuum cant swing it. We will know for sure, just ordered a hub for the right side. For 120.00 i figured why rebuild it, just replace it and have a spare.

You issue might be the same core problem only working in the opposite direction. If one of your hubs is sticking in place the release wont happen. Just a thought.......

Did you pull it apart yet??
 

Erikclaw

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Usually, the hubs dry out and need some grease to lube them or a seal is leaking air so it won't engage.
 

4tonGT40

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Im running into a similar situation, only opposite. Mine wont go into 4WD. The front shaft will engage when the switch is initiated , but the auto hubs wouldn't grab. I found that the right hub was a little difficult to engage manually and the difficulty engaging is probably the reason why the vacuum cant swing it. We will know for sure, just ordered a hub for the right side. For 120.00 i figured why rebuild it, just replace it and have a spare.

You issue might be the same core problem only working in the opposite direction. If one of your hubs is sticking in place the release wont happen. Just a thought.......

Did you pull it apart yet??
No im going to pull them apart this weekend. You found new hubs for 120.00$? where? I called my local dealer and my cost on OEM hubs are 400.00 and some change! Thats why im rebuilding them. Plus I figured that its worth a shot, but for 120.00$ I would be all over that like stink on Chit....
 

EvilTwins

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No im going to pull them apart this weekend. You found new hubs for 120.00$? where? I called my local dealer and my cost on OEM hubs are 400.00 and some change! Thats why im rebuilding them. Plus I figured that its worth a shot, but for 120.00$ I would be all over that like stink on Chit....

They are very simple to pull apart, the three torx screws and pull em out. There is an "O" ring on the part you pull out and that is the main sealing portion. I can take a few pics if you want. Sorry I was a little off on the pricing. I just grabbed my estimate and for part number AC3Z*3B396*A the list price is $200.67 and my price was $154.11. I still think that buying one is worth it for piece of mind.


YEah it has a vacuum line that I could tap and put a grease fitting I guess, but I would rather just fix the one's I have. Have you done your this way?

I would be weary of that option since the pump that runs the 4WD system applies about 10 psi of vacuum and you wouldn't want the pumped in grease to get sucked into the lines. Especially when the hubs heat up and the viscosity changes. When I pulled mine apart I found that the grease was applied by hand directly to the hub assembly and never carried beyond the "O" ring.
 

Zmann

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like stated above
If you start pumping grease into the vacuum port your hubs probably won't get the vacuum siginal


u can lube the unit bearing through the ABS port the hubs are best lubed by pulling them off
 

Zmann

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It is easier to troubleshoot the system if you have a “Mityvac” vacuum pump. Turn the ignition switch to run (you don’t have to start the truck) and the air controls to vent and the fan control to low. If the truck’s vacuum pump comes on wait until it stops running before each test (open the hood and you’ll hear it better). First you need to remove both lines (left and right vacuum lines) from the hubs. Plug the passenger’s side line and attach the vacuum pump to the driver’s side line. Switch the dash controller to 4WD high. The vacuum gauge should go to 10 in.-Hg. or higher. (It should hold the vacuum at 10 in.-Hg. or higher for 45 seconds on engage and 15 seconds on disengage.) Repeat the test plugging the drivers side and testing the passengers side. If you have the right amount of steady vacuum the problem is probably in the hubs. If you do not have the right amount of vacuum or it is bleeding off, plug the lines back on the hubs and go to the next step. Second remove the vacuum lines from the PVH (Pulse Vacuum Hublock). This is the solenoid located on the passenger side fender well behind the battery and in front of the vacuum pump. Plug the vacuum tester into the lower hose and wait for the vacuum pump to build back up and shut off. The vacuum gauge should read and hold steady at 10 in.-Hg. or more. If it does, the vacuum reservoir should be fine and not leaking, so go on to the next step. Third, plug the bottom line back to the bottom of the solenoid and hook the vacuum gauge to the top barb of the solenoid (not the vacuum line but to the solenoid itself). Try switching between 2WD and 4WD again. The gauge should read 10 in.-Hg. for 45 seconds on engage and for 15 seconds on disengage. If it doesn’t it is probably the solenoid (PVH) on the fender that needs replacing. This was my problem so this was as far as I have gone. If all these things check out, THEN you need to go to the hubs and check them for leaks with the vacuum tester. Most of the time it’s a fuse, PVH, vacuum line or vacuum pump and not the hubs.
,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Unknown
 

EvilTwins

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It is easier to troubleshoot the system if you have a “Mityvac” vacuum pump. Turn the ignition switch to run (you don’t have to start the truck) and the air controls to vent and the fan control to low. If the truck’s vacuum pump comes on wait until it stops running before each test (open the hood and you’ll hear it better). First you need to remove both lines (left and right vacuum lines) from the hubs. Plug the passenger’s side line and attach the vacuum pump to the driver’s side line. Switch the dash controller to 4WD high. The vacuum gauge should go to 10 in.-Hg. or higher. (It should hold the vacuum at 10 in.-Hg. or higher for 45 seconds on engage and 15 seconds on disengage.) Repeat the test plugging the drivers side and testing the passengers side. If you have the right amount of steady vacuum the problem is probably in the hubs. If you do not have the right amount of vacuum or it is bleeding off, plug the lines back on the hubs and go to the next step. Second remove the vacuum lines from the PVH (Pulse Vacuum Hublock). This is the solenoid located on the passenger side fender well behind the battery and in front of the vacuum pump. Plug the vacuum tester into the lower hose and wait for the vacuum pump to build back up and shut off. The vacuum gauge should read and hold steady at 10 in.-Hg. or more. If it does, the vacuum reservoir should be fine and not leaking, so go on to the next step. Third, plug the bottom line back to the bottom of the solenoid and hook the vacuum gauge to the top barb of the solenoid (not the vacuum line but to the solenoid itself). Try switching between 2WD and 4WD again. The gauge should read 10 in.-Hg. for 45 seconds on engage and for 15 seconds on disengage. If it doesn’t it is probably the solenoid (PVH) on the fender that needs replacing. This was my problem so this was as far as I have gone. If all these things check out, THEN you need to go to the hubs and check them for leaks with the vacuum tester. Most of the time it’s a fuse, PVH, vacuum line or vacuum pump and not the hubs.

This appears to be the proper troubleshooting process as described in the Ford manual with the exception of the Solenoid being located on the passenger side of the fan shroud on our trucks. This appears to be for a 6.0. If your vacuum system is a concern you could just do what I did and remove all the wacky plastic lines, fittings, transition tubes, rubber 90s, and the kitchen sink and just install new rubber lines from the solenoid to the hubs. Its about 14 ft of line and one "T" fitting. This leaves only the hubs and pump itself as a possible issue.
 

EvilTwins

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If it retained the electronic push button 4WD I would be all over them. I read the site and it appears that you are back to the old get out and twist method.


Resentment is like drinking poison and waiting for the other person to die.
 

Dzchey21

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If it retained the electronic push button 4WD I would be all over them. I read the site and it appears that you are back to the old get out and twist method.


Resentment is like drinking poison and waiting for the other person to die.

I follow this practice anyway with stock hubs and it sure helps them live.

I.actually drive around with my hubs locked in almost all the time... don't notice.that big of a mileage drop...
 

Jhaddox

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I follow this practice anyway with stock hubs and it sure helps them live.

I.actually drive around with my hubs locked in almost all the time... don't notice.that big of a mileage drop...

x2


Sent from my iPhone using Tapatalk
 

EvilTwins

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I follow this practice anyway with stock hubs and it sure helps them live.

I.actually drive around with my hubs locked in almost all the time... don't notice.that big of a mileage drop...

Definitely something to think about in regards to leaving them locked. It drives me insane that something doesn't work properly. YEA!!! O.C.D

I guess it would come down to the additional rotating mass. You don't notice a difference in turning?


Resentment is like drinking poison and waiting for the other person to die.
 

Dzchey21

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Definitely something to think about in regards to leaving them locked. It drives me insane that something doesn't work properly. YEA!!! O.C.D

I guess it would come down to the additional rotating mass. You don't notice a difference in turning?


Resentment is like drinking poison and waiting for the other person to die.

Ill be honest I.never notice my hubs being locked it. And mileage seams almost the same. If I hit the highway for a long trip ill unlock them but that's about it.
 

4tonGT40

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They are very simple to pull apart, the three torx screws and pull em out. There is an "O" ring on the part you pull out and that is the main sealing portion. I can take a few pics if you want. Sorry I was a little off on the pricing. I just grabbed my estimate and for part number AC3Z*3B396*A the list price is $200.67 and my price was $154.11. I still think that buying one is worth it for piece of mind.




I would be weary of that option since the pump that runs the 4WD system applies about 10 psi of vacuum and you wouldn't want the pumped in grease to get sucked into the lines. Especially when the hubs heat up and the viscosity changes. When I pulled mine apart I found that the grease was applied by hand directly to the hub assembly and never carried beyond the "O" ring.
I probably should give my dealer a Vin # BC the price he quoted me is over 400$ my cost per side...Thats a Hell NO, but 200 per side maybe..Im not going to do away with the auto hubs, I will take mine apart rebuild them and Im sure it will all be good. All my vacuum lines are good and they engage but dont seem to want to disengage or vise-versa. Really there isnt much that can go wrong inside them so I think rebuilding them is a good start. Send me a pic of the one you bought please. Thanks for the input
 

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