Could someone explain where the vacuum enters the locking hub? Is it through the hole in the splined axle? I'm having the same problem with my 02 f-350.

FYI guys and gals. When changing the oil be sure to change the oil in the top of the engine to keep your injectors from going bad.. You will not believe how dirty it is. I just found out about this after owning my truck for seven years.

 

The vacuum line attaches to the top front of the knuckle and goes into the hub cavity. After that, here's the best that I can tell:

There is a plastic "washer" that has 4 grooves in it that directs the airflow. The air is sucked out of the hub cavity and the differential pressure will cause a diaphragm to actuate in the locking hub, which in turn locks the hub and now the wheel will turn with the axle. The same is done to reverse it, but the diaphragm action will unlock the locking hub. The key is to have a good seal throughout the system to be able to generate the vacuum pulse to cause this to happen. Things that can go wrong: vacuum solenoid (located above the right front wheel well near the quarter panel wall), vacuum line leaks to the knuckle, the actual connection at the knuckle, leaking seals (that includes the inner axle seal, hub-to-knuckle seal which is a yellow o-ring, and the locking hub seal which is a black o-ring) and frozen/sticking locking hubs.

I assume you are referring to a diesel engine. If you are referring to the HPOP reservoir at the "top of the engine", it is a point of contention. That oil is constantly cycled through from the pan, to the reservoir, through the injectors and back to the pan. It's only about .75 qts in that reservoir which is only about 5% of the oil capacity. You already have oil coating everything in the engine anyway so you can never truly change out all the fluid, it will be contaminated by old oil regardless. Many feel it is not worth the trouble to change it out. I have only done it once and yes, it was black. It does not take much to round out the inside of the reservoir plug or possibly damage it by over-torquing it. Not to mention that you need some kind of suction rig with a line small enough to snake in their anyway. Also, you run the possibility of damaging the screen inside there (if you have the late '99-'03 7.3L at least).

Personally, the risks outweigh the benefits IMO.

 

I just gave up on the hubs and will use them as manuals from now on. I would love to be able to flip the switch and have it done but it's never worked, on my 00 X or this 05 250. POS system fo sho.

 

Disagree with you.

Properly maintained, they work just fine.

Mine are ten years old and work every time I want them.

Preventive maintenance is the key.

Pop

 

Thanks for your reply. I'm loosing the vacuum at the hub. By looking at it. It seems to be the axle that pushes on the hub to make it work like a ball point pin. I can find no way to get the vacuum from the knuckle housing through the bearing hub. I was at the ford house today and payed 24 dollars for 2 yellow O-rings. I asked if the Vaseline came with it.

As far as the risks outweighing the benefits of changing the top end oil, when you have to have 8 injectors replaced at a cool 4 thousand dollars from ford, its worth a little extra time. Take a look at this video and tell me what you think.

POWERSTROKEHELP.COM - The Information Source for Ford Power Stroke Diesel Owners


Cheers

 

How do you do Preventive maintenance on a bearing hub seal?

 

When was the last time you had your hubs off to grease the needle bearings and shoot some grease through the ABS sensor hole? Grease on the stub axle shaft will help prevent that seal from developing a leak.

When was the last time you went through your locking mechanisms?

Understanding how the whole thing works will help, too. Then you'll know what to keep up with, PM-wise.

Pop

 

We discussed this extensively last year. Lemmee find the thread.....

Ahhh, yes! Here it is:
https://www.ford-trucks.com/forums/7...il-change.html

There's 182 posts in that thread, and there aren't any Cliff's Notes, so you'll just have to muddle through it.

Pop

 

Did I miss the answer to pilotsaunders question about how the vacuum gets from the knuckle hub cavity to the auto locking hub? I thought it came thru the stub axle splines to the diaphram on the locking hub. I don't think there is a hole in the end of the stub axle but I've been wrong before.

 

Thanks Pop's I stand corrected. The answer to your question is Never and I have 74k miles on her. Time to buy a grease gun. LOL.


Woody you are correct. There is NO hole on the end of the axle. Just a small indent. I think the frigging axle moves in and out and push's on the inside of the hub.

I'm trying to find out from someone who is smarter than me.

Cheers

 

That outer auto lock hub gets vacuum to it some how thats why it has an o-ring on it. I had mine apart last week when I replaced the ball joints, thats why I was wondering about it. My guess is threw the splines and maybe the needle bearing area.

 

My stub axle is pretty smooth going through the hub bearing, then splined as it gets into the locking hub. Where I see the vacuum line is way back on the knuckle. I don't know. I guess I will replace ALL seals and see what happens.What a Job. Will shoot grease on the bearing so Pop's won't get on to me anymore. LOL

 

You can buy generic O rings that will fit. Getting back to the air passage; There is a channel inside the knuckle that goes into the hub cavity but never goes into the stub axle itself. You can follow the air hole when you take it apart and it it pretty innovative and ingenious. I keep mine working well so I don't have to keep jumping in and out when I need the hubs locked/unlocked.

 

I have the hub off and you can move the stub axle around a little bit. Do you know if the seal is bad or should it move a little around the outer part of the seal? Where did you buy your o rings?

Thanks

 

I havn't bought o rings for a while. That axle will move around a lot if it isn't all buttoned up.