I changed my front axle u joint this summer. Now that winter is here, I used my 4x4. I have found that there is a whining noise while in 4x4. It goes away when in 2wd. This noise was not there prior to changing the u joint. And it sounds similar to a wheel bearing noise. Any ideas?

 

You gotta post way more details about your truck or we can't help you nearly as well. Because you failed to be specific about it, I'll just give you the general experience I had with this: Stuck vacuum hub.

 

My truck is a 2006 F250 Lariet crew cab 4x4. It has 230 000 km on it. This past summer I changed a badly seized u joint. When I changed the joint, I also changed the seals for the vacuum hub at the same time. I did try the 4wd in the summer, but it was in a field, not on the road. Now that winter is here, I am at 60km/h, or 40mph in 4wd and I am getting a noise similar to a warn out wheel bearing. But I am only getting the noise while in 4wd. The truck isn't pulling to one side or another, actually drives nice and straight in 4 wheel or 2.

 

My truck is a 2006 F250 Lariet crew cab 4x4. It has 230 000 km on it. This past summer I changed a badly seized u joint. When I changed the joint, I also changed the seals for the vacuum hub at the same time. I did try the 4wd in the summer, but it was in a field, not on the road. Now that winter is here, I am at 60km/h, or 40mph in 4wd and I am getting a noise similar to a warn out wheel bearing. But I am only getting the noise while in 4wd. The truck isn't pulling to one side or another, actually drives nice and straight in 4 wheel or 2.

 

Quick question. Do you run the 4 wheel once a month to keep the system in check? I know it is recommended practice which I am sure many of us have slacked off about it. You should run the 4 wheel High and low once a month to keep things operational. Of course not on a dry paved surface.

If you left the hubs in auto there could be an issue with the vacuum lines that run the system. I would suggest to turn your lockers from auto to manual. Then try again. If the noise goes away, you have narrowed down the issue to a control function for the 4WD. It could be a damage or disconnected or even a mis connected line with the front hubs. It could also be one of the hub locks could have failure. I know several on the forums have changed the hubs out to a true manual style lockers. The only pain is on the ESOF (switch on the dash) you have to lock them first before going to 4 wheel H or L. That's where I would start first.

 

Correct me if I'm wrong here - Vacuum hubs with a selector don't go from "auto to manual", they go from "auto" to "locked" if I'm not mistaken.

 

Nah Ford just decided to install DCTs in the hub locker now! LoL. Seriously yes it is Auto and Lock. I stand corrected.

 

Turns out that the truck wasn't fully engaging into 4x4. I took the truck over to the marina to try out the 4x4 in the deeper snow. low and behold, I was almost stuck. tried to lock the hubs, but no change. Tried 4wheel low. It wouldn't go into 4 wheel low. the light wouldn't even flash like it wasn't even trying. I unlocked the hubs and put in and out of 4x4 a bunch of times. just as I was about to give up, it decided to fully engage into 4x4 high. I drove around the marina for a little bit and tried 4x4 low. no problem.

lesson learned. As mentioned earlier by FordmanNJ it is a good practice to run the 4x4 system at least once a month. for me I try to at any given time. The problem is finding a place to use 4x4 in the summer time.

Thank you to all who have tried to help. All input is always welcome

 

If you have any non paved roads around you that is all you need to run the 4wd safely, you just need a loose surface for the tires to slip a bit. If you manually lock the hubs in and drive around in 2wd that will keep the axle lubed up but you will still need to shift the transfer case in/out of 4wd to keep the shift motor working.

 

Yes I have thought of that before. Finding a gravel road in this area is slim to none now. That is why I thought about going to the marina. The only down fall is that I can't really pick up much speed. I will venture to find different options, so that I don't experience this issue again.

 

There is no problem with putting it in 4x4 on pavement as long as you are going straight.

 

Funny story about "off roading" locally. A couple of years back, I was checking on the 4WD since it was not in use for a couple of months and the truck was sitting for a bit. Where I live, there is a large park in town. Towards the back of the park there is unimproved parking area for overflow and back sports fields (soccer, lacross, etc.) So I take my truck down there and make sure no one is parked in the area before I tested the 4 wheel. The parking lot is a combo of millings, crushed stone of dirt. Since no one was parked in the lot, I proceeded to perform figure 8 patterns to function both steering directions. I also pull straight and perform reverse movements. Once I was done with high I shifted over to low. I guess I kicked up some dust or was spotted. A local town police officer came in the back to see what I was doing. However I was just finished up and heading home. He pulls down the road as I was leaving and he flags me down. I asked what's up and asked if I had seen any thing nope I was just in the back testing my truck's 4 WD and this is only local area I know that is park enough with out pavement to test on. He said OK and asked if I ripped up the parking lot. I said no I was very ginger about it. Good thing I was going out the front instead of another "back" way out (access roads) which technically off limits except during certain events. I think the town finally installed gates on the roads to stop people from driving them since people also use them for walking and biking. The access road is kind of fun for the area since it has some turns, straights and dips. I know the police love to drive it every so often they do a patrol of the park.

So the OP figured out the hubs needed to be worked a bit to get going? Do you have some other lingering issues with the system?

 

Question about hubs on trucks with unit bearings. How are they lubricated (as opposed to my 1980 with the shared wheel bearing grease)

Old style that shares wheel bearing grease