Hello everyone,

I have 1999 F350 7.3 Crew Cab 4WD. I took it on a 4 hours trip towing a trailer to haul a small tractor on it. after 3 hours of driving, I started hearing grinding and metal chewing sound coming from the front axle or close the wheel hubs. It was awful, terrible, ... you name it!!! I had to continue or I will lose the $5000 tractor I paid for already. The sound was coming for 1-2 seconds each 500 feet or so. It never stopped or changed. I pulled over to see what's going on and found the following:
1. Left shock is leaking badly
2. Right locking hub is gone (not sure if the truck had one before). I bought this truck last year, but I never had to use 4x4 and I know the 4x4 motor by the transfer case is missing and the nipple on the transfer case is set to the 2wd position so the front drive-shaft does not turn.

I took the front shock off and continued to drive without it, the noise did not go away.

I pulled over again and this time I noticed that the dust cover on each end of the front axle is missing too. I have never worked on these axles before, but I jacked one side, and sure enough, gear oil was leaking from the other side. I took the plug off the front differential and stuck my finger in it. I felt a creamy brown-greenish stuff in the differential. The consistency is like mayonnaise or thin peanut butter. I put the plug back on and went to pick up the tractor because I did not want to miss it fooling around with the truck on the highway.

The truck made it there and back (almost 5 hours total after the break down). The sound never stopped every 500 to 1000 ft.

After getting home safely, I took the other locking hub off, and took it for a test drive. I did not hear the noise, but now my right brakes are locking.

I took of the wheels and saw that the retaining snap ring (C clip) for the front axle on the right side came off by hand. I took the washers behind it off. Took the calipers and brackets off. I have never done front axle rebuild. I am not sure what has been damaged and what's still good.

Right of the bat, I know, at least, I need 2 shocks, one brake caliper and pads.

My questions are:
1. Is it possible to take the front axles off on both sides and make it 2wd for now until I have the money to rebuild the axle?
2. Could I use the same hubs? or they are most likely damaged and how to tell?
3. How to tell if the differential is damaged/needs rebuilding?
4. How to tell if the axles/spindles are damaged?
5. Is there a step by step tutorial to rebuild the axle with all seals, bearings, ...etc? How hard is the job for a hobbyist? I do most of my repairs myself, and I was lucky at 36 years old, I never had to rebuild a differential.
6. What else I might have damaged in the process of driving it that long with the noise? How do I tell if I did?

I know it's a very long post, I apologize for that, and I hope some of you guys have time to advise and help.

Thank you!!

 

I don't know any of these for sure because I have never done it myself. I would think you could pull the shafts and run it. But if the hubs are unlocked the front drive shafts shouldn't be turning anyways. The noises you are hearing might be the unit bearings that are toast. Sounds like the front axle needs a fluid change for sure. Unless there is internal damage noiseable these axles are pretty tough. 75/90 weight oil if memeory serves me correctly. For difficulty of the work I don't think it's bad at all. I have had my front end apart many times. Have gotten to the point that I can swap out a unit bearing in about 35 mins.

Hope that gives you some direction.

 

Thank you very much. I wanted to ask is there a way to replace the unit bearing? I did some search and it seems like the hub is not serviceable on these trucks. You have to replace the whole hub if the bearings fail. There are 2 bearings in the hub. The first is the wheel bearing, I guess it's called unit bearing too. And the second is the needle bearing that goes on the back side of the hub.

 

Here is some help on this, Sam. I haven't had to touch mine yet so I'm not able to give any first hand into on it. There are more pages here on the front hubs as well.
[URL="http://www.guzzle7pt3.com/nblube.php"]

 

Sam1980,
The seals in the end of the axle where the drive shaft comes out are just dust seals. Further in is where the actual seals live. The dust seals on these trucks are more often than not shot.


Below is a link to a how to for pulling everything off down to the ball joints. I include it because it has good pictures and explanations.
The main bearing is replaced as a unit, no way around it unless you convert the whole axle and that is expensive. The needle bearing in the back can be replaced separately if that's all that's wrong with it.

Ford Super Duty Ball Joint Replacement Procedure - Superdutypsd.com

 

Sounds like there are several issues going on.

If you are leaking oil from the axle tubes then the inner oil seal is a goner on that side. You have to pull the entire carrier out of the case to replace them (which also means pulling the hubs to get the axle out). Lived that dream.

The hubs are unitized bearings. The weakest part is the inner needle bearing as it cannot be lubed again after the hub is installed. I had an intermittent grind/hum (like going over the grooved pavement on the shoulder to alert you that you are leaving the road or when the freeway is ending) that I put off for too long. My needle bearing on the passenger side dried up, came apart, and wedged themselves in all sorts of places. I ended up damaging my hub, stub axle, auto-locking hub, and inner oil seal.

The missing dust covers make me wonder what the previous owner did to the axle and if it's even the original axle.

 

Normally the bearings in these trucks are replaced all as one. That's how they sell them.

 

I am having the same noise on the driver side of my truck. Expect it has a brand new bearing. Not quite sure what is going on there. But it is annoying for sure.

 

The hub bearing assembly is unitized and is a wholesale swapout if any part of it goes bad. Better for production costs but not our wallets down the road.