So at 260K miles I have a bit of a whine going that seems to relate to RPMs and I suspect it is in the drive shaft. I have a very slight leak at the power-steering pump and topping that off makes one whine go away but the other does not.

It does feel like there is the tiniest beginning of a bit of play in the shaft but it is not something I am that familiar with.

I took it up to a very good shop I like in Alamance County, NC, this morning, where I am working some this week. If you need a good Super-Duty mechanic up around that way I highly recommend Gary Moran there on the Orange/Alamance line out in the country.

Anyhow he thought my rear brakes are down low enough that they might be sticking just occasionally enough to put extra wear on the wheel bearings. So the first step is to fix up the rear brakes and then find out what is happening with the bearings in the back. He suggested that once you start in to those bearings one might as well do all of them at once.

Once we had figured this out this morning things got pretty busy in the shop and I had to get back on the road for other errands myself before I figure out some of these questions:

So my question is, how many bearings are in the rear drive system? I would imagine there is a set at the end of the drive shaft going into the pumpkin, and perhaps one more set for each wheel? These would be separate from some of the ring gears, etc., that make up the guts of the pumpkin?

I guess I am just trying to wrap my mind around some of the parts costs to put in some new Motorcraft bearings. I do like to fix things right for the long-term on a vehicle with an engine as durable as this one.

 

First of all, I must say that I don't see why brakes hanging would have any affect on wheel bearings, they could I suppose, but it would be a surprise to me. Also drive shaft play would have something to do with U-Joints or possibly the pinion bearing, but not wheel bearings. The noise you describe could be differential gear noise. In which case cleaning and inspecting the rear differential would be a good start (look for metal filings, and wear on the ring gear). A very good write-up on this is at Welcome to guzzle's Ford PSD Web Pages

If the brakes are worn, I would suggest doing them yourself. I recently did the rear brakes on my F-350 Dually, it is not that difficult. I had to remove the hub and axle shafts to replace the rotors (which you may not have to do), this included wheel bearings. The service manual I use is online ALLDATAdiy.com :: Leading Source of Diagnostic and Repair Information (I really like it by the way), anyway it said that the wheel bearings only need to be replaced if they are worn.

7. Inspect the bearing races and rollers for pitting, galling or erratic wear patterns. Check the rollers for end wear and replace as necessary.
1 A typical new bearing roller.
2 A worn bearing roller.

The picture didn't copy but you get the idea.

At any rate if you decide to do/have done the bearings, there is an inner and outer wheel bearing on each hub, and the axle shaft bolts to the hub. It is a fairly easy job to do, but there are a couple of special tools you would need. The cost of the 4 new bearings and 2 seals from Ford would probably be in $100-$150 range (much less at NAPA ), depending on which rear end your truck has .

The bearings located in the differential I know nothing about, but maybe this will give your thread a bump to where someone more knowledgeable will chime in. Or maybe in the time it has taken me to try and make sense out of what I think I know, someone has already given you the answers you need. In either case I hope you get it all taken care of.

 

The pinion bearing is what I was thinking might be making that whine. The U-Joints seem good to me. That does make more sense that a sticky brake pad shouldn't impact all the way to that. I think my mechanic and I were talking past each other a bit too quickly this morning.

I do really look forward to the day I have a garage and the jacks and the free time to do a project like this myself. Right now though we are living and working one the road in the cold (I am a tree planting contractor, an ugly business competitively) and am also the only transportation for a number of people. Learning new systems to repair myself just won't make it to the top of my list right now. I bought some friction modifier at the dealership but haven't had the energy after work to open the differential myself.

And with several employees riding in the crew cab I know I could use the extra stopping power of the rear brakes, untouched since I bought the truck two years ago. (Front brakes in excellent shape, I did get to turn a few wrenches on those with a pro friend helping). They have been on my mind to update for some time but a lower priority than the money I just put into the second front

It does sound like these are quite different than the front, with the sealed unit bearings, and that is good news.

So now I am curious about the pinion bearing and how challenging that might be to replace.

 

I'm not sure how big of a job the pinion bearing would be, I think it involves gear lash and preload stuff, but I'm not sure. I think I would leave that to a pro. The pinion seal is an easy job though.

But again, for a whining noise I would have the differential cover removed and the gears inspected. At the very least, check the fill plug which is magnetic, for metal filings. I would do that before adding the friction modifier, in case you need internal differential work done, so that you aren't wasting money.

 

well it was typical good news / bad news

the brakes needed a complete do-over but I knew that. had put my $ into the front end as a priority and it was time. the wheel bearings were fine.

the pinion bearing, however, couldn't just be covered with grease to get through another week or two. one of the sleeves on the bearing was about to shear through and Humpty Dumpty couldn't be put back together. the good news is no damage to the ring gear; in fact my mechanic says he has never replaced a U-Joint on a Super Duty nor had to do anything besides the bearings. Quite different from the differential on a Z71 that goes out every 100K.

there had been that slight whine to the drive shaft ever since I owned the truck that had recently become a little worse. I felt bad that I hadn't changed the fluid in the differential yet but my mechanic thought that would have just given me a false sense of security while the bearing would still be overly worn at 260K miles. nevertheless I would suggest to anyone reading this to go ahead and do that, there was a very good thread on here for it about 6 or 8 weeks ago.

the bad news is that on Friday afternoon his parts delivery guy brought the wrong part. 5 of his 6 possible Motorcraft suppliers in his area were closed by lunch time on Friday. so we are stuck in a hotel for the weekend and I'll lose two days of production Monday and Tuesday while we move the parade to a new job and stage materials to it and this really hurts everyone.

 

My 2002 4x4 with 195k and automatic (brand new tranny) has a very loud gear whine / moan starting exactly at 30mph. This was present before the transmission replacement.

It gets louder when accelerating and then fades above 50 mph....maybe due to other noises overpowering it or it actually subsides...just not sure.

In other words the noise is louder when accelerating, above 30 mph, as opposed to when coasting or decelerating.

I started adding 2-stoke oil and Diesel Kleen to the fuel and the engine is sooooooooooooooooooooooooooooo much quieter that I can really hear the whine now...its really quite loud and prominent.

Does this sound like rear differential whine to you guys?

I feel like its coming from the rear but its hard to tell. When I had a cap on it, I felt more confident that the whine eminated from the rear...without the cap its harder to pinpoint the location.

Thanks for your thoughts.