I have a 2005 SCREW 4X4 with 127,000 miles on it.
Axel 19 = 3.55 Non-LS -> 9.75" ring gear

I bought this truck used about 4 months ago, it has always had a mild roaring noise that has gotten worse. To me the noise sounds like a bad wheel bearing. It is barely noticeable until about 25mph, and gets louder with speed. The noise oscillates and varies with speed as if it were associated with something that is rotating. If I put the truck in neutral and coast down a hill the noise changes pitch slightly but is still there. Also, it makes no difference whether I am turning or driving straight, and makes no difference if I an in 2x4 or 4x4.

Its sounds like it is coming from the rear (hard to tell) so naturally I assumed that is was the rear axle bearings. Thanks to Quintins excellent guide I was able to replace the rear axle bearings and seals and of course the gear oil. The old gear oil was pretty much black, and the drain plug was covered with a thick layer of sludge, I could see lots of fine metal shavings in the slidge but did not find any substantial pieces of metal in the diff.

Unfortunately, the new bearings made no difference and the noise it still there. I previously replaced the IWE so I know it has nothing to do with that. I investigated the front of the truck and noticed that the front diff has a small leak. There is some old(dry) oil staining all around the region of the front diff where the front drive shaft attaches. And is currently wet with oil at the bottom of the front diff but not actually dripping. I checked the oil level in the front diff and it was low, so I added about 1/2 a quart to bring it back to the level of the fill plug. But again this made no difference.

Does anyone have any ideas what could be causing this problem, or things that I should be looking at? I plan on doing a lot of long distance driving this summer and would really like to get this fixed before then.

Thanks

 

How is the gear clearance between the ring and pinion ? Too tight or too much will cause noise. Also 05's have carrier/pinion bearing troubles too. Try a search on rear end noise. Many threads out there on diff noises.

 

what about the brakes or wheels? I have had to try and find noises also. Does it do it going at idle speed, if so maybe someone can walk along or drive and you walk along and listen for it.

 

PS welcome to the site

 

Not sure about the ring and pinion clearance. The first time I have ever looked inside a differential was last weekend when I changed the axle bearings. I dont think it is the brakes, I had a good look at them and the e-brake when I had the wheels off. I could spin the wheels easily, and they did not make any unusual noises. I dont notice the noise in the cabin until about 20 to 25 mph. It might be noticeable outside at lower speeds, I would have to try that.

Is it possible that the u-joints are to blame? If it is a pinion issue, is ok to drive it like that or is a catastrophic failure likely?

 

Sometimes a unit will last 200,000 miles plus with never being touch and sometimes it just starts to fail. You have some high miles but I have also known others to go further without a hiccup. Your easy check would be the u-joints but I have never heard a u-joint make noise other than have too much play in it and you hear a clunk when going into drive or reverse. Then usually not too long after that it comes apart and you know this because you are pushing your truck to the road side or else where. I just thought that with the miles and you changing out the axle bearings the most likely spot is the main point of wear in a diff which is the carrier assembly. Since you varified the brakes while installing the axle bearings it is starting to narrow down. Also , noises do travel so don't think it can't be something else. Maybe have a friend ride in the back to try to get a better ear on things. Since you hear it in the truck at @ 20-25 mph you shouldn't be able to dump your friend out the back unless you want to. Or they can ride along side you if you can find the spot to do that in. I get I would get another ear on it and try to narrow it down. Noises can be a big PIA.

 

Thanks for the info Bara Mej, I am also now thinking that the problem may be in the diff. I pulled the drive shaft today to inspect the u-joints and they seem to be good. They all rotate smoothly and there is no play. The pinion shaft also seemed to be solid with no play. The only strange thing that I noticed was when I pull the drive shaft out of the transfer case a small amount of fluid dripped out of the socket, enough to make a puddle about 3 inches across.

 

yup that will happen when you do that. Try the friend in the box. Might just nail something down for you. You almost have covered it all in the rear.

 

I took the truck into a local tranny shop. It turned out to be a bad bearing in the diff. Not the pinion bearing like most others are having problems with but a carrier bearing. There was no damage to the gears so I had them put in a new bearing set. Cost me $997 but the noise is completely gone.

 

I just got mine out of the shop. Bad pinion brgs. My ring and pinion was ok, which I knew cause I had the cover off myself and checked the pattern and check back lash. 37 K and a known Ford problem. Glad you got it found and fixed plus you learned stuff about your ride. Some guys forget that even though it costs you some cash once in awhile you still learn from whatever it was. The only thing I forgot to tell you was you could have put the rear up on jack stands and listened or had some one back there listening. I did that to mine early on to verify it was the diff. Anyhow glad you are up and running.