First let me apologize for the length of this post, and say that you all are wonderful. I have been reading this forum for months as I have worked to my X and finally decided to join and see if anyone here could help me with an issue that has me and my mechanic stumped. I can't tell you all how many times this forum has helped me while working on this truck.

I bought this X in May of 2012, I used to own the same vehicle back in 2000-2003 and always regretted letting it go. It's a 6.8L V10 2000 with 77,000 miles. When I got it he engine and interior were in a great shape but the under body looked like someone had it parked in a DOT salt barn for years. Major rust that included the frame rails, axle housings, stabilizer bar and hubs.

Since purchase this is what I have had done to vehicle:

Replaced front and rear axle housings from stock to a set from a 2002 F250SD, these were both serviced before they were installed and gears/pinions serviced and checked with new seals installed. These included wheel hubs and rotors, which were turned and are sound. New hawk pads were also installed. Had them remove the rear stock block because the rear would have been too high (above front by 1 1/2 inches) and had them shim the rear to set the ring and pinion angle.

Replaced leaf springs with Pro Comp 22410 front and 22415 rear with new mounts.

Replaced the front sway bar (it was broken in half) and added a rear Hellwig bar.

All new ball joints, and all steering arms, adjustment sleeves and steering stabilizer.

New KYB shocks all around.

Drive shafts were removed and re-manufactured by a shaft shop and balanced and reinstalled.

After I got the truck back I installled a new gear shift and shifter tube assembly to resolve some play in the shifter and steering wheel, and a new serpentine belt to get rid of an irritated squeak. I also tightened the gear box about 1 1/4 turns.

When I first got the truck back after these things were done, I had a pretty good vibration at 45 mp. After talking to my mechanic he had me take it directly to the Rack and Axle shop, thinking the Pinion angle was off a degree or two. They checked the angle and it was "spot on" but found the rear drive shaft was a 1/4" too long so they pulled it off and shortened and reinstalled. After this correction 90% of the vibration at 45mph went away.

The next week I got it up on the Highway for the 1st time and noticed a humming sound at speed. Was gradual increase with speed and couldn't pin point a certain speed it started. My feeling was it the sound was there from start but just wasn't loud enough to really notice until you go going on the highway.

After doing some reading on this forum and several tests drives I came to conclusion it was probably my front needle bearings. The sound would disappear if I locked the front hubs but stayed in 2WD. So back to my mechanic and had him pull the front wheel hubs and replace the needle bearings and service and re-pact the wheel bearings, I also had him flush the power steering and fill with Mercon V. He also rotated my tires but they forgot to reset the PSI in the tires so I did that later that evening setting the front to 50 and the rear to 60. BTW this truck has some corroded rims which are next in line to replace and has Geo Trac 265 75R 16 tires on it.

Got the truck back and all the vibration below 50 was gone and the general humming sound was gone. Two days later took the truck back up on the highway and noticed a much louder "humming/roar sound" that begins at exactly 57 mph. Definitely is a rotational sound of something spinning and not spinning right! Almost sounds like you are trying way too fast with your hubs locked or in 4H. So to narrow it down I tried the following things:

Got up to the "roar" speed and put it in Neutral - no change
Locked hubs in - no change
Drove in 2H hubs locked and unlocked - no change

My first thought when I heard this sound was out of balance tire since they did rotate the tires and I haven't had them balanced, because I have new rims on the way here and plan to have the balancing done on them. But it not associated with any vibration just this roaring sound and really does not sound like an out of balance tire sound. It sounds drive shaft or axle gear related, but all of these are recently serviced or new. The sound is at high speed only starting at 57 and continuing up to as far as I've pushed it which is 67 and does get louder the faster I go. Maybe a very slight shimmy associated it with above 65 but nothing violent. I can feel this roar under my feet in the drivers seat, as soon as I get off the load and drop below 57 it stops.

I am currently working on sanding down the remaining run on the under body with an angle grinder and various other items, treating, sealing and top coating with KBS rust products. I did the front wheel wells this weekend.

Again I apologize for the length of this post and if you took the time to read it I really do appreciate it and any thoughts you may have on what my "roaring" sound may be?

 

So now locking the hubs in while in 2wd makes no difference where before they repacked the bearings it would? My first though after reading your rust statement is potentially a bad u-joint. You could try removing the front drive shaft to see if that changes anything. Has the xfer case fluid been changed?

 

U joints are brand new were replaced with the drive shafts were re-done but I agree it sounds like a U-joint sound to me. Wondering if they are too tight. Turning them myself they feel sound and I did check how they felt and made sure they wouldn't hand turn with hubs locked and vice versa.

No transfer case hasn't been touched. Could you get that kind of sound from there?

Thanks for replying. I'm going to kidnap my mechanic this morning and we are going for a drive and listen session.

 

Check t-case fluid and make sure it's in 2 wheel vice 4 wheel. The t-case
Could be in 4x4 high, but front hubs unlocked. That would make the front driveshaft spin and potentially cause a roar at higher speeds

Did it act funny when you locked in the hubs? Pull, buck, jerk like it was in 4x4?

Def wierd

 

I'm not all that mechanically inclined... but I have seen a rock stuck in the tread make some weird sounds. Sometimes it's stupid little things.

 

My 2000 ex 7.3 4x4 was doing the same thing. It turned out my ESOF hubs were frozen and only partially free. I pulled off the hubs as well as the wheel hub units and replaced both. So after new warn manual hubs, new wheel hub units and greasing the slip joints with the ford Teflon grease it solved my issue.

 

Weird indeed, what are the odds that I had a bad needle bearing, which is now fixed that elminated the lower speed roar for the most part, then get a hub bearing go bad 2 days later?

No it doesn't act like it's in 4H with the hubs locked, no steering changes etc. Is there anyway to confirm its not in 4WD other than gut feeling on how a truck should feel in 4H. Because that is what it sounds like to me. I sounds like you are in 4H but going way to fast be in using 4H. But I'm just a mom with a truck and have some knowledge but don't know how to tell "for sure" if it's in 4H with hubs unlocked. I can asure you it's not set to 4H but I know you mean it's in 4H even though it isn't set that way. Can I tell if I have my hubs locked, any test to make sure 4H isnt' engaged?

Did go kidnap my mechanic this morning and took him for a test and listen, and he thinks it may be a wheel hub bad on the front. He is taking it tomorrow and hooking up listening sensors and then is to drive and listen. Hesitant to foot the cost for hub assemblies since what is on there are recently replaced, but they were off a used F250 so it's possible my replacement hubs came with issues. I'm going to pose that possibility to him on the 4H being engaged and see what he has to say. Good news is he did say he would change them for free (labor) I buy the part.

I will keep you posted on what I find out.

 

alternatively, one of your hubs could be engaged/stuck. that would cause the front axle to spin and the front driveshaft to spin...which is directly underneath your feet


that is the most likely culprit


look at the front hubs and see if they are locked or unlocked

here is a "automatic" hub from the factory. make sure the markers align with the "Auto" position

 

Mine isn't auto - it's Locked or Free. Mine are free and the u joint rotates freely in my had with them set to free. I tested the transfer case setting yesterday and with the hubs set to free and the switch set to 4H the axle will not turn when I try to twist it, same in 2H but with Hubs locked. So I'm fairly certain that my 4WD is engaged when it's supposed to be and NOT engaged when it's not supposed to be. At this point I am leaning toward it being a bad front bearing unit. After the sensor listen test that's happening this morning I should know an answer for sure, well I hope. Probably doing both front hub units this week, and may go ahead and put in a redhead gear box and pitman arm which were the only two steering components that were not replaced originally. New rims will also go on next week as well as a transfer case fluid change and service. Then everything in the drive line and steering systems are new - all that leaves under the truck would be transmission and I'm crossing my fingers. If it still hums after that - well I'm probably going to find the nearest cliff and a good heavy brick Good thing this truck isn't my daily driver - it's been up in the air more than it's been on the ground since I got it.

 

Unfortunately a lot of rotating parts can make sounds similar to what you are describing. The transfer case fluid - quality and level is critical to it operating correctly. If the fluid is not a nice red color (Mercon or Mercon V) then it could very well be the issue.

Hubs can certainly go out -but they typically don't just go from silent to roaring very quickly unless allowed to stay in standing water for a long period of time.

 

Update on this......

My mechanic did the drive and listen test and he is fairly certain that the sound is coming from the front passenger wheel hub. So 2 new hub units on order and those will go in next week. I am still not convinced but since he's doing the labor on this for free and I'm just buying the parts I'm going to go ahead and do both front hub units. Miles warrant the change regardless of this sound.

Since I'm still not convinced my drive shaft is functioning properly, even though the place that did the reman and balance on it; checked it a second time. So I decided to do a little test today. This truck has a backup camera which I installed on the rear license plate, I took it off today and with a few zip ties and a video extension cable ran it to the side of the truck and mounted it just to the right of the rear axle where it connects to the transmission. Just went for a test drive but it's a reallly bright sunny day here so the light coming in the other side of truck was too intense to see much, but do now have the camera showing me the axle spin as I drive. About dusk I am going to take it for another spin and get a good look at the axle in motion during the "roaring" sound. Will post later what I find out.

 

That's not true. One locked axle won't cause the front drive shaft to spin. It will cause the opposite unlocked axle to spin in the opposite direction at the same speed.

 

You would know it if it was in 4wd on the pavement.

 

Well I'm talking Rear Shaft right now anyway, but for the record if I lock in 1 hub and manually try to turn the front shaft it "does not turn" so although I wouldn't try it on the road, with manual locking hubs if you lock in just 1 hub (or had 1 hub not unlocking properly) it would cause the front shaft to rotate. That being said I have already determined the front shaft is not the problem because with the hubs unlocked and in 2WD it is not moving well creeping around a bit with the motion, but it's not spinning under any load. Used the backup camera mentioned above and some zip ties, now have the camera mounted to watch the rear axle in motion and will be doing another test drive when the sun goes down a bit. The sound could be from the rear axle even though it appears to be under my feet, we are talking about a few feet further back and it seems sounds are hard to pin point in a truck this big.

 

Locking only one hub won't turn the driveshaft while going down the road and turning the front driveshaft while driving will turn an unlocked axle but won't supply any power to the road. Spinning the front shaft only comes from the t-case or both hubs locked, or both.