So my Excursion 7.3 has developed a new noise that I can't diagnose.

I only hear it when driving 30-50mph, under load at a steady speed. When I let off the gas and coast/decel it goes away. When I'm accelerating, I can't hear it over the engine.

It's a steady, repetitive whirring. Sounds like a bike tire out of round rubbing against the brake calipers when you were a kid. Sort of a fast rr-rr-rr-rr.

And from my seat it sounds like its coming from behind me and towards the right rear.

Thanks for any insight. Hopefully I can fix it myself. The only mechanic I really trust is an hour away.

Charlie

 

Certainly sounds like you are describing a right rear wheel bearing about to fail. There are lots of "suggestions" on how to troubleshoot if it's a bearing or not but IMHO the only way to know for sure is to pull one hub off and look at the bearings. If you are going to change them because you find they are bad also recommend changing your rear diff fluid at the same time. If you have a trashed bearing the carnage has probably contaminated your fluid. Could also be something in driveline like a U joint or in the differential.

https://www.ford-trucks.com/forums/1...r-dummies.html

 

I thought about the bearings. But wouldn't that continue to make noise while coasting?

What about a u-joint?

 

Man, i hope you find and report back your findings. If you google P.O.S. Howling sound...well, thats me. Been fighting the same sound for 2yrs. Started when turbo let loose. I'm thinking driveshaft area also..ujoints, center support... Sound comes on around 1200rpm, goes away around 1900rpm.

 

U Joints - IMHO can be the source of any rear end noise. Sometimes they click, pop, clunk, vibrate, growl, even heard it describe as a whine/whirl. So yes that's possible.

Wheel bearings - yes normally the sound will continue no matter what you do to the truck. But also remember that when you are under load vs not under load it also affects the stress being applied those bearings and although they still may be making noise you might not be able to hear it.

When mine started to go here are the symptoms I first noticed.
1. Had a what I would describe as a "whining or roaring" sound that started above 40mph. When I let off the go pedal and coasted all the way to stop without touching my brakes, the sound would gradually get quieter as the speed decreased, but there was an initial sharp drop in the sound as I let off the gas pedal. Took me awhile to realize I was still hearing the sound as I slowed down because that initial sharp drop made me think "at first" it was gone.
2. I had a vibration in the floor of the truck that started about 50mph.
3. Nothing I did to test it as transmission or engine or 4x4 issues changed the sound. I still had it neutral, locking or unlocking hubs or running in 4x4.

When they went completely #1 turned from an irritating whine/roar to a sound so loud you couldn't drive at 60mph and hear the passenger without yelling. Enough to make your ears throb on a road trip home. They were changed before the truck moved again and sound gone.

 

Much appreciate the feedback, Sammie.

Mine, as you have said, will completely fall on its face, if i let up on throttle. No noise to hear, but the slightest movement in throttle, would reveal its ugly face again. From 1200rpm - 1900rpm, its downright intolerable. At idle, nothing, 1st-3rd, i dont think i hear it, but 4th-6th, in those rpms range, forgetaboutit...

 

Welcome.

What about at 1400 RPM shift into neutral - sound goes away or not?

 

My noise is only while in gear holding steady speed in 3rd gear between 30-45mph.

I'm going to start by rotating the tires.

C

 

If the sound goes away when you are not in gear (shifting to neutral while driving at 40mph) then I wouldn't bother with tires. Tires don't stop making sounds because you are in neutral.

 

Tcase maybe

 

Check fluid levels of it and rear end

 

I found a local diesel guy to look at it on Monday. Probably just get the rear seals redone, and the rear fluid replaced.
C

 

your answer lies in your rear drive shaft, get it balanced and new u-joints and you shall be fixed. It may be fixed with just the new u-joints but i got mine balanced as well. problem solved.

 

I just went through this same problem on my 02 F-350 CC. I only noticed a whining or humming noise while on the throttle. After pulling my hair out and checking with many mechanics, It was determined that my rear pinion bearing was going out. I had all the bearing and gears replaced and the noise is gone. (I figured I would change the gear while they were in there since I had stock gear and I'm running 37" tires)

I'm not saying this is the problem but maybe another place to look.

 

Ya, mines only when on throttle. When replacing the p/s axle seal, i removed the rearend cover to drain fluid, and when that happened, i noticed all the gears in **** poor condition.

Was quoted 275 buks for driveshaft balance, new center support and ujoints. Thought, that wasnt bad.