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I need help guys. I'm at my wits’ end.... I have a super loud gear-type whine coming from what I perceive as the front end (or somewhere underneath me) starting at 25mph and above, but only when
I am accelerating.

The sound builds from barely perceptible at 20mph to loud at 25 mph and louder as speed increases and then the sound level stays same. When I let off the gas, the whine instantly stops.
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It’s louder than the damn engine at 30-50mph.<O</O
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This is while in 2wd, front hubs unlocked. I haven’t tried is in 4wd mode but I cant see how that would make any difference.<O</O
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It doesn’t matter if I have 2000 pounds of stone in bed or am riding empty.

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I thought the center support bearing was the cause, but after changing it, the sound hasn’t gone away.<O</O

The truck has 198k miles on it, brand new tranny which I installed myself.
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Could it be something I did during the tranny install? I am sure I greased the splines before installing the FORD remanufactured tranny.
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There was a whine before the new tranny went in, but it’s gotten way worse in the 500 miles since I installed the tranny. I dont think they are related.<O</O
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Could it be power the steering pump? A pulley bearing? Front and rear wheel bearings are original but bad bearings make a groaning/roaring noise. This is more like turbo whine, but much louder and slightly deeper.
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Any thoughts would be appreciated!
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Lex<O</O

 

I have the same thing in my truck. What the previous owner told me was the Ford house told him that it is coming from the front differential. That when installed the first time, if the gears are not lined up correctly, that the noise is heard. I was told that it poses no problem to the vehicle, and is just an annoyance to the driver. I'm interested in what others have to say on this.

 

But if the hubs are not locked, the differential shouldnt even be turning. No?

 

I don't have an answer for that. I'm still wet behind the ears with this truck. Not sure how the hubs, differential and transfer case works on this truck.

 

I am in a similar situation. This is not only my first diesel, but my first proper truck. Learning as I go!

 

So I just remembered exactly what the owner told me. He said the problem was the alignment of the pinion gear and the pinion. He said when they install that, if they don't set the angle just right, it will whine. I think it is a common FORD problem for our year truck (mine is also a 02 F-350 4x4 7.3).

 

But why would it be making noise if the truck is in RWD and the hubs are unlocked? The gear should not be spinning.

 

subscribing...Man, i hope we figure this out....

here's my thread...

https://www.ford-trucks.com/forums/1...ing-sound.html

 

I read your thread and dont believe we are experiencing the same issue. My buddy who is a mechanic told me he thought it was gear-related noise. He works mostly on passenger cars however so said he wasn't confident. I also think it is gear whine or maaaaybe bearings. Its not a whooshing noise and its not RPM dependent, but rather is speed dependent. Comes on right at 25 mph and only when on accelerator.

Thanks for responding my friend.

 

Well I finally have an answer to this dilemma. I brought the truck up to the Ford dealer and asked one of the mechanics I deal with for business accounts to take my 7.3 for a drive to diagnose the gear whine. At first he was stumped even though it was loud as heck. So he brought another seasoned mechanic in and all 3 of us drove around.

They speculated on tires or gears. Then we put the truck up on a lift, 4 wheels off the ground and put her in gear. With a mechanics stethoscope we listenened to the pinion bearings and axle bearings in the rear axle. WOW...super loud. It was loud even without the stethoscope.

I suppose this was not the standard noise that a failing pinion gear makes....hence they were both unsure until they used the stethoscope.

YAHOO! I have a diagnosis!

 

Never mind.... saw your other post.

Nice job finding the issue. So what's next rear end rebuild? How much did they quote you for that?

 

i didnt ask. I would never ask the stealership for work on my personal vehicle....too expensive.

Im considering whether to repair myself or switch out the entire axle for a used axle from the junkyard...

I will let you guys know when I make my decision and share any good info.

 

Did you pop the pumpkin yet to see what's going on?

Thanks for getting back on this... others can benefit from your experience.

 

Hey Tugly,

I assume you mean the differential cover? Nope havent done a thing yet.

Am working on another vehicle before I can get to the 7.3.

Will keep ya'll posted.

 

I just had the pinion bearings relplaced. Truck is a lot quieter.