Hello,

I just bought a 2003 F150 XLT (F4X Off Road series) and noticed that there is a humming noise that starts when I accelerate between 35 to 50 mph. Whenever I press the accelerator in that range, the humming begins and when I let-off the gas and coast, the noise stops. If I put it in neutral when I'm rolling in that range and hit the gas, I don't hear the noise. The humming seems to be coming from the underside bed area of the truck the best I can tell. Does anyone know the cause of this humming noise?? Thanks for your help

 

Hi and welcome to the forum

How many miles on the truck?
A bad U-joint could be the problem. Usually if it is it will also have a high frequency vibration.
It could also be bad bearings in the rear end.
It will probably take a trained ear to give you a better idea of the problem.

 

Thanks for the response. The truck has 52,000 miles on it.

 

Do you recognize the tune? Maybe hum a few bars for us? If so, we could maybe track it down better. :-)

Just kidding ya maddog.

 

Yeah, i have the same noise coming from my ford. Did you get the truck looked at yet and if you did could you tell me what it was. thanks.

 

I had it looked at today and it's either the pinion gear and/or a bearing going bad in the rear-end.

 

do you have any idea how much that would costs. i mean the noise really don't bother me, but i would like to get it fixed before something worse happens. Hey thanks for the reply.

 

I was given a beginning estimate of $800 and it could go up from there, dependant upon what they find once pulling the rear end.

 

Anyone replace a bearing and/or pinion gear themselves? How bad is it?

 

i have the same thing wrong with my truck. I am going to try to dig in a fix it myself. Ill let you know how it goes

 

Welcome to the forum hardrock47

 

Your problem sounds similar to my post "Differential or tire noise". My truck has a similar sound. I heard from a mechanic friend that ford had problems with the differential making that sound and that there were some ford service bulletins on how to correct it. Has anyone else heard that? He had his gears changed under warranty. Let us know what the fix is, and how much it costs.

 

The humming noise is caused by the pinion gear going bad in the rear end. I heard it's pretty common with Ford. It cost $1,100 to have the dealer fix it.

Maddog