Trav-ler

My 09 F-150 makes a loud humming, buzzing sound from 5mph-25mph accelerating and decelerating. Something like a hydraulic pump pressure blowoff valve vibrating. Below 5mph it stops making the sound. Not sure if it stops making the sound above 25mph i just can't hear it over all of the other sounds. Could be the brakes but i don't think it is. The sound has the same pitch regardless of mph or engine rpm. Anyone have any ideas what might be causing this sound?

71_340

If it was my truck the first thing I do is accelerate up to, say 40 mph and put the transmission in neutral and turn the engine off. This way at least you can rule out the engine and any of it's driven components (alternator, etc.).


If you still have a noise it is in the axles somewhere.

Trav-ler

Hadn't thought of that to try and isolate the possible source. I will try your idea tomorrow and report my findings. Thanks!

71_340

At least that will be a start.


Also, if you suspect a bad wheel bearing it will change the sound as you turn the wheels, going around a corner because more of a load is placed on the outside bearing. For example if you turn right the truck's weight shifts to the left side.

Trav-ler

I did try turning the front wheels side to side and different brake pedal pressures while the truck is making its sound and rolling, but the sound holds at the same volume and pitch with no change until it stops sounding below 5mph. Which is odd. I cannot stop the vehicle and get out to search for it. The sound is a growling, humming, sound. It is definitely associated with something under pressure or being restrained and not being relieved or released properly.

Trav-ler

The sound stopped for awhile then started again the other day. Not certain but I think the sound may be generated by the driver side front wheel. I think the brake caliper may not be releasing completely?

Lethal Weapon

Sounds like your IWE (Integrated wheel end), or as some call it: your Hub.
BTW: I would NOT recommend driving & all of a sudden turn your truck off... a good way to loose your steering by it locking your steering wheel, and creating a potentially dangerous situation for not only you...but others as well.
Anyways...check your IWE. Just had both of mine replaced with the same type of low growling noise.

71_340

The steering wheel will not lock unless the key is removed; you would have to place the shifter in the "P" position to remove the key.

leveledgreengem

If you turn off your truck in Neutral, you will loose power steering and power breaks but the steering won't lock. It only locks when the key isn't in the ignition as an anti-theft mechanism.

leveledgreengem

Beat me to it!