rusticchef

When my truck idles it is fine, when in neutral and accelerate it is fine. When I drive in first, second and sometimes in third gear there is a loud whinning sound. Any body have an idea what it might be?

Bennyv83

So it only happens when accelerating?

Not coasting or cruising?

5 speed or auto? 4x4?

Crock Pot

Mine does the same, as do many others I have driven over the years. Sometimes the gears in the lower ranges are cut differently due to the higher torque loads experienced at low speeds, thus they make a noise that is not heard in the upper gears. Like the motorcycle guys say, a louder exhaust will take care of it.

heron2000

What my son is really asking is instead of a whine it is a whistle sound.

rusticchef

[QUOTE=Bennyv83;2746852]So it only happens when accelerating?

Not coasting or cruising?

5 speed or auto? 4x4?
Mostly only when accelerating. It's a 5 speed 2 wheel drive

Scott'sF150

IIRC 1,2, and 3, are straight cut gears. They will whine a bit.
I suggest however that you go to your differential, and check for any play in the pinion. IOW shake your driveshaft a bit. If the pinion flange moves excessively, it would indicate a worn pinion bearing.

If that's the case, a teardown and rebuild are in order.

Let us know how it goes.