So, I've got an '03 F150 FX4 model, 4x4, 5.4 liter engine, and about 140,000 miles on it. Lately, I noticed a slowly growing (in volume) sound coming from under the hood. I have been told it might be an exhaust leak, however; I am not so sure. Anyway, this sound has become higher pitched, and is continuing the make the noise at higher speeds, as it used to stop around 40 mph. The sound is a high pitched whining type of sound, maybe a little 'winding', too. As I accelerate, the sound follows, becoming louder and higher pitched. If anyone has had this problem, or knows what it might be, I would greatly appreciate the feedback.

Thanks,

Nick

 

Hello, "...it used to stop at 40 mph..." makes me think it's a bearing which has lost its last bit of lube. Slacken or remove the accessory belt and start the engine briefly and see if the noise goes away. An idler bearing will feel rough. You might be able to get the noise to change pitch by hitting the brights and power window switches at the same time-that would point to an alternator bearing. Try turning the steering wheel when it's making the noise. It could be the power steering pump. Kira