Loud motor noise when it reach above 50mph Need Help!!

[NYC-X5]

Hi Guys

My 03 3.0 just past 50K, so far no major problem except replace one of the window regulator. Recently the alternator died on me and replace with a brand new one. After replace the alternator the loud noise comes when it reach above 50 mph and it really annoying the hell out of me. I got the alteranator from alternatorpro.com, very good price and is Bosch alteranator. I don't know if is the new alternator that causing the noise or something else. Before doesn't have this kind of noise at all, and now is like I am driving an old truck and it really bothering me.

[admranger]

Where, specifically is the noise coming from? Engine compartment? Is it a whining, flapping, clunking, or ??? type of noise? Maybe you could record it and post the sound file.

You are implying it is speed sensitive. If you are sitting, not moving, but rev the engine, does the noise appear? If the noise does not appear at a specific rev range, but only a speed (moving) range, it isn't the alternator. Look for loose underpanels or some debris you may have lodged in the vehicle underbody.

[LeiZ]

Fairly good explanation.

Originally Posted by admranger

Where, specifically is the noise coming from? Engine compartment? Is it a whining, flapping, clunking, or ??? type of noise? Maybe you could record it and post the sound file.

You are implying it is speed sensitive. If you are sitting, not moving, but rev the engine, does the noise appear? If the noise does not appear at a specific rev range, but only a speed (moving) range, it isn't the alternator. Look for loose underpanels or some debris you may have lodged in the vehicle underbody.