R6Ivy

Im prettysure its not pre-ignition knocking. Plus ive ran 93 since day one. But thank you I will have to check this thank you very much.

Hi, I'm pretty new to this website. Came across it when I was looking for an answer to my problem . . . I don't know too much about trucks.. cars....4 wheel vehicles. I just bought this 06 crew cab 1500 silverado 4.3L had about 80k miles on it. I actually noticed the sound when I was test driving it from the dealer. Now it has about 101k miles and noise is still the same. it makes a rattling noise, almost like a metal noise at LOW rpms only. Doesn't matter if its 35 or 75mph. Have to be cruising like slight amount of acceleration. Sounds like its coming from the engine.. I checked a bunch of forums all saying different things. my truck is stock, as far as i know.. one of the forums mentioned it could bea bad alternator, but I have no clue. any help? Sorry I'm a complete noob. Ivy