Pimpinpete

Recently i had to drive through some pretty deep water and since then i have been having some troubles. Knock sensor codes started going off (fixed that), had a bad misfire that seems to have went away, and now this awful rattling noise. It happens idling in drive or park and it seems to be the exhaust rattling on something, or something is in the exhaust. The noise is coming from the passenger side around the collection of the header and if i press up against the header the rattling accelerates and becomes louder. Please any thoughts on what it might be because i just cant put my finger on it. Also where should my AC be draining? because it is landing right on the passenger header and is causing it to rust. Please any help would be appreciated, just want to feel reliable again after all this mess.. for some reason it wont let me link the video on youtube so here it is

Pimpinpete

Anyone?

Suburbazine

Broken weld on the collector would be my guess.

Pimpinpete

Headers are just 4 months old.. And there is no exhaust leak or anything. idk what would have caused that to happen

Infernohoe

Does the noise get faster when the rpms increase?

Pimpinpete

No, you can only hear it at very low speeds. Mainly just at idle. I figured out the problem with the ac drain lol, the hose coming off the drain was missing

GMC93

Have you removed all the factory heat shields for the stock exhaust? I've had rocks get stuck between the heat shield and the body before. Take a rubber mallet, crawl under the truck and start tapping on the exhaust and heat shields till you find where the sound is coming from.

Pimpinpete

Yeah no heat shields man. It has a full exhaust on it

Pimpinpete

Well i started hearing a humming noise around 30-40mph. Laid under the truck for awhile to try and see if anything was messed up down there. The front diff got water in it and the pinion seal is leaking. I dont mess with differentials so i took it to a specialist and should have it back by Thursday. Hopefully this fixes the problem but i still have not figured out the rattle yet.

GMC93

Should be heat shields attached to the underside of the cab and bed. Still would be there unless you removed them.