I have a 96 12 valve Cummins that I purchased about 5 years ago and it’s had a strange sound from the exhaust since day 1. Literally sounds like a plastic bag is flapping around inside the exhaust, that’s the best way I can describe it. I’ve researched and researched and researched and googled my ass off for days now with no good leads on a possible cause. Anybody out there ever have this issue or know someone that has? In all my years I’ve never heard a Cummins sound like this so I have no idea....sounds like shit, makes me not even want to drive it. Someone out there please help. I tried uploading a video but the site won’t let me for some reason.

No one out there with a similar issue or idea on a possible problem and solution? Dying to be rid of a sound that’s just down right embarrassing, especially for a Cummins. I’d like to add that the sound I speak is the same directly out of the turbo with the down pipe pulled. I only mention this because I was certain it sounded the way it did at first due particular bends and such throughout the exhaust system that was causing the issue but it’s absolutely not.

Thanks for finally chiming in Jbear. Man, If every 12 valve sounds like this then I’m no longer a 12 valve fan, this thing sounds like shit. Has an upgraded HE351 but the exhaust has sounded this way since the hx35. No shaft play and no oil in the exhaust. Just recently added injectors, delivery valves and afc live and the truck runs great but still sounds like crap. I haven’t found a YouTube clip yet of a 12 valve that sounds like mine. If I could figure out how to load a sound clip of mine I would but something tells me you won’t pick up on it in a video.

No, it’s 100% coming from the engine out the tail pipe. Pulled the exhaust and you can directly hear it coming out the turbo. I really wish I could post a video, it might really help explain.

Still no one out there that has any thoughts on this issue? Every time I hear a 12 valve and the fact mine sounds nothing like it I get pissed. Someone out there has had to have had some sort of encounter with what I’m dealing with, I can’t be the only one can I?

4” turbo back to a muffler and then out to 6” stacks. But like I stated earlier, I have pulled the exhaust completely off at the turbo and it sounds exactly the same, louder obviously but the same phhh phh phh phh flutter. Many 12 valves I hear even have that cool turbo noise out the end of the pipe when you decel and shift gears and I don’t get that in the slightest. I don’t know why my truck sounds so different but I am beyond desperate to figure something out here.