Im trying to figure out if this is normal header noise or if something has gone out of whack. Before I ever messed with the exhaust (all stock) this motor was quiet as can be. All of my exhaust bolts are tight as can be, I've triple checked. It's like a light knocking noise that's in rhythm with the engine...but it's loud...it can easily be heard over the cutout and is loudest on the passenger side.

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Sounds a whole lot like mine at idle.

 

His truck must sound a whole lot like mine does.

 

Does it sound like a lifter? Did you use the stock manifold gaskets or the paper header gaskets?
I'd check the gaskets. Blew one out on the driver side once and you'd swear I bent a pushrod

 

They are the original stock MLS gaskets. The ones on the drivers side did come apart ( the three pieces came apart) but I don't see how that would affect anything. I don't see how these metal gaskets could go bad either. I sprayed soap water all over the flange area and there was no leaks

 

I would look into the gasket's as well. However it's hard to tell from a video, it could be a bad lifter...

 

heres how mine sound



dont mind that **** on my passenger side header, its stop leak **** from when i tied to fix my heater core haha

 

would be nice if you could get some video down by the wheel wells.....mine sounds fine up in the bay....just by the sides, or underneath is sounds like knock or something

 

My springs make noises like I've got an exhaust leak at the collectors down at the bottom but i know they aren't leaking. I'm thinking about taking the headers off and using new header gaskets and switching over to 10-30 oil. But, when I get the money I'm gonna get some worked over heads and swap to ls7 lifters and better springs, so hopefully my valvetrain wont be so damn noisy.

 

What mods do you have GMC? aftermarket springs are usually loud, and since LT's are so thin the noise from the valvetrain resonates through the headers easier.