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Showing results for tags 'flapper valve'.
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I have a 2017 GMC Siearra 1500 with the 5.3L & 8 speed transmission. There is a rattle noise that you can hear at cold start. I have seen posts on this issue and answers seem to be all over the place. When my truck sits overnight or while at work all day, there is a rattle that sounds to me like it is coming from the exhaust. I haven't gotten under the truck to see exactly where the sound is coming from. It typically lasts about 5-10 seconds. If you immediately put the truck in gear after startup the rattle goes away. Any info on exactly what this may be is appreciated. I have seen suggestions of torque converter, heat shield, hole in exhaust, flapper valve, and bad catalytic converter. Can anybody narrow this down to one of these issues?
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I've read enough about these valves to want to clamp it in the full open position until I can delete it entirely when I get a cat-back exhaust. But, how in the hell do you clamp off the round ones on the 2018 trucks? Here's what mine looks like, and a simple hose clamp managed to slip off after only two days.
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- exhaust
- flapper valve
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I've got a 2014 5.3L Silverado and yes it has the AFM I want it gone but for now I have to deal with it. I had a flowmaster 40 series installed and resonator cut off, and it is very quiet. I see no flapper valve so I am assuming that he cut it off to (which I was unaware of a flapper valve at the time). My question is, why is it so quiet? Does the AFM make that big of a difference In sound even when in v8? Is the flapper valve still there? Did the guy do something to make the truck quieter (we had a small disagreement while he was installing the system, and after he was done he said "if you ever want it louder we can cut off the 3rd cat"). Any help is greatly appreciated and I am going to try and put pics in the comments cuz it will not let me in the the post.