Flowmaster Am Thunder NPP valve rattle?

MAGAUSA · 06-08-2018, 10:55 AM

I’ve seen some reports of this. How prevalent is this and anyone know if it’s a warranty item?

My stock NPP rattles so much on one side I never use anything but track mode. Driving in Tour and esp Stealth brings this loud tinny rattle from the one side. But I’m looking for a functioning aftermarket and I’d need the valves for start ups and cruising in the neighborhood. More rattles would be disappointing.

Anyone with experience with this system?

Thanks

Camaro 79 · 06-18-2019, 12:35 PM

So I just got mine installed and it has a SIGNIFICANT rattle. It wasn't there the first couple of days, but yesterday morning I started up and went to stealth, and it was loud and prevalent.

For what it's worth, I had no issues with the Stock NPP, but I felt the sound was underwhelming so I never used it anyway. Now that I want the functionality... I don't seem to have it.

Baker · 06-23-2019, 11:00 PM

https://www.camaro6.com/forums/showthread.php?t=556657 check this out worked for me

Camaro 79 · 06-24-2019, 08:14 AM

Check the thread that Baker posted, the ziptie under the spring that is problematic (after you compress it) completely solved the problem.

KingLT1 · 06-24-2019, 09:31 AM

That is odd...the spring tension is really tight on my Flowmaster valves. Actually both exhausts were. Flowmaster sent me a replacement because the valves leak when closed creating a "hissing" sound. I thought the springs were too stiff not allowing the NPP actuator to close them. Sounds like perhaps Flowmaster reduced tension on the springs so the NPP actuators don't have to work as hard to close the valves, but then the springs rattle.

Camaro 79 · 06-24-2019, 10:19 AM

Quote:

Originally Posted by KingLT1

That is odd...the spring tension is really tight on my Flowmaster valves. Actually both exhausts were. Flowmaster sent me a replacement because the valves leak when closed creating a "hissing" sound. I thought the springs were too stiff not allowing the NPP actuator to close them. Sounds like perhaps Flowmaster reduced tension on the springs so the NPP actuators don't have to work as hard to close the valves, but then the springs rattle.

Interesting, I didn't have a "hissing" problem, but I had a SIGNIFICANT rattle. The zip tie completely solved that for me, and I'm thrilled with the exhaust now.

SmurfMaf1a · 01-06-2020, 02:13 PM

Hi, Do you have any pics of where you ziptied underneath? Do you just ziptie anywhere underneath?

06-08-2018, 10:55 AM	#1
MAGAUSA Drives: 2017 Hyper Blue 1LE Join Date: Dec 2016 Location: Tampa Posts: 579	Flowmaster Am Thunder NPP valve rattle? I’ve seen some reports of this. How prevalent is this and anyone know if it’s a warranty item? My stock NPP rattles so much on one side I never use anything but track mode. Driving in Tour and esp Stealth brings this loud tinny rattle from the one side. But I’m looking for a functioning aftermarket and I’d need the valves for start ups and cruising in the neighborhood. More rattles would be disappointing. Anyone with experience with this system? Thanks

06-18-2019, 12:35 PM	#2
Camaro 79 Drives: 2018 Camaro SS Join Date: Feb 2016 Location: DMV Posts: 129	So I just got mine installed and it has a SIGNIFICANT rattle. It wasn't there the first couple of days, but yesterday morning I started up and went to stealth, and it was loud and prevalent. For what it's worth, I had no issues with the Stock NPP, but I felt the sound was underwhelming so I never used it anyway. Now that I want the functionality... I don't seem to have it. __________________ Current - 2018 Camaro 1SS with MRC, 1LE Suspension, NPP Exaust, 6 Speed. Past - 2016 Ford Mustang GT Performance Pack 2015 Camaro SS 2010 Ford Mustang GT

06-23-2019, 11:00 PM	#3
Baker Drives: 2010 camaro RS,2017 camaro 1Le Join Date: Mar 2016 Location: Charlotte, NC Posts: 195	https://www.camaro6.com/forums/showthread.php?t=556657 check this out worked for me __________________ 2017 camaro 1le ROTO fab, Ported MSD, Ported 95mm tb, 2in TSP catless longtubes, flowmaster x-pipe, flowmaster American thunder npp, flex fuel,

06-24-2019, 08:14 AM	#4
Camaro 79 Drives: 2018 Camaro SS Join Date: Feb 2016 Location: DMV Posts: 129	Check the thread that Baker posted, the ziptie under the spring that is problematic (after you compress it) completely solved the problem. __________________ Current - 2018 Camaro 1SS with MRC, 1LE Suspension, NPP Exaust, 6 Speed. Past - 2016 Ford Mustang GT Performance Pack 2015 Camaro SS 2010 Ford Mustang GT

06-24-2019, 09:31 AM	#5
KingLT1 Drives: 2016 1SS NFG A8 Join Date: Aug 2017 Location: 46804 Posts: 6,801	That is odd...the spring tension is really tight on my Flowmaster valves. Actually both exhausts were. Flowmaster sent me a replacement because the valves leak when closed creating a "hissing" sound. I thought the springs were too stiff not allowing the NPP actuator to close them. Sounds like perhaps Flowmaster reduced tension on the springs so the NPP actuators don't have to work as hard to close the valves, but then the springs rattle. __________________ 2016 NFG 1SS A8 Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA

01-06-2020, 02:13 PM	#7
SmurfMaf1a Drives: 2016 Camaro 1SS M6 Join Date: Jun 2016 Location: Tampa,Fl Posts: 34	Hi, Do you have any pics of where you ziptied underneath? Do you just ziptie anywhere underneath?

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