Exhaust rattle causes and technical info

Alex09_335 · 05-14-2015, 01:32 PM

Hello,

I'm familiar with the golf tee mod. My exhaust has started to rattle from the butterfly valve. What I've noticed is when I touch the actual actuator or the pin at the bottom of the butterfly valve it seems to silence the rattle.

Is there a way to adjust the actuator so it can apply more force to seat the valve properly? Or any other method that can be done to silence the rattle without affecting the operation of the valve.

Could lubricating the mechanisim also help?

Also are there any actual BMW techs who know the exact operation condition for this flap. There seem to be many differing views floating around when I search for answers. Some say the flap is only in operation at start up, others say it operates under 2500rpm.

From my personal experience it seems to operate for approx 30sec then goes to the open position. Once open I can't detect any rattle while driving under 2500rpm but also cannot actually stand behind the vehicle to do a visual inspection of the flap position.

As far as preformance concerns there are also conflicting statments that either turbo charged engines do not require back pressure and the flap is purely for heating up the cat and noise mitigation or it is required for optimal low end torque.

What is the actual cause of these rattles? Is it a worn or out of adjustment actuator, worn flap/pin, carbon build up, low vacume pressure/leak or malfunctioning trunk solenoid.

Any technical information would be appreciated (other then golf tee/solenoid disconnection)

Thanks, Alex

Bavarian Tech · 05-14-2015, 03:00 PM

The true fix is to replace the muffler, theirs no repair kits once it starts to rattle..I sure you could take a pry bray and a hammer and break it/remove it. But thats your call

Alex09_335 · 05-15-2015, 04:01 PM

I've managed to temporarily silence the rattle with an elastic band tied to the actuator arm. Seems to still open and close during warm up. Hopefully it doesn't melt on a long drive

Any idea why these flaps start to rattle? My car has 35000km seems a little premature to be dealing with stuff like this.

05-14-2015, 01:32 PM	#1
Alex09_335 Private First Class 31 Rep 122 Posts Drives: 2009 BMW 335i Join Date: Dec 2014 Location: Toronto iTrader: (0)	Exhaust rattle causes and technical info Hello, I'm familiar with the golf tee mod. My exhaust has started to rattle from the butterfly valve. What I've noticed is when I touch the actual actuator or the pin at the bottom of the butterfly valve it seems to silence the rattle. Is there a way to adjust the actuator so it can apply more force to seat the valve properly? Or any other method that can be done to silence the rattle without affecting the operation of the valve. Could lubricating the mechanisim also help? Also are there any actual BMW techs who know the exact operation condition for this flap. There seem to be many differing views floating around when I search for answers. Some say the flap is only in operation at start up, others say it operates under 2500rpm. From my personal experience it seems to operate for approx 30sec then goes to the open position. Once open I can't detect any rattle while driving under 2500rpm but also cannot actually stand behind the vehicle to do a visual inspection of the flap position. As far as preformance concerns there are also conflicting statments that either turbo charged engines do not require back pressure and the flap is purely for heating up the cat and noise mitigation or it is required for optimal low end torque. What is the actual cause of these rattles? Is it a worn or out of adjustment actuator, worn flap/pin, carbon build up, low vacume pressure/leak or malfunctioning trunk solenoid. Any technical information would be appreciated (other then golf tee/solenoid disconnection) Thanks, Alex Attached Images
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05-14-2015, 03:00 PM	#2
Bavarian Tech Major 267 Rep 1,203 Posts Drives: 335i Join Date: Jan 2007 Location: Pittsburgh/Harrisburg iTrader: (15) Garage List 2006 330i [10.00]	The true fix is to replace the muffler, theirs no repair kits once it starts to rattle..I sure you could take a pry bray and a hammer and break it/remove it. But thats your call
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05-15-2015, 04:01 PM	#3
Alex09_335 Private First Class 31 Rep 122 Posts Drives: 2009 BMW 335i Join Date: Dec 2014 Location: Toronto iTrader: (0)	I've managed to temporarily silence the rattle with an elastic band tied to the actuator arm. Seems to still open and close during warm up. Hopefully it doesn't melt on a long drive Any idea why these flaps start to rattle? My car has 35000km seems a little premature to be dealing with stuff like this.
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