Weird rear end sound

Mirko · 03-07-2012, 12:42 PM

My car was completely quiet in the rear, was out in a bad snow storm and didn't hit anything or go into any ditches. Drove to a friends house, car was parked and as I left was driving down the street a few blocks away and a weird clunk sound from the driverside rear. I thought at first it might be snow build up and ice so washed the car and the sound seemed to occur less frequently. However sometimes it will return driving slower speeds usually on a crappy road or bumps in the road. Checked the RSM a few days later once the weather warmed up. They look okay.

This past weekend got under the car and pulled on the suspension components and nothing would replicate it the sound. Bushings don't look damaged or worn and nothing seems loose. Checked sway bar links as well.

A more recent sound has become apparent. Driving around 60-100km/hr even on a smooth road it sounds like popcorn popping in my trunk. It's faint but you can hear it. Have tried with radio off, heat off, even in neutral and the sound is there.

I wonder if the RSM bushing is gone and as the car goes over the surface it goes up and down similar to what others have described as the metal and rubber clanking over each other.

Taking the car to BMW next week to get checked out as its still under warranty. Note that I did install the Stromung exhaust but this was a month or two before this noise came so don't think its an exhaust leak.

Coles notes: Rear end clunk over bumps at low speeds at times and at higher speed it sounds like popcorn popping while driving.
Anyone else run into a similar issue? Thanks

boondocksaint · 03-07-2012, 02:54 PM

Exhaust hangar/clearance?
Strut mount?
Wheel bearing? Not the usual noise associated with this, but they're weird sometimes.
Diff mount?

For some reason, I'd want to check the interior panels and make sure some of the plastic fasteners haven't backed out.

Etch52 · 03-07-2012, 04:17 PM

Had this happen while driving my Honda Pilot...
Turned out to be ice buildup above the crankcase area. The touch-less car wash didn't clean it out.
Same sounds .. quieter on acceleration.. guess the ice was moving around.
It doesn't take much to make a lot of noise inside.

MHeavNC · 03-08-2012, 06:29 AM

Had a popping sound coming from the rear end once.. Thought something was loose but found out that the trunk liner/cover was making the sound.. It wasn't pulled out at the time.. I opened the trunk and pulled it to cover the trunk back up, and no more popping sound.. It also hides my golf clubs... I hope your noise is as simple and nothing serious...

Mirko · 03-08-2012, 07:59 AM

thank you guys .. will take a look at the panels/liner on Saturday to see if it's all tight. Will also take the car to a power wash and try to get under the car. Also going to check passengerside rsm and under carriage.

I wonder if its wind related, it has been windy these past two days. Could be a gap somewhere in the molding.

Mirko · 03-13-2012, 11:29 AM

The weird popcorn sort of sound is due to the window rubbing on the rubber. BMW is currently replacing the window regulators on both the driver and passenger sides.

They are also checking my suspension, so will report back if they find anything there. I think maybe the coil spring broke at the bottom as per the norm for these cars but thats idle speculation.

Huz-Z · 03-13-2012, 04:08 PM

I get the same thing when I eat certain veggies.

Retrodog · 03-13-2012, 04:27 PM

Quote:

Originally Posted by Etch52

Had this happen while driving my Honda Pilot...
Turned out to be ice buildup above the crankcase area. The touch-less car wash didn't clean it out.
Same sounds .. quieter on acceleration.. guess the ice was moving around.
It doesn't take much to make a lot of noise inside.

Did you find and remove it, or just wait for the spring thaw?

Etch52 · 03-13-2012, 07:06 PM

Quote:

Originally Posted by Retrodog

Did you find and remove it, or just wait for the spring thaw?

Dropped by the dealer. They found the ice. Problem solved.
I have lost a tooth in a rear diff before.. (not the Honda). I was prepared for the worst.

gcochard · 03-13-2012, 07:19 PM

Quote:

Originally Posted by Etch52

Dropped by the dealer. They found the ice. Problem solved.
I have lost a tooth in a rear diff before.. (not the Honda). I was prepared for the worst.

The worst, courtesy of my e36 m3:

03-07-2012, 12:42 PM	#1
Mirko Major 182 Rep 1,031 Posts Drives: E86 Z4M, E90 328i, E84 X1 Join Date: Apr 2011 Location: Toronto iTrader: (2)	Weird rear end sound My car was completely quiet in the rear, was out in a bad snow storm and didn't hit anything or go into any ditches. Drove to a friends house, car was parked and as I left was driving down the street a few blocks away and a weird clunk sound from the driverside rear. I thought at first it might be snow build up and ice so washed the car and the sound seemed to occur less frequently. However sometimes it will return driving slower speeds usually on a crappy road or bumps in the road. Checked the RSM a few days later once the weather warmed up. They look okay. This past weekend got under the car and pulled on the suspension components and nothing would replicate it the sound. Bushings don't look damaged or worn and nothing seems loose. Checked sway bar links as well. A more recent sound has become apparent. Driving around 60-100km/hr even on a smooth road it sounds like popcorn popping in my trunk. It's faint but you can hear it. Have tried with radio off, heat off, even in neutral and the sound is there. I wonder if the RSM bushing is gone and as the car goes over the surface it goes up and down similar to what others have described as the metal and rubber clanking over each other. Taking the car to BMW next week to get checked out as its still under warranty. Note that I did install the Stromung exhaust but this was a month or two before this noise came so don't think its an exhaust leak. Coles notes: Rear end clunk over bumps at low speeds at times and at higher speed it sounds like popcorn popping while driving. Anyone else run into a similar issue? Thanks
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03-07-2012, 02:54 PM	#2
boondocksaint Penfold, shush! 4 Rep 132 Posts Drives: 07 Z4MC Join Date: Mar 2011 Location: Charlotte iTrader: (0)	Exhaust hangar/clearance? Strut mount? Wheel bearing? Not the usual noise associated with this, but they're weird sometimes. Diff mount? For some reason, I'd want to check the interior panels and make sure some of the plastic fasteners haven't backed out.
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03-07-2012, 04:17 PM	#3
Etch52 Most roads are too short and too straight 2 Rep 66 Posts Drives: 2007 M Coupe - Premium Package Join Date: Jun 2011 Location: Ottawa, ON iTrader: (0) Garage List 2022 Honda CR-V [0.00] 2019 Honda Pilot Bl ... [0.00] 2007 BMW M Coupe [9.00]	Had this happen while driving my Honda Pilot... Turned out to be ice buildup above the crankcase area. The touch-less car wash didn't clean it out. Same sounds .. quieter on acceleration.. guess the ice was moving around. It doesn't take much to make a lot of noise inside. __________________ 2010 Honda Pilot Touring, 2013 328i xDrive Luxury Edition, 2007 M Coupe
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03-08-2012, 06:29 AM	#4
MHeavNC Turd in the Punch Bowl 19 Rep 239 Posts Drives: 2007 Z4 3.0i /// 2008 M Coupe Join Date: Aug 2010 Location: North Carolina iTrader: (0)	Had a popping sound coming from the rear end once.. Thought something was loose but found out that the trunk liner/cover was making the sound.. It wasn't pulled out at the time.. I opened the trunk and pulled it to cover the trunk back up, and no more popping sound.. It also hides my golf clubs... I hope your noise is as simple and nothing serious...
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03-08-2012, 07:59 AM	#5
Mirko Major 182 Rep 1,031 Posts Drives: E86 Z4M, E90 328i, E84 X1 Join Date: Apr 2011 Location: Toronto iTrader: (2)	thank you guys .. will take a look at the panels/liner on Saturday to see if it's all tight. Will also take the car to a power wash and try to get under the car. Also going to check passengerside rsm and under carriage. I wonder if its wind related, it has been windy these past two days. Could be a gap somewhere in the molding.
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03-13-2012, 11:29 AM	#6
Mirko Major 182 Rep 1,031 Posts Drives: E86 Z4M, E90 328i, E84 X1 Join Date: Apr 2011 Location: Toronto iTrader: (2)	The weird popcorn sort of sound is due to the window rubbing on the rubber. BMW is currently replacing the window regulators on both the driver and passenger sides. They are also checking my suspension, so will report back if they find anything there. I think maybe the coil spring broke at the bottom as per the norm for these cars but thats idle speculation.
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03-13-2012, 04:08 PM	#7
Huz-Z Brigadier General 851 Rep 4,057 Posts Drives: Z4 3.0si, 328 XDrive, X5 35i Join Date: Aug 2009 Location: Canada iTrader: (0)	I get the same thing when I eat certain veggies. __________________ Huz-Z BMW Z4 3.0si Roadster. Montego Blue Metallic. Premium and Sport Package.
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