Rattling under throttle

passthetongs · 08-08-2020, 05:11 PM

Hi everyone, my 211 e70 35i started developing a weird rattling sound. It almost sounds like a rock bouncing around in a metal cage. It occurs under throttle, at park as well as driving. No sound during idle, but it does occur when I apply the throttle and seems to get more aggressive the more gas I give it. Could it be a tensioner? It sounds like it’s coming from the front to mid driver side. I’ve replaced a tensioner a year or two ago but it sounds nothing like a tensioner going out... more metallic and tinny almost like a stick is wrapped around the drive shaft and hitting a exhaust shield? But it happens when I step on the gas in park as well.

Lviv777 · 08-10-2020, 10:55 AM

Could it be a misfire? I had something similar, and it turned out to be a misfire because of a bad coil.

drummr8 · 08-12-2020, 01:16 PM

That sounds like the description of VANOS rattle that I remember from my M54 days (marbles in a can). As far as I know the design is different on our N55 so doesn't have the same issue... post a video if you can pick the sound up on there.

passthetongs · 08-18-2020, 03:43 PM

SOLVED! definitely not the way I wanted solve this mystery, but it turns out it was the serpentine belt. It must have started to shred and slap around until it eventually slipped off while I was on the interstate. I was able to wrangle it home and throw on a spare belt I had in storage. Thanks again for the suggestions!

08-08-2020, 05:11 PM	#1
passthetongs New Member 1 Rep 10 Posts Drives: E70 X5 Xdrive35i Join Date: Feb 2019 Location: USA iTrader: (0)	Rattling under throttle Hi everyone, my 211 e70 35i started developing a weird rattling sound. It almost sounds like a rock bouncing around in a metal cage. It occurs under throttle, at park as well as driving. No sound during idle, but it does occur when I apply the throttle and seems to get more aggressive the more gas I give it. Could it be a tensioner? It sounds like it’s coming from the front to mid driver side. I’ve replaced a tensioner a year or two ago but it sounds nothing like a tensioner going out... more metallic and tinny almost like a stick is wrapped around the drive shaft and hitting a exhaust shield? But it happens when I step on the gas in park as well. Last edited by passthetongs; 08-08-2020 at 05:21 PM..
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08-10-2020, 10:55 AM	#2
Lviv777 Second Lieutenant 42 Rep 269 Posts Drives: f30 330e, C8 Vette Join Date: Oct 2017 Location: Highway iTrader: (0)	Could it be a misfire? I had something similar, and it turned out to be a misfire because of a bad coil.
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08-12-2020, 01:16 PM	#3
drummr8 6MT FTMFW 61 Rep 229 Posts Drives: 11 E90 335xi E91 6MT 12 X5 35i Join Date: Feb 2019 Location: SC iTrader: (0) Garage List 2005 330ci Vert ZHP [0.00] 2011 335xi Sedan M- ... [0.00] 2011 328xi Wagon M- ... [0.00] 2012 X5 35i M-Sport [0.00]	That sounds like the description of VANOS rattle that I remember from my M54 days (marbles in a can). As far as I know the design is different on our N55 so doesn't have the same issue... post a video if you can pick the sound up on there. __________________ 2011 LMB E90 335xi 6MT: Wagner EvoII FMIC, Catless DP, PE Mod, Cobb CP, BMC Filter, ST Coilovers, Strongflex TSB's, Whiteline RSFB Inserts, CDV Delete, Hawk Talon Rotors & PC Pads 2011 SGM E91 328xi 6MT: 3-Stage Intake Manifold, ST coilovers, 335i brake kit, drilled/slotted rotors, CDV Delete, Charcoal Filter Delete
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08-18-2020, 03:43 PM	#4
passthetongs New Member 1 Rep 10 Posts Drives: E70 X5 Xdrive35i Join Date: Feb 2019 Location: USA iTrader: (0)	SOLVED! definitely not the way I wanted solve this mystery, but it turns out it was the serpentine belt. It must have started to shred and slap around until it eventually slipped off while I was on the interstate. I was able to wrangle it home and throw on a spare belt I had in storage. Thanks again for the suggestions!
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