Tracking down grinding engine noise. Please help!!

N55benji · 08-26-2020, 04:49 PM

This noise has been driving me crazy because both my mechanics and I cannot figure out what this noise is. Does anyone have any idea what it may be? It is much more noticeable when in cold weather when mildly accelerating (maybe around 3k rpms). Only noticeable when driving and you will not hear it when in park, neutral, or reverse. Please! Any ideas will help!!

thejeremyman9 · 08-26-2020, 04:55 PM

You need to provide more info. Does it happen the same in P/D/N? Or only when driving? RPM dependent or speed dependent? Any change depending on braking or accelerating versus coasting?

Read my post here and see if it might be the same thing, although it seems different. https://f30.bimmerpost.com/forums/sh....php?t=1708574

N55benji · 08-26-2020, 05:01 PM

Sorry you're right, I forgot to add more info that would be helpful. It is much more noticeable when in cold weather and when mildly accelerating (maybe around 3k rpms). Only noticeable when driving and you will not hear it when in park, neutral, reverse, or when breaking. I also notice it more at lower speeds when I mildly accelerate.

thejeremyman9 · 08-26-2020, 05:23 PM

Quote:

Originally Posted by N55benji

Sorry you're right, I forgot to add more info that would be helpful. It is much more noticeable when in cold weather and when mildly accelerating (maybe around 3k rpms). Only noticeable when driving and you will not hear it when in park, neutral, reverse, or when breaking. I also notice it more at lower speeds when I mildly accelerate.

Does the actual operating temperature of the engine/oil/transmission have any affect?

cfm56d7b · 08-26-2020, 05:30 PM

Does your vehicle have any mods?

N55benji · 08-26-2020, 05:31 PM

Quote:

Originally Posted by cfm56d7b

Does your vehicle have any mods?

Nope, my car is stock

N55benji · 08-26-2020, 05:33 PM

Quote:

Originally Posted by thejeremyman9

Does the actual operating temperature of the engine/oil/transmission have any affect?

Not that I know of. My guess is that it might be a plastic piece that’s loose somewhere and it’s vibrating, but it’s weird how it’s more noticeable in cold weather

cfm56d7b · 08-26-2020, 05:54 PM

Quote:

Originally Posted by N55benji

Nope, my car is stock

Thanks for confirming. It's perhaps too obvious: up close inspection of all hoses, connectors, clamps in the engine bay would be a prudent step.

If the noise is consistently heard, the root cause will eventually found.

Eschmacher · 08-26-2020, 10:41 PM

Mine does this too, especially when the AC is on. I've just learned to live with it.

thejeremyman9 · 08-27-2020, 12:02 AM

Quote:

Originally Posted by Eschmacher

Mine does this too, especially when the AC is on. I've just learned to live with it.

It's not realted to the TSB about the rattle is it?

XutvJet · 08-27-2020, 01:24 PM

Most likely something is loose in the area of the transmission tunnel or engine/transmission/exhaust mount is broken. The fact that it only does it under load makes me think it's a broken or failing mount. You'll need to get under the car to inspect.

Eschmacher · 08-27-2020, 09:28 PM

Quote:

Originally Posted by thejeremyman9

It's not realted to the TSB about the rattle is it?

The one where they add the weight to that hose? It could be, mine is missing that weight.

thejeremyman9 · 08-27-2020, 10:45 PM

Quote:

Originally Posted by Eschmacher

The one where they add the weight to that hose? It could be, mine is missing that weight.

Yeah, that one. Worth checking out.

08-26-2020, 04:49 PM	#1
N55benji Registered 0 Rep 4 Posts Drives: Bmw 335i Join Date: Aug 2020 Location: Texas iTrader: (0)	Tracking down grinding engine noise. Please help!! This noise has been driving me crazy because both my mechanics and I cannot figure out what this noise is. Does anyone have any idea what it may be? It is much more noticeable when in cold weather when mildly accelerating (maybe around 3k rpms). Only noticeable when driving and you will not hear it when in park, neutral, or reverse. Please! Any ideas will help!! Last edited by N55benji; 08-26-2020 at 04:58 PM..
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08-26-2020, 04:55 PM	#2
thejeremyman9 Major General 4364 Rep 7,606 Posts Drives: 2015 BMW 335i Join Date: May 2019 Location: Cali iTrader: (0)	You need to provide more info. Does it happen the same in P/D/N? Or only when driving? RPM dependent or speed dependent? Any change depending on braking or accelerating versus coasting? Read my post here and see if it might be the same thing, although it seems different. https://f30.bimmerpost.com/forums/sh....php?t=1708574
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08-26-2020, 05:01 PM	#3
N55benji Registered 0 Rep 4 Posts Drives: Bmw 335i Join Date: Aug 2020 Location: Texas iTrader: (0)	Sorry you're right, I forgot to add more info that would be helpful. It is much more noticeable when in cold weather and when mildly accelerating (maybe around 3k rpms). Only noticeable when driving and you will not hear it when in park, neutral, reverse, or when breaking. I also notice it more at lower speeds when I mildly accelerate.
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08-26-2020, 05:30 PM	#5
cfm56d7b Lieutenant General 5886 Rep 10,256 Posts Drives: 2017 440i Gran Coupe & 2015 X5 Join Date: Nov 2012 Location: Orange County, CA iTrader: (2)	Does your vehicle have any mods?
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08-26-2020, 10:41 PM	#9
Eschmacher Car Hypochondriac 335 Rep 901 Posts Drives: 2014 335i M-Sport Estoril Blue Join Date: Feb 2017 Location: Sterling, VA iTrader: (0) Garage List 2014 BMW 335i [0.00]	Mine does this too, especially when the AC is on. I've just learned to live with it. __________________ Power mods: VRSF IC/Catted DP - FTP CP/BP - AFE Cat-back - BM3/XHP - Dorch S2 Handling mods: Koni yellow - Eibach prokit - Millway street - M Performance LSD - M3 brakes - EBC bluestuff Exterior: Euro LCI tail lights - Shitty ECS CF spoiler - Chinese M performance diffuser Interior: Bavsound stage 1 and subs - custom trunk sub by Mike1327
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08-27-2020, 01:24 PM	#11
XutvJet Major General 5554 Rep 5,372 Posts Drives: 2011 Cayman Base, 2016 M235 Join Date: Mar 2016 Location: Kansas City iTrader: (-1)	Most likely something is loose in the area of the transmission tunnel or engine/transmission/exhaust mount is broken. The fact that it only does it under load makes me think it's a broken or failing mount. You'll need to get under the car to inspect. __________________ The forest was shrinking, but the Trees kept voting for the Axe, for the Axe was clever and convinced the Trees that because his handle was made of wood, he was one of them.
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