Low grumble at idle on start

dancing__narwhal · 02-22-2018, 11:04 AM

Last week I started noticing a low grumbling sound at idle after starting the engine. it's not the blower motor as I have the fan off. The noise seems to go away as the idle settles and is also not noticeable at higher revs.

It may just be coincidence, but I started noticing it right after doing an oil change. All I did was oil & filter and check the air filter (k&n drop in, looks clean).

Any idea what this would be? Any cause for concern?

dancing__narwhal · 02-22-2018, 11:09 AM

Actually just tested a bit more. It doesnt seem to go away as the idle settles. Also I still notice it if I rev the engine a bit in neutral. It's harder to hear and definitely doesn't build as revs increase, but it's there.

desertman123 · 02-22-2018, 11:39 AM

Can you look around the engine bay with the motor running and try and hear where it's coming from?

Phyrexia · 02-22-2018, 11:47 AM

Automatic or manual? With manual cars, it's normal to hear some noise coming from the clutch/trans when the clutch is engaged and the transmission is in neutral.

dancing__narwhal · 02-22-2018, 03:04 PM

Quote:

Originally Posted by Phyrexia

Automatic or manual? With manual cars, it's normal to hear some noise coming from the clutch/trans when the clutch is engaged and the transmission is in neutral.

It's a manual. Happens with clutch in or not, and in gear or in neutral. I never noticed it before is the weird thing.

dancing__narwhal · 02-22-2018, 03:05 PM

Quote:

Originally Posted by desertman123

Can you look around the engine bay with the motor running and try and hear where it's coming from?

Thanks I'll give this a try

dancing__narwhal · 02-23-2018, 10:24 AM

I noticed yesterday that it seems to happen most consistently when i first start the engine (even if it was already warm) and then seems to have gone away after some driving. Not sure if this is always the case but that's what I noticed.

desertman123 · 02-23-2018, 11:12 AM

I'd take the belt off and inspect the pulleys.

GoRomeo · 02-23-2018, 11:26 AM

Quote:

Originally Posted by desertman123

I'd take the belt off and inspect the pulleys.

this.

dancing__narwhal · 02-23-2018, 11:42 AM

Quote:

Originally Posted by desertman123

I'd take the belt off and inspect the pulleys.

What would I be looking for?

02-22-2018, 11:04 AM	#1
dancing__narwhal First Lieutenant 142 Rep 337 Posts Drives: 2024 m340ix Join Date: Nov 2016 Location: Santa Barbara, CA iTrader: (0)	Low grumble at idle on start Last week I started noticing a low grumbling sound at idle after starting the engine. it's not the blower motor as I have the fan off. The noise seems to go away as the idle settles and is also not noticeable at higher revs. It may just be coincidence, but I started noticing it right after doing an oil change. All I did was oil & filter and check the air filter (k&n drop in, looks clean). Any idea what this would be? Any cause for concern?
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02-22-2018, 11:09 AM	#2
dancing__narwhal First Lieutenant 142 Rep 337 Posts Drives: 2024 m340ix Join Date: Nov 2016 Location: Santa Barbara, CA iTrader: (0)	Actually just tested a bit more. It doesnt seem to go away as the idle settles. Also I still notice it if I rev the engine a bit in neutral. It's harder to hear and definitely doesn't build as revs increase, but it's there.
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02-22-2018, 11:39 AM	#3
desertman123 E82 Mudflap Ambassador 2214 Rep 2,219 Posts Drives: '08 128i Join Date: May 2016 Location: Orlando, FL iTrader: (0) Garage List 1992 Honda Beat [9.50] 2008 BMW 128i [10.00] 2014 BMW 528i [10.00]	Can you look around the engine bay with the motor running and try and hear where it's coming from? __________________ My 2008 128i - Sparkling Graphite/Beige - Sport pkg - 6MT - Click me! Parents' 2014 528i - Mineral White/Ivory White - fully loaded Instagram @Andreys_128i and @Honda.Bito
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02-22-2018, 11:47 AM	#4
Phyrexia Resident Pedant 503 Rep 792 Posts Drives: '15 335i 8AT Join Date: Nov 2017 Location: Limbo iTrader: (1)	Automatic or manual? With manual cars, it's normal to hear some noise coming from the clutch/trans when the clutch is engaged and the transmission is in neutral. __________________ '15 F30 335i 8AT Estoril II/Black (12.218 @ 114.94mph) MHD Stage 2+ 93 / XHP Stage 3 / M-Goodies / K&N Filter / ER CP / CSF IC / NGK 97506 / ER DP / Michelin A/S 3+
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02-23-2018, 10:24 AM	#7
dancing__narwhal First Lieutenant 142 Rep 337 Posts Drives: 2024 m340ix Join Date: Nov 2016 Location: Santa Barbara, CA iTrader: (0)	I noticed yesterday that it seems to happen most consistently when i first start the engine (even if it was already warm) and then seems to have gone away after some driving. Not sure if this is always the case but that's what I noticed.
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02-23-2018, 11:12 AM	#8
desertman123 E82 Mudflap Ambassador 2214 Rep 2,219 Posts Drives: '08 128i Join Date: May 2016 Location: Orlando, FL iTrader: (0) Garage List 1992 Honda Beat [9.50] 2008 BMW 128i [10.00] 2014 BMW 528i [10.00]	I'd take the belt off and inspect the pulleys. __________________ My 2008 128i - Sparkling Graphite/Beige - Sport pkg - 6MT - Click me! Parents' 2014 528i - Mineral White/Ivory White - fully loaded Instagram @Andreys_128i and @Honda.Bito
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