High pitch sound at cold start
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Newbie
Joined: Aug 2018
Posts: 11
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W212
High pitch sound at cold start
My car makes a high pitch noise in the first 30-40 sec of the start up. After that it sounds and drives just fine. Not long ago I changed the serpentine belt. Any idea what might be the problem? I also don’t see any fluid leaking. The car is 2010 w212 model with 120,000 km.
thank you.
thank you.
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
AIR PUMP
Holly cow... it's hard to ignore that 
I think you can focus on testing your electric AIR INJECTION PUMP more so than serpentine or steering pump.
You can use your handy scanner to control its power ON/OFF.
Unplug connector if you time until your parts arrive.
I think you can focus on testing your electric AIR INJECTION PUMP more so than serpentine or steering pump.
You can use your handy scanner to control its power ON/OFF.
Unplug connector if you time until your parts arrive.
Last edited by CaliBenzDriver; Jan 1, 2025 at 06:18 PM.
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,769
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
scanner control
You can use your handy scanner to control pump power ON/OFF.
(Unplugging may bring up a code)
MBWorld Fanatic!
Joined: Aug 2023
Posts: 3,687
Likes: 1,107
From: MA Coast
W204 2010 C300 4matic Sport M272
Sounds like someons is cutting wood with a circular saw.
Im guessing your secondary air pump is shot. Disconnect it before the next cold start and see if it goes away.
Im guessing your secondary air pump is shot. Disconnect it before the next cold start and see if it goes away.
MBWorld Fanatic!
Joined: May 2018
Posts: 6,600
Likes: 6,543
From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
You wont get error code from a bad bearing of secondary air injection pump of M272 / M273
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19 GLA45, 86 560SL, former: 14 E550 4Matic, 09 E350 4Matic, 83 240D manual, 78 450SLC, 81 500SLC
You wont get error code from a bad bearing of secondary air injection pump of M272 / M273
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