# 2005 Mercedes-Benz C-Class - Whines

**URL:** <https://community.cartalk.com/t/2005-mercedes-benz-c-class-whines/170568>\
**Category:** Maintenance/Repairs\
**Tags:** mercedes-benz\
**Created:** [September 28, 2020, 6:46pm UTC](https://community.cartalk.com/t/2005-mercedes-benz-c-class-whines/170568 "2020-09-28T18:46:49Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Sam48](https://avatars.discourse-cdn.com/v4/letter/s/ac8455/32.png) [@Sam48](https://community.cartalk.com/u/Sam48)\
**Post date:** [September 28, 2020, 6:46pm UTC](https://community.cartalk.com/t/2005-mercedes-benz-c-class-whines/170568/1 "2020-09-28T18:46:49Z")

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My 2005 Mercedes C240 4matic wagon (126,000 mi) has had an engine whine for as long as I can remember. Any thoughts?

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**Author:** ![davepsinbox\_157004](https://avatars.discourse-cdn.com/v4/letter/d/73ab20/32.png) [@davepsinbox\_157004](https://community.cartalk.com/u/davepsinbox_157004)\
**Post date:** [September 28, 2020, 10:42pm UTC](https://community.cartalk.com/t/2005-mercedes-benz-c-class-whines/170568/2 "2020-09-28T22:42:22Z")

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Your _engine_ is unlikely to be making the noise. The usual suspects are power steering, transmission, and differential. If you have awd I’d start with the rear differential but a good mechanic with a stethoscope can pinpoint the noise if you really want to know.

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**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\
**Post date:** [September 28, 2020, 11:42pm UTC](https://community.cartalk.com/t/2005-mercedes-benz-c-class-whines/170568/3 "2020-09-28T23:42:31Z")

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You sure it’s the engine?

If so, it could be an idler pulley

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**Author:** ![shadowfax](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/shadowfax/32/13026_2.png) [@shadowfax](https://community.cartalk.com/u/shadowfax)\
**Post date:** [September 29, 2020, 12:10am UTC](https://community.cartalk.com/t/2005-mercedes-benz-c-class-whines/170568/4 "2020-09-29T00:10:31Z")

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The others have good suggestions. Also, if you turn the radio off, does it still do it?

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**Author:** ![SteveCBT](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/stevecbt/32/3192_2.png) [@SteveCBT](https://community.cartalk.com/u/SteveCBT)\
**Post date:** [September 29, 2020, 12:15am UTC](https://community.cartalk.com/t/2005-mercedes-benz-c-class-whines/170568/5 "2020-09-29T00:15:49Z")

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Is the noise engine speed related or vehicle speed related? Take the car out on a road when it is not crowded and downshift to see if the noise changes pitch. If you can do it safely try putting it in neutral when moving to see if it changes.

Does it do it when the car is not moving?

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [September 29, 2020, 12:17am UTC](https://community.cartalk.com/t/2005-mercedes-benz-c-class-whines/170568/6 "2020-09-29T00:17:47Z")

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The secondary air pump can make a whining noise.

 ![image](https://global.discourse-cdn.com/cartalk/original/3X/8/8/88659463ef5870d1ab0b1a6460f90fca70c1f9cf.jpeg)

Tester