# Mercedes 300SE-1991

**URL:** <https://community.cartalk.com/t/mercedes-300se-1991/10358>\
**Category:** Maintenance/Repairs\
**Created:** [February 8, 2008, 4:04pm UTC](https://community.cartalk.com/t/mercedes-300se-1991/10358 "2008-02-08T16:04:22Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mrdan89](https://avatars.discourse-cdn.com/v4/letter/m/e274bd/32.png) [@mrdan89](https://community.cartalk.com/u/mrdan89)\
**Post date:** [February 8, 2008, 4:04pm UTC](https://community.cartalk.com/t/mercedes-300se-1991/10358/1 "2008-02-08T16:04:22Z")

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The air injection pump has gone bad three times in a 2 years. I have used rebuilt. And what does the smog pump clutch magnet do?

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**Author:** ![Baxter\_s\_Dad](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/baxter_s_dad/32/27_2.png) [@Baxter\_s\_Dad](https://community.cartalk.com/u/Baxter_s_Dad)\
**Post date:** [February 9, 2008, 5:14am UTC](https://community.cartalk.com/t/mercedes-300se-1991/10358/2 "2008-02-09T05:14:28Z")

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I engages and disengages the air pump using electrical impulse signals from the computer.

Failure on these pumps is almost always the bearings. Is the belt tension at spec?

Benzman

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**Author:** ![mrdan89](https://avatars.discourse-cdn.com/v4/letter/m/e274bd/32.png) [@mrdan89](https://community.cartalk.com/u/mrdan89)\
**Post date:** [February 11, 2008, 12:12pm UTC](https://community.cartalk.com/t/mercedes-300se-1991/10358/3 "2008-02-11T12:12:39Z")

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Thanks, Benzman,  
I will check to see if the mechanic checked the belt tension.