2008 Sebring 2.4l 67000 miles I'm getting knocking and whirring from engine.

On a hunch I replaced the alternator and the noise is gone. Guess you shouldn't trust what the parts store tells you. I think their machine made so much noise it covered the sound. Thanks for your response.

Glad you got it fixed!

On a hunch I replaced the alternator and the noise is gone. Guess you shouldn't trust what the parts store tells you. I think their machine made so much noise it covered the sound. Thanks for your response.

Your hunch was partially correct. The alternator may test as good on the parts store machine because their machine does not put the same amount of tension on the decoupler pulley as there is when it is installed in your car. the alternator itself is/was probably fine. The noise was most likely caused by a bad bearing in the decoupler pulley. They are known to fail and yet so few people, even seasoned mechanics, know of the problem. These decoupler pulleys are replaceable. You can usually find them online for around $45-50, which is a huge difference from the $240-280 you would spend on a new alternator. Maybe the mechanics DO know about this and are charging for a new alternator, but only replacing the pulley for a better profit margin.

Sorry you feel that way! However not everyone is a crook!!! No indication here that alternator replacement was suggested as a repair! You can replace the decoupler,,,,'IF' that is the problem!!!