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Q: car won't start

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I've got a mercedes c300 2011 that won't start. I believe the battery is okay because when I turn the ignition all electrical components respond quickly as they should. When I turn the ignition I do hear what sounds like the starter motor spinning without engaging the flywheel. I have verified fuses that I believe are associated with the starter system and they also appear okay. Is this more than likely a bad solenoid?

My car has 50000 miles.
My car has an automatic transmission.

A: When the solenoid is energized, the pinion ...

When the solenoid is energized, the pinion gear is forced out by a plunger or lever to mesh with the ring gear. If the starter motor is spinning, freely, without the pinion gear engaging the flywheel, then something is wrong with the pinion gear assembly (lever, etc.) within the solenoid. Prior to condemning the starter though (best to replace starter/solenoid as one assembly) be sure that the solenoid is indeed getting 12.6 volt power, with NO voltage drop, when you turn the key to the start position. If your Mercedes Benz dealer sells rebuilt starters, that is the recommended source for this starter unless you have identified a reputable supplier in the aftermarket. Should you desire that a certified professional from YourMechanic diagnose this no start issue, and if necessary procure and replace the starter, by all means please schedule a mobile visit to get this taken care of.

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