BoatHowTo · video

What this video covers

Intermittent starter failure on a Yanmar diesel engine often results from pitted contact points inside the starter solenoid rather than electrical load issues from a high-output alternator.2:02 When the ignition button is pressed, an internal metal plate moves to bridge the connection between the battery and the starter motor.2:07 Repeated arcing during engagement and disengagement burns the surfaces of this plate and the two contact points, eventually creating a poor connection that prevents the starter from engaging.2:28 Because the plate rotates slightly during operation, the starter may work intermittently as it lands on clean or pitted surfaces.2:39 To repair the solenoid, disconnect the negative battery cable, remove the solenoid cover, and clean the contact points and plate using a file or wet-and-dry sandpaper.3:44 If the surfaces are severely damaged, flipping the plate or the contact bolts can provide a fresh connection surface.Watch This maintenance procedure avoids the expense of replacing the entire starter motor.0:07

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