Slave soleniod???

alamantia

Petty Officer 2nd Class
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Dec 16, 2011
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1987 Mercruiser 250/350. I see a slave solenoid mounted above my water separator. I see a solenoid on my starter. Seems a bit redundant. Is there a reason for doubling up? Just curious.
 

Don S

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Re: Slave soleniod???

Yes, it's there because of the long runs of small wiring from the engine to the helms ignition switch. Less amperage needed to operate the slave solenoid than to operate the starter solenoid.
 

alamantia

Petty Officer 2nd Class
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Dec 16, 2011
Messages
133
Re: Slave soleniod???

Yes, it's there because of the long runs of small wiring from the engine to the helms ignition switch. Less amperage needed to operate the slave solenoid than to operate the starter solenoid.

I see, so it just acts as a booster to insure the starter gets the amps it needs. That makes sense i guess. I guess if it was like an old ford, it may not even need one on the starter, which would be nice in a boat seeing as how hard it looks to change a starter in this thing.
 

Don S

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Re: Slave soleniod???

I guess if it was like an old ford, it may not even need one on the starter,

A Chevy starter uses the starter solenoid to engage the bendix into the flywheel ring gear.
 

matt167

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4,271
Re: Slave soleniod???

The system is favorable also because it leaves the starter completely dead instead of having power to the starter all the time... Ford in the early- mid 90's did the exact same thing. They abandoned their old starters which drove the bendix without the use of a mechanical solenoid in favor of a more conventional type starter but they remained using a fender mounted solenoid also.
 
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