Starter slave solenoid

[robcripe]

On a 1975 Mercruiser 165, what is the starter slave solonoid for?? The Starter itself has a solenoid and the slave solonoid is just wired to it, WHY??? Just seems like extra parts to go wrong to me

 

[Bt Doctur]

Re: Starter slave solenoid

The wiring in a boat is too small a gauge to properly power some items. slaves are used for this purpose.low powered circuits to operate higher powered circuits.

 

[robcripe]

Re: Starter slave solenoid

But this is not the case in this instance! The battery main lead is wired directly to the starter solenoid. The key switch is wired to the slave solenoid. This draws absolutely no more power than wiring the key switch directly to the starter. The rest of the boats electrical circuit is completely independent of this system.

 

[Bondo]

Re: Starter slave solenoid

But this is not the case in this instance! The battery main lead is wired directly to the starter solenoid. The key switch is wired to the slave solenoid. This draws absolutely no more power than wiring the key switch directly to the starter. The rest of the boats electrical circuit is completely independent of this system.

Ayuh,... Welcome Aboard,... The Key alone won't supply sufficient power to the solenoid to to engage it....
The slave solenoid, Does...

 

[Don S]

Re: Starter slave solenoid

The slave solenoid or relay is used by all marine engine manufacturers. While the wiring to the switch and back to the engine is fine when new, but connection can corrode over time and may not supply enough amperage to pull in the starter solenoid, especially on very long runs of wire found on some boats. So they install the relay or solenoid because it takes a LOT less current to activate that the starter relay.
When the engine manufacturer produces the engine, they have no way of knowing what boat it will go in, or if there will be a long run of wire to the key switch or short run, so they make them to cover all cases.

If yours works without the solenoid, and you don't want to use it, then bypass it. No big deal.

 

[robcripe]

Re: Starter slave solenoid

I am rewiring the whole boat so I am going to run a size bigger wire and get rid of the slave solenoid, am also getting rid of the key switch and installing toggle switches. I also do not like how the rest of the boat is always hot so I am installing a master solonoid for all power except the bilge pump and anchor light.

 

[Bondo]

Re: Starter slave solenoid

I am rewiring the whole boat so I am going to run a size bigger wire and get rid of the slave solenoid, am also getting rid of the key switch and installing toggle switches. I also do not like how the rest of the boat is always hot so I am installing a master solonoid for all power except the bilge pump and anchor light.

Ayuh,.... Why not just use a battery selector switch, like most boats....

I hope yer redesigns live up to yer expectations...

 

[stonyloam]

Re: Starter slave solenoid

Just remember, the the resistor wire bypass for the coil (provides 12V directly to the coil when starting) on most 470's is from a set of points in the slave solenoid and you will have to rewire that properly or your engine will not start.

 

[Don S]

Re: Starter slave solenoid

Just remember, the the resistor wire bypass for the coil (provides 12V directly to the coil when starting) on most 470's is from a set of points in the slave solenoid and you will have to rewire that properly or your engine will not start.

He has an inline 6 from 75 Terry, the 470 style 165 didn't hit the market till 87.

 

[robcripe]

Re: Starter slave solenoid

I went ahead and installed the slave solonoid and have the wiring finished up.