Starter Motor Replacement Or?

[Richard Seccombe]

Hi Everyone,

I have a 400 Express Trojan with 2 Mercruiser 8.1 S engines. One starts just fine cold. The other one does the normal beep and I hear the fuel pump light up when I turn on the ignition, and I hear a good "Click" which leads me to believe that the solenoid is operating but the starter motor doesn't fire up. If I hold the start button for a little while a few times it will eventually turn over and the engines starts fine. If I run that engine for a little while, shut it down, and try to restart it, it will fire right up.

I checked and cleaned the leads to the start switch, the solenoid and the starter itself. All of them looked good even before I cleaned them. I konw the batteies are good becuase the other engine fires right up.

I'm guessing it's new starter motor time but it's strange that it work well after everything has warmed up.

Any suggestions would be very much appreciated.

Thanks,
Richard

 

[Bondo]

Re: Starter Motor Replacement Or?

I checked and cleaned the leads to the start switch, the solenoid and the starter itself. All of them looked good even before I cleaned them. I konw the batteies are good becuase the other engine fires right up.

Ayuh,... What about the Ground path,..?? It takes 2 legs to stand....

 

[Bt Doctur]

Re: Starter Motor Replacement Or?

what about the slave solenoid?

 

[JustJason]

Re: Starter Motor Replacement Or?

and I hear a good "Click" which leads me to believe that the solenoid is operating but the starter motor doesn't fire up

The only way you can make that assesment is to do a point to point voltage drop test across the entire starting system... Then you will know what is good and what is bad.

 

[Richard Seccombe]

Re: Starter Motor Replacement Or?

Thank you for the information. Most of my experience is wth older car engines. What is a "Slave Solenoid", what is its purpose, and most of all, where is it located on a Mercruiser 8.1S engine?

I come from the old days of the only solenoid being mounted on the top of the starter motor.

Thanks,
Richard

 

[6meter]

Re: Starter Motor Replacement Or?

It looks like the old Ford starter soleniods. Should be attatched to the motor somewhere. Juice goes from key switch to slave sol to starter sol.

 

[Bondo]

Re: Starter Motor Replacement Or?

I come from the old days of the only solenoid being mounted on the top of the starter motor.

Ayuh,... The Slave delivers cleaner power to the exciter wire of the solenoid, by-passin' the Long trip to the key,+ back...

 

[JustJason]

Re: Starter Motor Replacement Or?

Also Makes for easier wiring to by the engine installer at the boat manufactoring plant... by using a slave they don't have to get into the engines wiring harness and screw something up.

 

[Richard Seccombe]

Fixed and running!

Fixed and running!

Thanks for all of the assistance everyone.

I took your advise and also printed up the step by step sequence that Don has posted, bought a 12 volt test light and headed to the marina.

I started by locating the slave solenoid and cleaning each contact. They actually looked very good but I polished them up anyway. I hit the start switch and the engine fired right up. No parts, no marine electrician, and a much better understanding of all of the components that get an engine started.

You got ta love this forum!

Thanks again,
Richard