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scondary starter solenoid??

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chrisfiat

Contributing Member
I have a 1989 stingray with a 165 hp 4 cyl mercruse 470, and i am wondering just what is the purpose on the secondary starter solenoid, seems to me to be just another component to fail.
oh and can someone point me to a wireing diagram for this setup.

thanks
chris
 
...what is the purpose on the secondary starter solenoid...
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The key switch sends voltage to the primary solenoid which energizes and sends direct battery voltage (high current) to the starter solenoid which pulls/turns the starter armature into the flywheel to turn the engine.
 
so why not just put the key switch directly to the starter solenoid, as in an automotive application???? it would seem to be another failure waiting to happen in the system
 
the problem is the wiring in boats is too small to carry that current, thats why a remote is used.remotes also used for trim motors, anchor winches,etc.
 
Bt Doctur said:
the problem is the wiring in boats is too small to carry that current, thats why a remote is used.remotes also used for trim motors, anchor winches,etc.
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uh no. the remote solenoid is 4 inches away from the starter so that is not the issue here. what has happened is this. This engine originally came with a starter that had NO solenoid installed, so a remote one was used, when the starter failed and was replaced someone just wired up the original solenoid to the solenoid on the replacement starter. now as a side issue this wire harness has a 12 volt feed that goes to the coil during engine cranking. after start the power to the coil is taken off the choke heater wire through a resistance wire to the coil b+ terminal
since there is no internal resistor in the coil .
 
I have a 1977 ranger with a 4 cyl volvo that I bought new. It used to not turn over sometimes when the engine was hot. After having the starter checked out a couple of times, a tech there told me to mount another solonoid nearer the engine. He said the longer ignition wires from the front of the boat to the engine couldn't handle the current. After about 30 years running this way. I have never had a problem and haven't had to replace either solonoid. Delfinately leave it like it is.
 
SibetOR said:
I have a 1977 ranger with a 4 cyl volvo that I bought new. It used to not turn over sometimes when the engine was hot. After having the starter checked out a couple of times, a tech there told me to mount another solonoid nearer the engine. He said the longer ignition wires from the front of the boat to the engine couldn't handle the current. After about 30 years running this way. I have never had a problem and haven't had to replace either solonoid. Delfinately leave it like it is.
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so now the "longer ing wires " are about 6 inches shorter think about that for a minuet, your problem was either a failing solenoid or bad connections that were " cleaned up with the installation of the solenoid
 
chrisfiat said:
uh no. the remote solenoid is 4 inches away from the starter so that is not the issue here. what has happened is this. This engine originally came with a starter that had NO solenoid installed, so a remote one was used, when the starter failed and was replaced someone just wired up the original solenoid to the solenoid on the replacement starter. now as a side issue this wire harness has a 12 volt feed that goes to the coil during engine cranking. after start the power to the coil is taken off the choke heater wire through a resistance wire to the coil b+ terminal
since there is no internal resistor in the coil .
Click to expand...



UH NO!!!!!!!!!!!

Every marine engine I have ever worked on has a SLAVE solenoid.

Where ever you got the senerio of a nonsolenoid starter and "someone" added a starter with one and left the original remote starter solenoid there I have no idea!!

It is true the older 170/470/whatever the bastard merc motor was called, did come with a NON attached solenoid starter but in later years they did go to one with a starter solenoid attached to the starter.

All 4 cyl, 6, v6, v8 have a slave solenoid.

My opinion of why,

lets say you have a 27 ft boat, how long would the wire coming from the ignition switch have to be to reach the starter mounted solenoid? ~ 30 ft long. The voltage drop would be way to much to activate the solenoid properly every trime and the comment of small wire diameter would be true here. Thus the slave solenoid. the coil of the solenoid only needs to be activated from the key switch and would require less current!!
The slave solenoid now transfers high current to the starter mounted solenoid with ~ 3 feet of wire in the engine wire harness.

With the exception of the older non solenoid mounted starters.........which by the way were only used on point ignitions and were basically a ford starter solenoid. The mounting tab was ground. Current slave solenoids have the ground as one of the coil terminals......


Mercury does not know what boat/legnth a motor will be installed into. A 30 ft boat could have two 470's or two inline four cylinders....
 
the slave solenoid is 4 inches away from the starter solenoid . that will have essentially NO effect on the voltage drop from the key switch. so far no one has yet come up with a compelling reason to operate a solenoid with a solenoid 6 inches away, the differences in voltage drop will be unmeasurable
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I have a 1989 stingray with a 165 hp 4 cyl mercruse 470...
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Correct me if I'm wrong but didn't Merc. stop building the 470 in the mid 1980s? It sounds like sombody stuck a salvaged 470 into your boat sometime after the original engine puked...thus all the solenoid hoopla.
 
I have your answer.

1. 1989 was the last year of that motor. I have the manual.

2. it was configured the way it is.

3. if you do not like it then change it to what you like and see what happens.

4. my answer is still the correct one as far as I know.

SEE ATTACHED!!!!!!!!!!
 
chrisfiat said:
the slave solenoid is 4 inches away from the starter solenoid . that will have essentially NO effect on the voltage drop from the key switch. so far no one has yet come up with a compelling reason to operate a solenoid with a solenoid 6 inches away, the differences in voltage drop will be unmeasurable
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It makes sense given that the slave solonoid requires less current to operate than the solonoid mounted on the starter. If they both drew the same amount of current, then your statement would make sense about there being no benefit for the slave unit. However, 6 inches or 6 feet away, it still saves the boat manufacturer money in production wiring by having a slave unit there, and that's what it's all about. The bean counters will figure this out down to the penny per unit produced. Kghost also brought up the point: "Mercury does not know what boat/legnth a motor will be installed into. A 30 ft boat could have two 470's or two inline four cylinders...." Makes total sense given the differences in loads noted above.
 
Well. You seem to have the answers. I suggest taking off the extra seloniod, and give it a try. Hope you don't need a tow. I will leave mine just like I set it up.
 
Chris, With keeping an open mind on this subject, in the link below it appears yanmar may have had a few issues in their starting system from what appears to be from neglecting to install a standard starter slave solenoid in their starting system.

http://www.sailnet.com/forums/gear-maintenance/44174-3gm-engaging-starter-idiosycrasies.html

Now it's hard for us to say if something like the above link would happen within your particular engine starting system, but i'm pretty sure a company like merc, volvo, etc, etc, has probably done enough research by now to know if they would want to afford installing an extra part such as something like this on their engines or not, Especially without knowing what the boat application is going to be exactly.
 
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