Merc 700 starter solenoid issues

[Ashburn448]

Hi everyone, I've read a lot here but new this is my first actual post, seems like there's a lot of knowledgeable people on here and I'm hoping I can get some advice on my situation. So I have a 1959 cutter with a 1961-62 mercury 700 full gear shift short shaft motor serial number 1482689. I purchased the motor recently and it ran when I bought it but I had a couple issues once it was on the boat. The starter at first would spin but not engage flywheel. I checked bendix and lubed, checked all connections and eventually purchased a new battery. After the battery I was able to start the motor a few times but then the starter solenoid stopped working. Would not click or anything even thought it was receiving voltage. I jumped the two large wires on solenoid to check starter motor and it started every time without issue. So now for the real issues, I purchased a new old stock starter solenoid and installed it. At first it seemed like everything was fixed. The engine cranked every time with the key and then turned on. Unfortunately the starter would not shut off after engine was running. Then when I tried to shut engine off with key it still did not shut off the starter motor or the engine. Had to pull battery cable to stop it. This issue reoccurred every time I started the motor. I then disconnected the red wire leaving the solenoid and going to starter motor so I could test the solenoid. When I turn the key all the way to crank the solenoid clicks and sends 12v volts out, when. I release key the solenoid contacts open, as the should, and I have zero volts again. I tested the solenoid many times without starter motor connected and cannot get it to malfunction at all. But every time it's hooked up the starter continues to spin after engine catches and key is released and every time I can not shut off engine or starter with key. Sorry for the ridiculously long post, please let me know if anyone has any advice or I left out any important information

 

[alldodge]

Not an OB guy but maybe my comment will help and even bring in someone else.

Don't know your start but most have springs to retract the starter gear and disengage the gear. Since its not retracting (or is it) then maybe the spring is broken or no longer strong enough to retract

 

[sam am I]

Diffidently could be as Dodge says but, I'd wager 2 bits the solenoid contacts are worn (see below) and the plunger (middle pic) is hanging up in the grooves....If the plunger hangs in the contact groove, the starter will continue to run when the key is shut off.

This groove coupled with the initial arc the plunger makes a small'ish weld forms upon each contact, when this groove forms it tends to make a higher level of "sticking" occur due to the plunger's edge dropping down into the worn depression area of the contact.

A un-loaded bench test doesn't necessarily create the same welding amount of heat so the problem can mask itself on a bench.....

Just a theory however, my thesis wasn't solenoids

 

[Ashburn448]

Thanks for the responses guys! Dodge I did have problems with the starter motor originally but after replacing the solenoid and battery that operated correctly. Sam I thought that same thing as you and purchased another brand new solenoid after the new old stock one thinking that after sitting for years somewhere that one was sticking. Unfortunately it did not solve the problem. After some further inspection today I believe I found that my red wire from my rectifier is shorting to the yellow that goes to my solenoid. So when the engine cranks and starts up the motor is now supplying voltage to my solenoid and keeping those contacts closed! I ohmed out everything and found that I have continuity between B and F at all times through my controls harness when disconnected from outboard. Believe this might be an ignition switch issue??

 

[Ashburn448]

Thanks again for the help, I found the last issue. The red wire coming from my rectifier was connected to my orange wire going to my solenoid coil at the ignition switch. So when the motor cranked over and started generating it's own voltage it was constantly supplying it to the solenoid and keeping it closed. At some point someone replaced the ignition switch and apparently wasnt too careful about wiring it back in the right way.