Can you tell me what this wire is for?

[SsendaM]

This is a 2005 Mercury 8hp 4stroke, Pull start. The wire has separated near the bolt and thought someone could tell me what this wire is used for..perhaps a sensor? Thanks for looking.

[Mordalphus]

Looks like a ground wire. I'm probably wrong though

[SsendaM]

That was my guess as well but I can't think of anything that would require electricity down there... It will have to be fixed before the weekends derby, but it would be nice to know more about this.

[MarkFromSea]

grounding of sorts.... it's so electricity(static, dissimilar metals, leak, or whatever) passes through the wire instead of the fitting, bolts or in your case it sorta looks like an O ring fitting(picture, hard to tell). It helps ensure the electricity eventually passes to you zincs(sacrificial metal). To understand some of that, google: galvanic corrosion, dissimilar metals and the importance of zincs on vessels or boats.... google them separately..... It's all good info!

[Bodofish]

Definite ground wire. Looks like it's being used to ground the different parts of the motor together.

[G-Man]

grounding of sorts.... it's so electricity(static, dissimilar metals, leak, or whatever) passes through the wire instead of the fitting, bolts or in your case it sorta looks like an O ring fitting(picture, hard to tell). It helps ensure the electricity eventually passes to you zincs(sacrificial metal). To understand some of that, google: galvanic corrosion, dissimilar metals and the importance of zincs on vessels or boats.... google them separately..... It's all good info!

That is a pretty good description of its purpose which is to keep all the metal parts at the same potential. The most accurate term would be a bonding wire/connection.

[AJ's Dad]

Heres a link to a schematic of an 8 hp 4 stroke merc. Item 23 says its a ground cable.

http://www.boats.net/parts/search/Merc2 ... parts.html" onclick="window.open(this.href);return false;


Hope this helps

[hewesfisher]

It's a ground wire, but be very careful when you remove the grease zerk to replace that ground wire. That zerk has a unique thread and I had to special order a replacement when I snapped the barrel portion off with my grease gun.

[Amx]

If you'd rather you can drill and tap another hole just for the wire. Won't be breaking the grease fitting that way. It looks a little corroded and just might break off.

[SsendaM]

Thanks for the quick and detailed responses guys, I learned a thing or two. Good luck on the water this year.

[MarkFromSea]

G-Man has the more correct term>>>> Bonding
http://en.wikipedia.org/wiki/Electrical_bonding" onclick="window.open(this.href);return false;

[Idstud]

Well everyone agrees its a ground wire. Not just for corrosion but could have been set up for a Black box on a fiber glass boat to ensure for a good ground so the electricity would travel properly through the down rigger cables.

[Bodofish]

Naw standard fair on a Merc., Mines has one too and it joins all the metal bit together. And the ignition is also grounded to the lot.

[MarkFromSea]

Well everyone agrees its a ground wire. Not just for corrosion but could have been set up for a Black box on a fiber glass boat to ensure for a good ground so the electricity would travel properly through the down rigger cables.

On this one, I must disagree...... That wire is solely for corrosion protection, solely to protect the motor from damage caused by electrolysis. That manufacturer installed wire is to protect the manufacturers engine and good name. Damage occurs very quickly in salt water(electrolyte), and, with out a clean zinc, you may as well throw the outboard away after a year of hard use in salt water...

I'm not saying that to be an ass, just is!

[MarkFromSea]

The parts are bonded, the ignition is grounded to the bonded parts........ semantics to a point but there is a difference, sorta like a neutral wire vs ground wire in home wiring.....

[SsendaM]

I unscrewed the zerk bolt and replaced the U connecter to the wire and everything looks to be in working order... I appreciate all the feedback. Now MarkFromSea brought up the fact of using Clean Zincs in saltwater, that clicked in my head so I had to go look at my boat again... When exactly should a zinc be replaced? I use in salt about a month a year which includes trolling with my kicker. I looked at the two zincs on both sides of my main engine(2002 merc 125) and they look like their doing their job, as if someone took a shotgun to it yet I believe there is a adjustable zinc triangle fin above the prop that appears untouched..? furthermore I have two round disc Zincs that are mounted on the hull brackets that do not have any damage AND my kicker has a rotating fin like the one described with my main engine that appears untouched but no zincs anywhere else... So I am confused now why the only zinc that is being damaged is the two block eraser sized zincs on my main engine?? I hope I didn't make this more complicated than it needs to be, haha. Thanks again guys and If I need to post pics of the zincs or should open a new post just let me know. I forgot to mention I believe the wire broke free after I took it out of salt water but I could be wrong...

[Bodofish]

Galvanic corrosion is kind of funny like that. It'll pick a spot it likes to go and that's just the way the electrons flow. At about 1/4 of the "zinc" left you may want to go ahead and just replace them, it's all about the surface area. They aren't really zinc on your motor, the correct term for them would be "anodes", they got the term "zinc" because they are made of zinc on a steel boat (think big). So your eraser shaped anodes are most likely magnesium as they're there to protect the aluminum. The little skeg fin is probably zinc and as such won't sacrifice itself nearly as fast as the magnesium.

[SsendaM]

That makes sense considering they are all connected to each other and all the other Anodes look like a harder metal than the one that's being affected. Thanks

[MarkFromSea]

Galvanic corrosion is kind of funny like that. It'll pick a spot it likes to go and that's just the way the electrons flow. At about 1/4 of the "zinc" left you may want to go ahead and just replace them, it's all about the surface area. They aren't really zinc on your motor, the correct term for them would be "anodes", they got the term "zinc" because they are made of zinc on a steel boat (think big). So your eraser shaped anodes are most likely magnesium as they're there to protect the aluminum. The little skeg fin is probably zinc and as such won't sacrifice itself nearly as fast as the magnesium.

Good point! It's kinda funny when people paint em! (big boats)

[SoDakboy]

I'm a submariner and our zincs are 12x4x4" they look like white bricks and they are everywhere.