Ground wire corrosion in outboard

[pda]

Hello,

I noticed that the ground wire mount in my outboard has corrosion on it. It appears to be falling/dripping down onto the oil filter platform and corroding that as well.

I looked all around in the outboard and find no other issues, and there is no corrosion on either of the battery terminals or anywhere else in the boat's electrical system that I can find.

Any ideas on what is causing this or know how I can fix this? My fear is that it is slowly destroying the oil filter area and everything below it.

 

[Hookup1]

Take it off, wire brush it, wipe down with dielectric grease (Autozone) and re-install it. Check positive lug too. The corrosion should affect anything else. Blow it out or vacuum. Check it again mid-season and at the end.

I don't see any evidence of salt spray. You should be fine.

 

[Halfhitch]

....and keep the whole under-cowl powerhead sprayed with a light weight lube/corrosion inhibiter. Here's a link to one expensive one. WD40 works fine, but doesn't last quite as long.

https://www.amazon.com/Yamashield-Rust-Corrosion-Protectant-12Oz/dp/B008KYTZQ8/ref=sr_1_1?crid=3EOVZTUB1OXAJ&keywords=yamaha+corrosion+spray&qid=1679132756&sprefix=yamaha+corosion+,aps,98&sr=8-1

 

[seasick]

I don't use WD40. I would use Boeshield T-9. That stuff is good for fuse blocks and the like also.
I also have to disagree about dielectric grease. It is an insulator and is not recommended for use on the mechanical connections of conductors. That means it is not intended to be spread on the contacts side of things like your battery cable and motor casting. Clean those surfaces, make a good mechanical connection and then lightly spray the T9 on the assemble to provide a corrosion resistant coating.

 

[billbass]

I don't use WD40. I would use Boeshield T-9. That stuff is good for fuse blocks and the like also.
I also have to disagree about dielectric grease. It is an insulator and is not recommended for use on the mechanical connections of conductors. That means it is not intended to be spread on the contacts side of things like your battery cable and motor casting. Clean those surfaces, make a good mechanical connection and then lightly spray the T9 on the assemble to provide a corrosion resistant coating.

I would disagree. Dielectric (DE) grease is just a useful grease used as a coating to protect from corrosion and that has no conductivity. With a metal to metal contact, as in that photo, any DE grease between the surfaces should not cause a problem. I suggest removing all battery and high current connectors, cleaning all surfaces and coat all surfaces with DE grease. When such a connection is tightened the excess grease will squeeze out where the metal needs to touch other metal for conductivity but the excess will still create an anti-corrosion barrier where there is no metal to metal contact. The dielectric grease acts to keep corrosion from occurring and this seems like a good application and need. I am surprised at the corrosion shown in the photo. It's odd that this is all you are seeing and its also odd that its white or silver in color. (I would not worry about the oil filter. You change that at least every 12 months and that flaked off oxidized material isn't going to hurt much. The condition may be due to galvanic action. You may have some unusual grounding problem. Do some research on that topic.
Here's a page on dielectric grease: https://www.thedrive.com/maintenance-repair/39173/dielectric-grease. It says: "Dielectric, sometimes referred to as tune-up grease, is a viscous non-conductive waterproof substance used to protect electrical connections from corrosion and dirt."

 

[billbass]

CRC makes a good corrosion inhibitor also

 

[DennisG01]

Clean and protect and you should be fine. Clean all the metal surfaces real well... I almost wonder if there was a fragment/sliver of another metal in there. I think you'll find once you clean off the oil housing that it's totally fine, too.

Seasick/Bill... you guys are both right. Dielectric is, by definition, non-conductive - meaning, it should not be used between electrical connections. However, it's perfectly fine to slather it on after the connection is made. That's the intended purpose of it. Now, in real life, and in this situation, a light, LIGHT coating of it on the surfaces before mating is going to be OK. In the lab, no - but in real life it works fine. That said, best practice is still to put it on AFTER the connection is made.

I'm a big fan of Boeshiled T9 - it's like Frank's RedHot for me -- if you've seen the commercials, you get it

 

[DennisG01]

Oh... a little more on dielectric. The reason a very light coating tends to be fine in real life is because of the microscopic surface imperfections (more on this below) of the two mating surfaces and also that we're not dealing with highly sensitive electronics here - the computer is sensitive, but not "highly" sensitive like some lab equipement may be. The microscopic pores will get fileld with the material, preventing a spot for corrosion, while in other places it will squeeze out enough to not be of concern.

As far as insulating products go... Tef-Gel is the king. Crazy expensive, but it's top notch. I once called them and asked them about the insulating thing and using it between connections as they actually promote that. That's where the microscopic comment came from above - I'm not smart enough to figure that out myself But, they did say that their product has much smaller molecules in it and is much better suited to be used in that way than typical dielectrical grease.

It was a good conversation and they were very informative - I could tell the guy I was talking to knew a heck of a lot more than me. Yes, I bought a container of Tef-Gel and I do use it A tiny brush works really well - a little bit of that stuff really does go a long way. Over time, I've found it lasts much longer than dielectric, too. I don't "not" use dielectric - but when I can, I use Tef-Gel......... an then I use Boeshield like it's going out of style over everything....

 

[SkunkBoat]

I think you guys are arguing the same point. All of the things you guys listed are "dielectric" whether its a grease or spray. And you can use them on electrical contacts like battery terminals, power plugs, trailer light plugs, slip rings.......Thats what they are for. In the Navy we sprayed or wiped that shit on everything.

I spray my motors with CRC silicone.

I agree that that is unusal corrosion, especially on a ground or Neg connection.

 

[billbass]

Clean and protect and you should be fine. Clean all the metal surfaces real well... I almost wonder if there was a fragment/sliver of another metal in there. I think you'll find once you clean off the oil housing that it's totally fine, too.

Seasick/Bill... you guys are both right. Dielectric is, by definition, non-conductive - meaning, it should not be used between electrical connections. However, it's perfectly fine to slather it on after the connection is made. That's the intended purpose of it. Now, in real life, and in this situation, a light, LIGHT coating of it on the surfaces before mating is going to be OK. In the lab, no - but in real life it works fine. That said, best practice is still to put it on AFTER the connection is made.

I'm a big fan of Boeshiled T9 - it's like Frank's RedHot for me -- if you've seen the commercials, you get it

I'd disagree with "still to put it on AFTER the connection is made.". Putting it on exterior surfaces after making the connection is great. However, you do also want it between the metal to metal mating surfaces. Corrosives are gases or extremely small particles of salt or salty air and or acid from the battery. You want that protective coating on all metal surfaces and most especially on the metal to metal surfaces where you want electricity to flow. between one metal part and another, without compromise.

 

[DennisG01]

I'd disagree with "still to put it on AFTER the connection is made.". Putting it on exterior surfaces after making the connection is great. However, you do also want it between the metal to metal mating surfaces. Corrosives are gases or extremely small particles of salt or salty air and or acid from the battery. You want that protective coating on all metal surfaces and most especially on the metal to metal surfaces where you want electricity to flow. between one metal part and another, without compromise.

We're splitting hairs here. Technically, Seasick is 100% correct - it is an insulator and should not be used between electrical connections. That part is true and fact. That was why I said "best practice". But in reality, a SMALL/VERY THIN amount works fine for this application. That was why I said "in real life".

Using your words of putting it "between" the surfaces isn't entirely correct because the distinction needs to be made to NOT put heavy coat on. Chances are, it will all squeeze out and not cause a problem here because it's not an overly sensitive connection. The proper thing is to add the words "thin coat" to the directions... in other words, splitting hairs... and I am pretty darn sure you didn't mean to insinuate globing it on

 

[pda]

Thank you everyone, I have cleaned this connection up and applied the dielectric grease. It cleaned up real easily.

Here is a photo of the oil filter base, you can see what the corrosion flakes are doing to it.

I'll keep an eye on this over the season. The boat stays in the water for about 5 months a year.

 

[SkunkBoat]

Its gotta be salt?

 

[pda]

Its gotta be salt?

Could be, but not sure how it would be collecting on just this lug and no where else.

 

[SkunkBoat]

Could be, but not sure how it would be collecting on just this lug and no where else.

yes, very strange. But the fact that it fell and then corroded near the oil filter means its corrosive in itself.

Maybe some odd drip from the cowling? Maybe put a paper towel there then put cowling back on and hose the crap out of the motor. See if you get a drip.

 

[Meanwhile]

yes, very strange. But the fact that it fell and then corroded near the oil filter means its corrosive in itself.

Maybe some odd drip from the cowling? Maybe put a paper towel there then put cowling back on and hose the crap out of the motor. See if you get a drip.

Make sure the drains in the cowling are open. Mine were clogged with salt & crap. Another thing to check.

 

[Fishtales]

Take it off, wire brush it, wipe down with dielectric grease (Autozone) and re-install it. Check positive lug too. The corrosion should affect anything else. Blow it out or vacuum. Check it again mid-season and at the end.

I don't see any evidence of salt spray. You should be fine.

Agree. Can spray it when done with some CRC corrosion inhibitor if you have it as well.

 

[Hookup1]

Make sure the drains in the cowling are open. Mine were clogged with salt & crap. Another thing to check.

Cowling drains can be a big problem. They either clog or the zinc material corrodes. Should be checked and snaked out with 300 mono. While you are at it do the fuel cooler and tell-tale drain. Every season.