Mid 1980’s Mercury 35 wire corrosion

[Drock]

I noticed the wire insulation and corrosion on these two wires today.
I don’t know much about outboard engines and think this is a switch box of some kind from searching boats.net for what this part is. So that’s how little I know.

Can anyone tell me how to fix this problem, nether the switch box or the wire harness is available from boats.net
The serial number on the engine is 6447291.
Thanks

 

[MDCrappie]

You need to clean off the corrosion and then cover the wire with something like liquid electric tape. The corrosion comes from the wire being exposed to moisture while current is flowing thru it. Can likely get an aftermarket switchbox, but not sure just replacing a working switchbox is a good idea.

Either of these is probably the correct replacement.

https://www.amazon.com/Jetunit-Outboard-339-7452A3-114-7452A2-114-7452A3/dp/B08QJ7QPF7

https://www.amazon.com/dp/B0CFGS5JZ...p_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM

 

[Drock]

You need to clean off the corrosion and then cover the wire with something like liquid electric tape. The corrosion comes from the wire being exposed to moisture while current is flowing thru it. Can likely get an aftermarket switchbox, but not sure just replacing a working switchbox is a good idea.

Either of these is probably the correct replacement.

https://www.amazon.com/Jetunit-Outboard-339-7452A3-114-7452A2-114-7452A3/dp/B08QJ7QPF7

https://www.amazon.com/dp/B0CFGS5JZ...p_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM

Thanks, would a spray for battery cable corrosion work or what about baking soda, a little water and a toothbrush clean it off?
Any other thoughts.

 

[MDCrappie]

I'd use vinegar, but I guess baking soda would work.

 

[Sea Antsy]

IDK what that is.. ? voltage regulator is my guess.. but based on the level of corrosion...
.. Now corrosion is not ON the wires.. it has ERODED much of the wire away...
..and the current (juice) carrying capacity of wire is based on it's thickness.. ie cross sectional area... yours is going, going.. and b4 it is GONE.. you should get a "B" plan in place..
If you can't identify/get one of those .."thingamajigs" whatever it is.. be prepared to Dremel away the plastic ends that was suppose to prevent the moisture from entering the wire jacket and "MINE" your way down to whole, shiny metal..and solder/add a conductor..and use marine grade wire that is tinned..
good luck..
and the liquid seal stuff is prob your best bet..

 

[Sea Antsy]

Humm wonder what that thing is.. hard to make out the colors.. but here is a link to mercury color code conventions from early 80's
https://maxrules.com/fixmercwiringcodes.html

 

[Seafarer]

Looks like a CDI module.
Those wires don't need insulating, they need to be replaced.
I'd cut back the harness until I got to clean wire and then solder and heat shrink on new leads and terminals. Use only tinned or marine grade wire, most likely 16 ga.
If you can't get back to good wire, then your looking at a new wiring harness.
In that case, get out the wiring diagram and make one up or spend the bucks for a new one from one of the aftermarket sources.

 

[Sea Antsy]

great detective work.. yea that's what it does look like..

I agree with everything ' cept the heat shrink tubeing on new leads and or terminals... IMHO heat shrink on wires only works on single strand wire and then only marginally. It cannot conform to the spaces between the individual strands well enough...
Heat shrink can't be water tight enough on multi strand conductors to keep out moisture.. the liquid stuff is much better.. if you want some abrasion resistance then put the heat shrink OVER the liquid stuff.

 

[MrGiggles]

Those seem to only be rotted near the ends, cut the bad out and splice in a new piece.

The wires are removable, there are nuts under those rubber caps. Just need a standard ring terminal for your new piece.

 

[LaqueRatt]

great detective work.. yea that's what it does look like..

I agree with everything ' cept the heat shrink tubeing on new leads and or terminals... IMHO heat shrink on wires only works on single strand wire and then only marginally. It cannot conform to the spaces between the individual strands well enough...
Heat shrink can't be water tight enough on multi strand conductors to keep out moisture.. the liquid stuff is much better.. if you want some abrasion resistance then put the heat shrink OVER the liquid stuff.

Not to be argumentative, but I disagree with most of this. Rarely do you find a solid wire on anything except house wiring. I think the key to success is having the correct size shrink tube. Properly applied, it has to be nearly waterproof. I've also been known to double shrink connections if there are multiple wires involved. I do like the liquid stuff too, but the crap gets hard in the bottle on you in like two shakes of a dogs tail. So, I'm always out. I substitute PlastiDip many times when I happen to have some of the crap that isn't also hard.

 

[MDCrappie]

Not to be argumentative, but I disagree with most of this. Rarely do you find a solid wire on anything except house wiring. I think the key to success is having the correct size shrink tube. Properly applied, it has to be nearly waterproof. I've also been known to double shrink connections if there are multiple wires involved. I do like the liquid stuff too, but the crap gets hard in the bottle on you in like two shakes of a dogs tail. So, I'm always out. I substitute PlastiDip many times when I happen to have some of the crap that isn't also hard.

Store it upside down. Lid will be a little harder to get off but it won't dry up. These lids, especially after using channel locks to get it open, will distort and then not be airtight when screwed on. This is why they dry up. If stored upside down a little bit will fill the void and make it airtight. I do the same with TruOil and PVC cement. Have had open bottles last years this way.

 

[lckstckn2smknbrls]

great detective work.. yea that's what it does look like..

I agree with everything ' cept the heat shrink tubeing on new leads and or terminals... IMHO heat shrink on wires only works on single strand wire and then only marginally. It cannot conform to the spaces between the individual strands well enough...
Heat shrink can't be water tight enough on multi strand conductors to keep out moisture.. the liquid stuff is much better.. if you want some abrasion resistance then put the heat shrink OVER the liquid stuff.

I believe shrink tubing now comes with adhesive inside.

 

[mirrocraft16]

There are all types of heat shrink tubing, the good stuff, generally sold as 'marine' or severe duty has what looks like hot glue inside it that melts when its heated.
Its 100% water proof.
The heat shrink tubing really doesn't touch the wire itself, its over the insulation and the terminal on each end.
I haven't checked lately but Napa used to carry the heat shrink with the glue inside.

Wires corroded that bad will likely be damaged or compromised pretty far up the harness, no just where the insulation rotted off them.
I cut back a chunk of harness the other day on a motor here and ended up just scrapping the harness, nearly ever last wire had green corrosion inside it, despite only have a few bare ends like that. $130 later and its good as new for another 40 years or so.

 

[Drock]

Store it upside down. Lid will be a little harder to get off but it won't dry up. These lids, especially after using channel locks to get it open, will distort and then not be airtight when screwed on. This is why they dry up. If stored upside down a little bit will fill the void and make it airtight. I do the same with TruOil and PVC cement. Have had open bottles last years this way.

Is there a way to thin the stuff when it get thicker?

 

[MDCrappie]

Is there a way to thin the stuff when it get thicker?

I've never tried, but doubt there is. It's vinyl I believe.