How to tell if outboard is salt or freshwater

[RuthlessINXS]

I bought a pontoon that came with 1980 Mercury 80EL outbaord. I know it has been used exclusively in freshwater but I wanted to know how to identify it as either freshwater or saltwater outboard or even if there was a differentiation in the motors back in 1980. Thanks for the help.

 

[Scott Danforth]

Re: How to tell if outboard is salt or freshwater

it the motor was bought new and dunked in salt water, it was used in salt water. if a motor was bought new and dunked in fresh water, it was a fresh water boat.

Mercury did offer a "salt water series" however that was a larger outboard and a sales/marketing name

 

[coastalrichard]

Re: How to tell if outboard is salt or freshwater

And the modifications made to the Saltwater Series were very few and minor.

 

[RuthlessINXS]

Re: How to tell if outboard is salt or freshwater

So as long as i continue to flush it after runs it should be fine?

 

[minuteman62-64]

Re: How to tell if outboard is salt or freshwater

Here in San Diego I routinely see 30-40 year old motors that have been exclusively (or almost exclusively) used in salt water. I'm sure there are more maintenance issues that if a motor was used only in fresh water, but they are managable. If yours has been used exclusively, or almost exclusively in fresh water, keep up the maintenance and enjoy it for the next 10-20 years

 

[1stgenbird]

Re: How to tell if outboard is salt or freshwater

I have a 1984 Mercury 9.8 outboard that was purchased new by my father and used on the skiff he towed behind his cruiser on Cape Ann off the coast of MA for many years. As the skiff was trailered, he always did a fresh water flush when bringing the motor home. I now use it on my 14' Starcraft tinny in both fresh and salt water. Matter of fact I just returned yesterday from 2 weeks in Nova Scotia where I had my boat tied up to a salt water dock the entire time. Today I ran it in a barrel and flushed it out. The outboard is in excellent cosmetic condition and runs great. I know from reading other questions that some have the idea that a motor used in salt water just corrodes away but that isn't the case with proper care.

 

[Chris1956]

Re: How to tell if outboard is salt or freshwater

The "saltwater" models came out years after that motor was made. I never thought it was more than a marketing thing.

Your motor will have a SS driveshaft, which is a plus. On those old inline motors the salt eventually (25+ years) rotted out the exhaust cover components. If your motor is mostly freshwater, you will not have an issue.

 

[Scott Danforth]

Re: How to tell if outboard is salt or freshwater

I just spent the afternoon working on a 1998 40 hp Merc. that was only used in salt water. the motor was never flushed, nor covered. the issues were ethanol fuel deteriorated in the lines and faded paint due to the sun.

you will be fine with your motor in salt water, even if you flush it or not.

 

[wired247]

Re: How to tell if outboard is salt or freshwater

Saltwater series motors just had a few sacrificial anodes here and there. Had nothing to do with the motor itself per se.. Bottom of the mounting bracket, the trim tab and a piece that clamps through the lower were made of zinc and should be unpainted for them to work. .

 

[RRitt]

Re: How to tell if outboard is salt or freshwater

if you use your outboard in saltwater then the key to longevity is wash, flush, grease, and anodes.

The white powder you see is not salt residue. It is aluminum oxide caused by the interaction of stainless, iron, aluminum, and saltwater. The hard metals will remove electrons from soft metals if the water conducts electricity. If aluminum is your softest metal then it gets messed up. Anodes need to be a softer metal than aluminum and they need to be healthy metal. Don't wait for your anode to fall apart before replacing it. replace it as soon as it starts losing its ability to dump electrons into salt water.

now, the problem with aluminum oxide is that is is 10x larger than the aluminum and it's favorite placer to form is in the spaces between SS bolts and aluminum threads or SS shafts and aluminum blocks. It causes your engine to turn, rotate, lift stiffly and it causes bolts to become seized into the holes. SS is a very hard metal and when a bolt snaps then replacing it becomes a major headache. The net effect is that your engine will take 8 hours to do a 2hour maintenance job.

 

[emoney]

Re: How to tell if outboard is salt or freshwater

It's already been said, so at the risk of being redundant; I spoke with a person that worked at Mercury and the "Saltwater Series", as mentioned, was basically a sticker and two anodes placed on the LU. Everything else was exactly the same. Like you've been told, the key is maintenance, which is no different regardless of what type water you use it in. Every motor I've owned for the past 14 years has been a "salt water motor", but none of them said so. Living on the Gulf of Mexico, you kinda don't have any choice. Congrats on the new boat and welcome to iboats!

 

[wired247]

Re: How to tell if outboard is salt or freshwater

Thats not how sacrificial anodes work. It has nothing to do with the softness or hardness of the material. Think of your motor as a battery with the electrolyte being saltwater. The zinc sacrificial anodes have a reduction potential lower than that of aluminum oxide and corrodes before the aluminum oxide even begins to corrode. The zinc ions more attractive than the aluminum oxide ions to the electrolyte.

BTW.

if you use your outboard in saltwater then the key to longevity is wash, flush, grease, and anodes.

The white powder you see is not salt residue. It is aluminum oxide caused by the interaction of stainless, iron, aluminum, and saltwater. The hard metals will remove electrons from soft metals if the water conducts electricity. If aluminum is your softest metal then it gets messed up. Anodes need to be a softer metal than aluminum and they need to be healthy metal. Don't wait for your anode to fall apart before replacing it. replace it as soon as it starts losing its ability to dump electrons into salt water.

now, the problem with aluminum oxide is that is is 10x larger than the aluminum and it's favorite placer to form is in the spaces between SS bolts and aluminum threads or SS shafts and aluminum blocks. It causes your engine to turn, rotate, lift stiffly and it causes bolts to become seized into the holes. SS is a very hard metal and when a bolt snaps then replacing it becomes a major headache. The net effect is that your engine will take 8 hours to do a 2hour maintenance job.

 

[RRitt]

Re: How to tell if outboard is salt or freshwater

It is not meant to be a technical explanation. It is meant for the average boater who likes to drink beer, ski, and fish.

Electrons get sucked out of the softest metal. Stainless sucks them out of aluminum. If you have some zinc then aluminum will suck them out of zinc. If your zinc gets used up then your aluminum gets fubar.

See? that's a lot easier to remember than cathodes, anodes, galvanic potential, nobility charts, and ions.