How to reduce saltwater damage?

relics hunter

Petty Officer 2nd Class
Joined
Jun 11, 2010
Messages
118
I have two Johnsons a 1988 6hp and a 1979 35hp that get subjected to saltwater a couple times a month on average. I have done a lot of work on them and would like to somehow protect them as well as I can. I do the usual flush at home to clean the innards out, sometimes I can launch up river and flush on the way back. I hose off the motor along with the boat and trailer. I would like to hear your favorites for rust prevention before dunking it and flushing and washing solutions for after.
I had seen what the saltwater does to bolts in a short period of time, I've got to slow the damage.
Thanks
 

fhhuber

Lieutenant
Joined
Jun 19, 2014
Messages
1,365
Ensure the zinc is installed and in decent shape. It helps reduce saltwater corrosion by galvanic effect. The zinc will corrode and (in theory) copper will plate out from the seawater onto the engine. (that corrodes right off giving the thin greenish tint to the aluminum corrosion layer)

Zinc and thorough flushing with fresh water is about all you can do for the internal water passages. Maintaining the paint finish on the rest of the drive is also important.
 

Melbournite

Cadet
Joined
Oct 4, 2015
Messages
20
You can always try some "salt away" additive in the flush to help dissolve the salt inside the water passages.
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Besides the flushing and rinsing with freshwater, I spray the tilt, trim, motor, pump and rams with a light coating of white lithium grease....sets up good, stays on a long time and keeps the salt away from these vulnerable areas....
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
I can launch up river and flush on the way back. I hose off the motor along with the boat and trailer

Is that a fresh or salt water river ? if fresh nothing to worry about as opposed to salt waters uses. Usually squirt a small W-40 dosis on a small brush and paint powerhead throughout with a light coat. Flushing and rinsing entire OB with fresh water is a must do if wanting Long Live the OB.

Happy Boating
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Gee, with the light salt use and the age of the motors, salt is not what will get them. Keep them greased and the gearcase full and baby them. That is all you should need.
 

gm280

Supreme Mariner
Joined
Jun 26, 2011
Messages
14,585
I would try to get it fresh water washed before any of the salt water had a chance to dry. It is a lot easier to flush out salt water then to try and dissolve dried salt back out again. JMHO!
 

relics hunter

Petty Officer 2nd Class
Joined
Jun 11, 2010
Messages
118
Some of the rivers I can launch from are fresh enough to not taste salty. Sounds like a thin oil or lithium grease will be sufficient to protect and lots of rinsing. After opening up the 6hp that I've been using for about 1 1/2 years in salt water and seeing all the build up I wonder what more I can do then to flush it after every trip. I had to give up on my first 35hp, it was a 1980 and had to much salt damage from previous owners. After too many broken bolts I couldn't convince myself to keep working on it. Now it's just a parts motor, sadly it ran but you couldn't do what was needed to maintain it.
 

gm280

Supreme Mariner
Joined
Jun 26, 2011
Messages
14,585
Some of the rivers I can launch from are fresh enough to not taste salty. Sounds like a thin oil or lithium grease will be sufficient to protect and lots of rinsing. After opening up the 6hp that I've been using for about 1 1/2 years in salt water and seeing all the build up I wonder what more I can do then to flush it after every trip. I had to give up on my first 35hp, it was a 1980 and had to much salt damage from previous owners. After too many broken bolts I couldn't convince myself to keep working on it. Now it's just a parts motor, sadly it ran but you couldn't do what was needed to maintain it.

relics hunter (interesting handle), The problem with salt water is not so much the washing everything out from the internal areas. It is the little things that the salt gets into that you never really think about. Pivot joints, bearings and seals, Things on the engine that never touches the water but is in that salty atmosphere. So basically everything gets a coat of salt just being around salt water. Water by itself is the one of world's most corrosive liquid, And that is because of the amounts on this planet and of course rain. But add salt to it and it becomes even worst. Everything rots and decays from water infiltration. Salt just makes it rot and decay quicker. :eek:
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
That's why don't like to buy second hand used OB's run in salt water as 99.99% of owners, at least down here, doesn't flush nor rinse their OB's on their entire life, stupidly assume that being an OB should resist salt water as well...

Happy Boating
 

fishin98

Chief Petty Officer
Joined
Nov 28, 2009
Messages
521
Just do a normal flush afterwards, thoroughly wash the exterior of the motor, especially the lower leg and mounting bracket. Right now I'm working on a 1999 Merc 15 hp 2str long shaft that was on a sailboat, I have the internals cleaned and flushed and have cleaned the lower parts of all the corrosion, ready to be painted when the warmer weather comes. +1 on fresh zincs.
 
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