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How is the Current created
Ionic Conduction
The ions in the water are what allow it to conduct electricity. When these ions flow across the thermostat they initiate flowing electrons in the thermostat from the stainless to the copper and to the brass. That initiates a flow of ions through the water into the less noble Aluminum Block, this initiates electron flow on the conduction band of the aluminum until it completes the circuit back to the seawater. When the circuit does complete, electrons from the conduction band are lost to the water, and they take atoms with them.
The Galvanic Series
This is showing the galvanic series, it ranks the common metals by there tendency to corrode. You can see magnesium is very low and then Zinc, Beryllium and aluminum. You can see that zinc is more corrosive than aluminum but not by a substantial amount. This means that the OEM zinc anodes in the block are unable to effectively remove the charge from the thermostat because they are too far away which makes them high resistance.
The path of resistance to the zincs becomes higher than the aluminum because of their distance from the source, the thermostat. By placing our Thermostat Anode in contact with the thermostat we become the absolute path of let resistance for the current to complete the circuit, and thus save your engine from corroding as we do instead.
The Conduction Band
The aluminum lattice that makes up your block is composed of atoms that have inner shell electrons that stay with each atom and outer shell valence electrons that make up the conduction band of the entire lattice and they are free to roam around, as they are shared, and it is this movement that allows metals to conduct electricity. When the electrons flowing in the thermostat turn it into the cathode, the flowing ions begin to move the outer shell electrons in the aluminum and they complete the circuit becoming the anode.
In this process the electrons will begin to flow toward the ions that initiated their flow, which are in the water. This means the electrons end up leaving the surface of the aluminum into the water and when they do so, that atom becomes unstable, loses its other 2 valence electrons and then the atom falls into the water and your engine just lost mass, its a small constant but the loss is constant and it adds up over time.
How much current is created? How does it affect your motor?
Average Current
Since the current is created by the ions in the water, how fast they are flowing effects the current, it also effects the ability of the ions to conduct electricity. For this reason there is an increase current with speed and then there is a decreasing current with additional speed. You are reading a negative current because this represents electrons flowing out of the aluminum and into the water, this represents the engine dissolving by losing one atom per 3 electrons.
This is about the average current for 3500-4000 RPM and it begins to reduce around 4500 rpm and gets its lowest over 5500 RPM. When the water begins to move too fast for the ions to connect with the electrons then the galvanic circuit begins to break. This also forces the electrons that do reconnect to do so on a larger volume scale which reduces the probability of deep pits and increase the probability of a higher number of shallow pits. This is why high RPM runners can put lots of hours on their motors and seemingly get lucky with the corrosion holes, its less current spread out over more area of corrosion.
How much Mass and Volume loss is there?
It is completely RPM specific but we can use Faraday's Law of Electrolysis to determine exactly. We have observed that the common range is 0.1 milliamp to 0.4 milliamps of current, and this corresponds to the mass losses that you see in the chart. Aluminum has a mass density of 2.7 grams per cubic centimeter so we have calculated the mass loss in volume of engine material.
You can see that per 100 hours even if you were running over 5500 rpms the entire time you would have lost 1.24 cubic millimeters, and even at that rate that is enough mass loss to see a hole within a couple hundred hours but the corrosion is spread out at those rpms. at 0.4 milliamps you are losing 4.97 cubic millimeters ever 100 hours of runtime. This is the range my boat was run in most of its life and it got the hole around 650-700 hours.
Our Zinc Anode after 175 Hours Use
This was the first sleeve every made and the first degradation test. After 175 hours exposed to 0.3 milliamps it lost 0.7 grams from 14.1 to 13.4 grams and the pump died. We believe it would have continued absorbing current for another 125 hours plus until it ran out of usable surface area but we are restarting that test this week. This represents the same type of loss your engine is experiencing .
The current literally dissolves the engine one atom at a time all day every day until your engine starts to leak water either outside or into the oil. Casting error also plays a part into this, but it doesn't have to be a waiting game of hoping to get lucky anymore. ALL you have to do is install a WaterDog Outboard Savers Thermostat Anode and you never have to worry about his happening again. Its a no brainer, everyone who has seen one of these engines fail with a hole knows that..
Maintenance is not causing corrosion, it blows head gaskets
Hydrotalcite and Aragonite Buildup
This is the result of the corrosion, it goes through a process called Electrocoagulation which is a direct result of the current running through the block. Hydrotalcite is made up of Aluminum Hydroxide and Magnesium Hydroxide, The aluminum from your block and the magnesium comes from the water. They combine together in layers with Chloride or other anions packed between. This molecule is capable of breaking down in layers over time and we have developed a way to do that Called the WaterDog Power Flush where you can use a submersible pump to flow water through your engine for days on end and lots of material will come out of your water jacket.
This corroded buildup can be flushed away as you develop it, if it is not then it begins to reduce the diameter of your water jacket journals very quickly. This ends up speeding the water flow, which reduces its ability to absorb heat. This slowly thermally stresses the block over time robbing you of compression. This build up stops happening the day you install our Anode because without electricity, you can have no electrocoagulation.
Electrocoagulation is choking your engine
inside the Engines we have current flowing through the block and it allows for the Floc or byproduct of the reaction to clump up on the anode. Some also builds up on the thermostat you have seen this as a green slime, on the inside of the engine it becomes this very hard yellow substance.
The substance is made of the metal hydroxides and very hard carbonate minerals from the sea, this is why they sell very acidic cleaners for the engines they refer to as descaler's. We highly discourage their use. The reason is that anything that can break down the buildup in these engines can also break down the engines, because the buildup is made of metal. If you need to clean your engine it is because it has already corroded lots of volume out, and you are risking having a catastrophic failure if you use acidic cleaners on worn thin metal. Unfortunately these cleaners are probably responsible for some holes on their own, you can soak metal in any of the as an experiment to see for yourself what happens.
15 hours on a Suzuki 15 HP motor
This was a 15 HP Suzuki we installed an Outboard Saver On and I was shocked at this Hydrotalcite and Aragonite buildup already. Admittedly, this is a person who was not flushing well, you could see how within a couple hundred hours this engine would start running hot as this substance would be all through it if a person was not flushing well but its important to note that the corrosion takes place regardless if the flushing is happening or not.
With our Anode installed it will still dissolve producing zinc hydroxide instead of aluminum hydroxide., but it will NOT stick to the inside of the motor because there will be no current in the block to allow it to coagulate on to the walls.
Ultimately, this means that our Anode not only stops your engine from corroding, it will stop it from developing overheating problems later in life and it makes the engine live longer as a result of that as well. The reality is that our Zinc Anode turns a new engine into a family heirloom.