Being new to engine maintainence (this is my first winter as an owner), I'm trying to do all the right things during my haul out projects. I've read that checking engine zincs is an important but often neglected task. Although I've found the page on engine zincs in my Yanmar manual, it only shows locations on the raw water cooled model. I suspect (but certainly want to verify with those more knowledgable) that the fresh water cooled model (2GM20F) doesn't have zincs because there is no actual saltwater inside the engine. Can anyone either confirm this or steer me towards the locations of the zincs in my model? Thanks, Martin Cole s/v Ares
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Frequently asked question.
Martin: This subject comes up regularly. You are correct in your assumption. No zincs on fresh water cooled engines.
Martin: This subject comes up regularly. You are correct in your assumption. No zincs on fresh water cooled engines.
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Marc Honey
How about on prop or prop shaft?
Been on fresh water for years, but if boat is moved to salt, wouldn't it need a zinc on shaft or prop nut?
Been on fresh water for years, but if boat is moved to salt, wouldn't it need a zinc on shaft or prop nut?
Yes, but that is a seperate issue.
Marc: You should have a zinc on the prop shaft. This is a seperate issue but also should be addressed. My understanding is there is less stray electrical current in fresh water than salt, but it can occur. I have had my boat in fresh and brackish water since it was new and have alway had a zinc on the shaft.
Marc: You should have a zinc on the prop shaft. This is a seperate issue but also should be addressed. My understanding is there is less stray electrical current in fresh water than salt, but it can occur. I have had my boat in fresh and brackish water since it was new and have alway had a zinc on the shaft.
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Bob greenfield
Zincs
Steve, keeping boat in water next 2 years. Where would I attached a sacraficial zinc so that it prevents pitting of the prop while docked? I have a 29.5, 1994 Hunter.
Steve, keeping boat in water next 2 years. Where would I attached a sacraficial zinc so that it prevents pitting of the prop while docked? I have a 29.5, 1994 Hunter.
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Ben
shaft
Bob attach the zinc to the shaft. Steve your understanding is incorrect, no need for zincs in fresh water.
Bob attach the zinc to the shaft. Steve your understanding is incorrect, no need for zincs in fresh water.
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Craig
whats the difference? raw water/fresh water
we have a hose that brings in water thru the bottom and circulates thru the engine and out. i think its called the raw water intake. i am not all that well in tune with this but does this mean raw water? then whats fresh water? thanks. i would say we do not have a closed system?
we have a hose that brings in water thru the bottom and circulates thru the engine and out. i think its called the raw water intake. i am not all that well in tune with this but does this mean raw water? then whats fresh water? thanks. i would say we do not have a closed system?
2GM20F or 3GM30F
Craig: Yanmar made 2 versions of these engines. What they consider a Fresh Water Version has a expansion tank that allows you to add ANTI-FREEZE. This is what circulates throughout the engine not the RAW WATER that is sucked in from the body of water that we hope you are floating in. Now taking into account that you are sailing in fresh water, this does not make a lot of difference except the fact that the temperature of the engine is much easier to control with a fresh water cooled version. They recirculate the antifreeze solution through the engine and have a thermostat to regulate the temperature of the coolant. If you have a raw water cooled engine the raw water is picked up, circulated through the engine and exhausted out the mixing elbow with the exhaust..... These engines typically run cooler so and they do not run as efficently as a fresh water cooled engine. The difference for someone that sails in salt water is the fact that they have salt water inside the cooling jacket of the engine. This can corrode the engine and deposit salt that plugs up the water passages. Does this make any sense?
Craig: Yanmar made 2 versions of these engines. What they consider a Fresh Water Version has a expansion tank that allows you to add ANTI-FREEZE. This is what circulates throughout the engine not the RAW WATER that is sucked in from the body of water that we hope you are floating in. Now taking into account that you are sailing in fresh water, this does not make a lot of difference except the fact that the temperature of the engine is much easier to control with a fresh water cooled version. They recirculate the antifreeze solution through the engine and have a thermostat to regulate the temperature of the coolant. If you have a raw water cooled engine the raw water is picked up, circulated through the engine and exhausted out the mixing elbow with the exhaust..... These engines typically run cooler so and they do not run as efficently as a fresh water cooled engine. The difference for someone that sails in salt water is the fact that they have salt water inside the cooling jacket of the engine. This can corrode the engine and deposit salt that plugs up the water passages. Does this make any sense?
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Craig
for steve
iwould guess then that i have a raw water cooled system as we have a raw water pickup from the lake water that circulates thrue and out the exhaust in back the boat. we have an impellor in the system and i always look for the water coming out the back. number one is this statement sound correct and then is a fresh water system with the expansion tank, does that not deal with the raw water and the water out the exhaust as it is constantly circulating within and not exiting the boat? i have antifreeze but dont think i would call that an expansion tank. thanks for the help. craig ps if i am raw water would that mean i have the three zincs it talks about in my yanmar owners manual.
iwould guess then that i have a raw water cooled system as we have a raw water pickup from the lake water that circulates thrue and out the exhaust in back the boat. we have an impellor in the system and i always look for the water coming out the back. number one is this statement sound correct and then is a fresh water system with the expansion tank, does that not deal with the raw water and the water out the exhaust as it is constantly circulating within and not exiting the boat? i have antifreeze but dont think i would call that an expansion tank. thanks for the help. craig ps if i am raw water would that mean i have the three zincs it talks about in my yanmar owners manual.
Ben: Not on my boat.
Ben: You may want to go without zincs on your boat but not me. You are correct that pure fresh water is not a good electrolyte, but it is an electrolyte none the less. Fresh water is an electrolyte - a poor one. Salt water is a strong one - the warmer the stronger. Polluted water, contaminated water and acid water can be strong electrolytes. So if you decide to go without zincs you are taking your chances. When a zinc costs $7 why would you not have one?
Ben: You may want to go without zincs on your boat but not me. You are correct that pure fresh water is not a good electrolyte, but it is an electrolyte none the less. Fresh water is an electrolyte - a poor one. Salt water is a strong one - the warmer the stronger. Polluted water, contaminated water and acid water can be strong electrolytes. So if you decide to go without zincs you are taking your chances. When a zinc costs $7 why would you not have one?
Craig, it is fresh water cooled.
Craig: You do have a FRESH water cooled engine if the engine contains antifreeze. This is what they are referring to. The raw water (be it fresh or salt) is run through a heat exchanger (it sits on the top of your engine). The fresh water (antifreeze mixture) runs through this same exchanger. The exchanger is a container with two sets of tubes (fresh & raw water). As the fresh water runs through the exchanger the heat is carried off by the raw water which lowers the temperature of the coolant. The raw water is exhausted out the mixing elbow with the cylinder gases that where created by the combustion in the engine. Being in fresh water this is not nearly as clear as someone that has a boat in the ocean. When you have a boat that lives in salt water and bring it to the fresh water environment you can also have some other problems from the salt deposits that may crystalize and then they swell causing a blockage in the passageways. This is not nearly as common with a FRESH water cooled engine, but can be a real problem with a RAW water cooled engine where the saltwater actually passes in the water jacket within the engine.
Craig: You do have a FRESH water cooled engine if the engine contains antifreeze. This is what they are referring to. The raw water (be it fresh or salt) is run through a heat exchanger (it sits on the top of your engine). The fresh water (antifreeze mixture) runs through this same exchanger. The exchanger is a container with two sets of tubes (fresh & raw water). As the fresh water runs through the exchanger the heat is carried off by the raw water which lowers the temperature of the coolant. The raw water is exhausted out the mixing elbow with the cylinder gases that where created by the combustion in the engine. Being in fresh water this is not nearly as clear as someone that has a boat in the ocean. When you have a boat that lives in salt water and bring it to the fresh water environment you can also have some other problems from the salt deposits that may crystalize and then they swell causing a blockage in the passageways. This is not nearly as common with a FRESH water cooled engine, but can be a real problem with a RAW water cooled engine where the saltwater actually passes in the water jacket within the engine.
Mis-stated.
Craig: Actually the freshwater (antifreeze) does not run thru the tubes but surrounds that tubes that the raw water runs through. This is actually a water cooled radiator. The raw water runs thru the tubes and removes the heat from the engine cooling water.
Craig: Actually the freshwater (antifreeze) does not run thru the tubes but surrounds that tubes that the raw water runs through. This is actually a water cooled radiator. The raw water runs thru the tubes and removes the heat from the engine cooling water.
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