Colleagues, Slowly I’m losing glycol coolant from the expansion container on top of my Yanmar 3GM30F. In a season the container will go nearly empty. Since the coolant is intensely green I would have noticed a external leak in the engine compartment. The engine is running fine and very little smoke is appearing in the exhausts. When I checked the dipstick the other day (cool motor) the oil appeared OK. Cause for worry? Can normal evaporation explain this? Anyone have the same experience?
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R. Young
Two ideas
Its normal for the expansion tank to change water positions, may be possible that your seeing a normal variation - unless you have noticed it is a continual loss over the season. If thats the case then its leaking out somewhere. If its at the heat exchanger then the leak is mixing with the sea coolant and going out the stern where you will never notice it. Im guessing, but I think the manual may have some pressure testing procedure. Roger Destiny - Hunter 37
Its normal for the expansion tank to change water positions, may be possible that your seeing a normal variation - unless you have noticed it is a continual loss over the season. If thats the case then its leaking out somewhere. If its at the heat exchanger then the leak is mixing with the sea coolant and going out the stern where you will never notice it. Im guessing, but I think the manual may have some pressure testing procedure. Roger Destiny - Hunter 37
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Miles
Check the water heater?
The coolant runs from the engine to the hot water heater, you might have a small leak at the connection to the water heater or (unlikely) within the heater itself. From your description it sounds like a pretty slow leak, maybe a hose clamp just needs to be tightened. The fluid level will vary a bit with temperature but it won't dissapear unless there's a leak somewhere.
The coolant runs from the engine to the hot water heater, you might have a small leak at the connection to the water heater or (unlikely) within the heater itself. From your description it sounds like a pretty slow leak, maybe a hose clamp just needs to be tightened. The fluid level will vary a bit with temperature but it won't dissapear unless there's a leak somewhere.
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Scott
Same thing
I am experiencing the same slow loss of coolant on our 356 except that we've switched to the pink stuff as Yanmar recommends. I have no idea where it is going.
I am experiencing the same slow loss of coolant on our 356 except that we've switched to the pink stuff as Yanmar recommends. I have no idea where it is going.
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R. Young
Pink Stuff???
Did you say you replaced the glycol solution with the pink stuff (i.e., the stuff we all use to winterize the external exchanger component - That does not sound right. You got that from Yanmar? Please elaborate. R. Young Destiny - Hunter 37
Did you say you replaced the glycol solution with the pink stuff (i.e., the stuff we all use to winterize the external exchanger component - That does not sound right. You got that from Yanmar? Please elaborate. R. Young Destiny - Hunter 37
Havoline Extended Life.
Yanmar recommeds that you use the Extended Life Havoline antifreeze. This is NOT the stuff you use in your fresh water system.
Yanmar recommeds that you use the Extended Life Havoline antifreeze. This is NOT the stuff you use in your fresh water system.
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Mark Personne
Yanmars response
Thank you all for your input. I also checked with Yanmar this morning. A leakage of coolant, even slow, is a cause for investigation. Three alternatives are possible 1. Into the boat (visible), 2. Into the motor (motor oil is discolored) 3. Into seawater system (coolant goes away with exhausts, but seawater might leak in the other direction). I was recommended to have a mechanic doing a test-pressurizing of the system. A warranty issue since the problem has been there from the start.
Thank you all for your input. I also checked with Yanmar this morning. A leakage of coolant, even slow, is a cause for investigation. Three alternatives are possible 1. Into the boat (visible), 2. Into the motor (motor oil is discolored) 3. Into seawater system (coolant goes away with exhausts, but seawater might leak in the other direction). I was recommended to have a mechanic doing a test-pressurizing of the system. A warranty issue since the problem has been there from the start.
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Carol
Had the same problem
We were leaking coolant as well on our 380 and it turned out to be a leaky cap on the radiator (do you call it a raditor on a boat?) No further problems after we got that replaced.
We were leaking coolant as well on our 380 and it turned out to be a leaky cap on the radiator (do you call it a raditor on a boat?) No further problems after we got that replaced.
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Tony Wilcox
Coolant Leakage
Same problem I had on 376. Tightened all clamps on heater hose connections , result---- no more coolant loss. Tony
Same problem I had on 376. Tightened all clamps on heater hose connections , result---- no more coolant loss. Tony
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Roald Johansen
Coolant leakage
I had a similar problem when I first got the boat. I discovered a small leakage trough the center of the heatexchanger cap. The leaking coolant evaporated without leaving any marks in the engineroom. New heatexchanger cap cured the problem.
I had a similar problem when I first got the boat. I discovered a small leakage trough the center of the heatexchanger cap. The leaking coolant evaporated without leaving any marks in the engineroom. New heatexchanger cap cured the problem.
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Jeff Letteri
Add some Dish Soap
Add some dish soap to the coolant and if you have bubble in the exaust you have a leak from fresh to sea water...other then that you have a hose cap etc. leak Jeff Hull Number 4 Desinty
Add some dish soap to the coolant and if you have bubble in the exaust you have a leak from fresh to sea water...other then that you have a hose cap etc. leak Jeff Hull Number 4 Desinty
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Toni
same problem
Mark, I hope that you will post here when you find out what is wrong with your system. We checked our overflow container and noticed that it was below the low level when cold. The little fluid that was in the bottom was a muddy greenish black. We did look at each of the suggestions posted here - and tried them all. Then we called the dealer to have them take a look at it. John cleaned out the overflow container and refilled it with fresh coolant. Boat seems to be running just fine. But I'm worried that there is still something wrong because the coolant should not have been that low.
Mark, I hope that you will post here when you find out what is wrong with your system. We checked our overflow container and noticed that it was below the low level when cold. The little fluid that was in the bottom was a muddy greenish black. We did look at each of the suggestions posted here - and tried them all. Then we called the dealer to have them take a look at it. John cleaned out the overflow container and refilled it with fresh coolant. Boat seems to be running just fine. But I'm worried that there is still something wrong because the coolant should not have been that low.
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lim oursler
3gmf coolant leak suggestions for repair
I went through this a few weeks ago, replaced the gaskets at both ends of the heat exchanger, bypassed the water heater heat exchanger.. found in the end that my radiator cap collar on top of the heat exchanger, held by 4 screws, was leaking. After engine shut off, could see a slight, very slight vapor arising. Had also previously replaced radiator cap. And with leaks, it always pays to go back an look under the engine to see water running down from anywhere. Obviously you have no water in the oil
I went through this a few weeks ago, replaced the gaskets at both ends of the heat exchanger, bypassed the water heater heat exchanger.. found in the end that my radiator cap collar on top of the heat exchanger, held by 4 screws, was leaking. After engine shut off, could see a slight, very slight vapor arising. Had also previously replaced radiator cap. And with leaks, it always pays to go back an look under the engine to see water running down from anywhere. Obviously you have no water in the oil
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