my remote fill is in the lazzertte under the seat in the cockpit.

[Prozac]

Confused new owner of not so new 1987 Hunter 28.5. Please help! I do not understand the closed cooling system for the Yanmar 16hp. There is a remote fill line in the starboard hatch in the cockpit. It is full of antifreeze all the way to the cap. my questions:
1. Should it be that full? Concerned it will expand with motor running.
2. Is this the only coolant fill for the engine?
3. Should the freshwater tank be full? I ask because it looks like there is a heat exchange between the engine and the hot water heater.
Thanks for any advice to this novice!

 

[jdrutten]

Welcome to the forum!

I'm assuming from your description that you have a Yanmar 2GM20F which uses seawater to cool your engine coolant (so-called "freshwater") using a heat exchanger attached on the engine. The fill cap is on the heat exchanger at the engine. Connected to the fill cap on the engine is a hose that runs to a remote expansion tank which should have an upper and lower level marked on the tank. The coolant level should be between the marks on the tank when the engine is cold. It definitely should not be full all the way to the top of the tank. You should dump a little out when the engine is cold so that the remote tank is half full. If the remote tank is empty, you should add coolant at the heat exchanger, otherwise you can just top it off at the remote tank.

It also sounds like you have an external heat exchanger to warm your potable/house freshwater in a hot water heater using the hot engine "freshwater"/coolant. You wouldn't need to have water in your hot water heater, but it definitely won't hurt.

 

[Prozac]

Welcome to the forum!

I'm assuming from your description that you have a Yanmar 2GM20F which uses seawater to cool your engine coolant (so-called "freshwater") using a heat exchanger attached on the engine. The fill cap is on the heat exchanger at the engine. Connected to the fill cap on the engine is a hose that runs to a remote expansion tank which should have an upper and lower level marked on the tank. The coolant level should be between the marks on the tank when the engine is cold. It definitely should not be full all the way to the top of the tank. You should dump a little out when the engine is cold so that the remote tank is half full. If the remote tank is empty, you should add coolant at the heat exchanger, otherwise you can just top it off at the remote tank.

It also sounds like you have an external heat exchanger to warm your potable/house freshwater in a hot water heater using the hot engine "freshwater"/coolant. You wouldn't need to have water in your hot water heater, but it definitely won't hurt.

View attachment 225272
View attachment 225273

That helps a lot. Thank you for the quick and helpful response.

 

[Ralph Johnstone]

@jdrutten has almost written out the Yanmar maintenance manual for you but you would still be well advised to search the downloads on this site for the original Yanmar maintenance manual. There is waaaaaaaaaaaay more to operating this marine engine than just the water levels.

 

[jdrutten]

@jdrutten has almost written out the Yanmar maintenance manual for you but you would still be well advised to search the downloads on this site for the original Yanmar maintenance manual. There is waaaaaaaaaaaay more to operating this marine engine than just the water levels.

I love that ol' manual. You can unlock the mysteries of the universe in that manual.

 

[dlochner]

I love that ol' manual. You can unlock the mysteries of the universe in that manual.

Really? Sign me up I've been wondering about them! My search is over.

If you have shore power, it is best to keep the HW tank full. An accidental flip of a breaker will cause the heating element to be energized and moments late to burn out if the tank is empty. Heating elements for marine HW tanks are not inexpensive. After winterizing my water system and draining the tank I tape the circuit breaker in the off position to prevent it from being accidentally turn on.