Changing coolant

[Ralph Johnstone]

Gordon,I have been to hell and back when it comes to changing the coolant on my 1998 Yanmar 2GM20F.The engine is attached to a hot water heater (at a lineal distance of 8 feet) and I take meticulous care to blow out all of the old coolant out of the supply and return hoses to the heat exchanger when draining the coolant.Next comes the 50-50 mix of distilled water and antifreeze ........... and the air turns purple with cursing. Firstly I cannot get the full amount of coolant back in because of air pockets. Next, when I start the engine and idle it, I can feel that the hot coolant is not circulating and eventually I get a hight temperature alarm. Shut down the engine. Some cursing and swearing. I remove the rad cap on the coolant reservoir and it is down slightly. Add a little more coolant until it overflows. Squeeze and knead every hose I can find, burp a few bubbles and add a few more drops of coolant. Start the engine ...... high temp. alarm sounds along with more cursing and swearing. Repeat the process ......... lots more cursing and swearing ........ and so it goes for at least a dozen tries before all of the air is gone. Once the air is gone, the engine temp. does not vary five degrees at any load. Perfect cooling control.I have added the coolant quickly, I have added the coolant slowly dropwise over a period of 15 minutes ........... no improvement. I have even left the hot water tank heater hoses full but no improvement.I need your help badly as I change the coolant religiously every winter and have been kicked out of three marinas so far and suspect vigilantes in this one. Things look poorly.Regards,s/v Island Hunter

 

[Gene Barton s/v Paradigm]

Removing air

Ralph, there was an earlier post that described a technique that sounded like it made sense. Maybe it will work for you. Scroll down in this forum and look for a posting on 7/29 titled "Yanmar 2GM20F", and see if the replies are any help to you.

 

[Gordon Torresen]

Air lines

It is a well documented fact that when trying to mix air and water, the air always goes to the top. The solution to getting the air out of the system is to fill it from the top. If the hose to your water heater is above the engine, disconnect the highest one and pour your antifreeze mix in at that point. Many boaters find the highest point in there system and install a T with a valve that they can open and add the mix. Don't forget to leave room for the air to escape through the same hole.  To give you something else to swear about, you don't have a hot water heater. Once the water is hot, it doesn't do anything. It is a water heater!