Yanmar 3YM30 coolant change

[Jerry21707]

Recently purchase a 2007 Hunter 31. Not sure how old the coolant is. Would like to replace the coolant with fresh for winter layup. My Yanmar operator's manual shows 2 drain locations for the fresh water system. One on the side with the fuel pump and oil filter that looks like a plug screwed into the block and one on the port side on the hose that comes from the fresh water pump that has a slot on the bottom that I expect is a threaded plug. Are there any other drains I need to open to drain the coolant out of the fresh water cooling system. I would also empty and clean the plastic overflow tank. Any tips to keep from making a mess of it.

 

[navigator97]

I don't have a YM Series Yanmar, but the Yanmar2GM20F Freshwater (Antifreeze & Water Mix) engine. I have 2 drains with vinyl tubes attached. One is on the Starboard side of the engine - I think that connects to the Heat Exchanger, and one on the Port side. I 1st open the "Radiator" cap on the top front of the engine to vent air into the system. I lead the vinyl tube from the Starboard side (drains upper part 1st) out and into a gallon jug. After that drains I lead the other vinyl tube out to the gallon jug and drain the lower portion. Lastly I disconnect the overflow bottle/jar and pour that into the gallon jug. Next make sure all drain valves are shut tight. Lastly I fill the collant system thru to removed coolant cap on the top. The coolant that I now use, as recommended bY Yanmar dealeolrs, is Shell Rotella ELC. ELC stands for Extended Life Coolant. It comes in 50/50 Mix or in Concentrate. I get the Concentrate and mix it 50/50 with Distilled Water. Close the Collant cap and run the engine for a while to crculate coolant, then stop engine, and when cool enough, check level of coolant. Check your manual for the amount of coolant it uses. It is really a pretty straight forward process.