Yanmar 2GM20F anti-freeze replacement

[Michel16055]

Hello, I have a 1987 Oday 302 with a Yanmar 2GM20F
2 questions.
#1-I want to replace the anti-freeze but am unable to find the drain-plug. (what type of anti-freeze to use)

#2- In the water cooling cylinder, I want to clean the calcium buildup with CLR.
Is there a particular way to remove it?

I'm a visual person so any pictures would be greatly appreciated.
thanks
Michel

 

[Bob 04 H260]

I just did this on my 3GM30F engine. I drained the coolant using the small valves on the engine.

I removed the thermostat.

Using a fresh water hose I reverse flushed the raw water cooling system going in at the back of the heat ex-changer and coming out the hose from the raw water pump. I then reverse flushed the fresh water side of the block going in at the connection for the water heater return hose and coming out at the water heater supply hose.

I then reverse flushed the heater circuit.

I did not use any chemicals to clean the engine.

I replaced the thermostat, and drained all the water.

\ added the long life coolant I bought from the Yanmar dealer, a new mixing elbow and exhaust manifold, all new rubber hoses. A Lifeseal raw water pump back, a new impeller, and a new belt.

I hope this will be good for the next few years, Bob

 

[Ralph Johnstone]

The only thing I would add to Bob's list is to use distilled water when making up the 50/50 antifreeze mix. No worries about scale buildup.

 

[Steve Dion]

The only thing I would add is to purchase 50/50 Extended Life (no mixing or guessing required).

If you change the coolant type you need to be sure that there is none of the old coolant remaining in the system.