Rydlyme for Yanmar cooling systems
Rydlyme is the preferred choice for Yanmar cooling systems.
Too strong an acid will eat the exchanger and you'll find yourself with an expensive part to buy.
The heat exchangers found on Perkins,Universal and Westerbekes are much more durable.
However more care is needed on Yanmar Heat Exchangers
I prefer to dissasemble the heat exchanger.
Physically remove all blockage then soak in Rydlyme.
Works every time