Change of cooling fluid on Yanmar4JH4 TE

[fourgeau]

I am at a loss to identify the drain valve(s) to change the cooling fluid on this engine installed on my Beneteau 473.
Yanmar recommend changing the fluid every 500H. i have not yet obtained a service manual and would like to change the fkuid which is low ASAP

[Idiens]

Mine has some fairly obvious taps with clear plastic hoses attached mounted towards the lower rear of the engine block. The more obvious one is above the starter motor.