Volvo Penta Thermostat.
Your thermostat is an intergral part of the cooling system and should be checked regularly for correct operation. Coolant should be changed, preferably with ready mixed, every 2 years and the the heat exchanger removed for cleaning every 5 years.
Volvo Penta Part No: 861911
For Volvo Penta Diesel Engines: MD2010, MD2010B, MD2010C, MD2010D, MD2010A, MD2020, MD2020A, MD2020B, MD2020C, MD2020D