Instruction Book for Bolinder Single & Twin-cylinder Engines Return to Instruction Book Cooling System   The engine is water cooled, the coolant being circulated by a special pump mounted on the timing gear casing on the left-hand side of the engine and driven from the camshaft. The pump draws in seawater through the bottom valve and feeds it into the cooling jacket around the exhaust manifold. From here the water is led through the cylinder block where it first cools the cylinder liners and then passes through passages up into the cylinder head. Here it is sprayed out to provide concentrated cooling of the exhaust passages and the nozzles. The heated coolant passes via the thermostat to the discharge. As long as the coolant is cold, the thermostat is closed for supply to the engine; the greater part proceeding direct to the discharge. This causes the water in the engine to rapidly heat up to 160deg F ( 70deg C ). At this temperature the thermostat begins to open and is fully open by the time temperature has reached 175deg F ( 80deg C ), permitting maximum supply of water to the engine. The thermostat thus operates to maintain the coolant at 160-175deg F ( 70-80deg C ), the best temperature for the engine. Running at too low temperature causes poor combustion and abnormal cylinder wear.       1  Coolant pipe line between exhaust manifold and engine block     2  Discharge pipe line     3  Thermostat housing     4  Water pump