Kubota WSM STV32 Workshop Manual page 70

STV32 · STV36 · STV40, WSM
2. COOLING SYSTEM
Bottom bypass system is introduced in 03-M Series
for improving the cooling performance of the radiator.
While the temperature of coolant in the engine is low,
the thermostat is held closed and the coolant is allowed
to flow through the bypass pipe and to circulate in the
engine.
When the temperature exceeds the thermostat valve
opening level, the thermostat fully opens itself to
prevent the hot coolant from flowing through the bypass
into the engine.
In this way, the radiator can increase its cooling
performance.
(1) Thermostat
1-M2
ENGINE
(A) Thermostat Closed
(B) Thermostat Open
0000006293E
KiSC issued 04, 2006 A