Snow Hawk 600HO, Set-Up, Service And Shop Manual, Page: 62 / 207

COOLING SYSTEM 6 - 4
Pressure Cap (No. 2):
o
Check if the cap pressurizes the system. If not,
install a new 90 kPa (13 PSI) cap (do not exceed this
pressure).
Thermostat:
To check the thermostat, put it in a basin of water and gradually
heat it. The thermostat should start to open when water
temperature nears 42°C (108°F). It will be almost fully open at
50°C (122°F).
The thermostat is a double action type:
(1)
Its function is to give faster warm up of the engine by
controlling a circuit; water pump — engine — coolant
tank. This is done by bypassing the heat exchanger
radiator circuit and using what it called a short circuit
during warm up, i.e. before the coolant temperature
reaches 42°C (108°F).
(2)
When the liquid is warmed enough, the thermostat
progressively opens the circuit; water pump
— engine — heat exchangers — coolant tank to keep
the liquid at the desired temperature. (See the
diagram of the exploded view on page 6-1).
These 2 functions have the advantage of preventing
a massive entry of cold water into the engine.