1985 Ski-Doo snowmobile Service Manual, Page 191Get this manual
Sub-section 09
Section 02 ENGINE (537 ENGINE TYPE)
INSPECTION
Check general condition of hoses and clamp tightness
16, Thermostat
To check thermostat, put it in water and heat the water Thermostat should open when water temperature reaches 42 1107.6 FlThiS thermostat IS "double action type" A- Its function IS to give faster warm up of the engine by provoking circuit; water pumpenginereservOirThis is done by closing the heat exchanger cirCUIt
DRAINING THE SYSTEM
WARNING: Never drain or refill the cooling system when engine is hot
To drain the cooling system, siphon the coolant mixture from the coolant tank, using primer pump and length of plastic hose and steel tubing inserted as deep as possible Into the lower hose of the tank
Coolant tank
PfirTler pLJrn()
4.54 liters 160 Imp ounres 154 US ounces
AQ15002010