2001 Polaris Sportsman 400-500 DUSE and H.O. Service Manual, Page 75Get this manual
COOLING SYSTEM
WARNING: Never remove radiator cap when engine is warm or hotThe cooling system is under pressure and serious burns may resultAllow the engine and cooling system to cool before servicingFLOW Radiator
System Pressure Test
1Remove front cover2Remove recovery bottle hose from coolant filler3Connect Mity Vac (PN 2870975) to radiator and pressurize system to 10 PSIThe system must retain 10 lbs of pressure for five minutes or longerIf pressure loss is evident within five minutes, check radiator, all cooling system hoses and clamps, or water pump seal