1985-1995 Polaris ATV and Light Utility Hauler Service Manual, Page 340Get this manual
ENGINES Stroke Troubleshooting
Magnum Cooling System Troubleshooting Overheating
Insufficientwrong type coolant Air in system Thermostat stuck closed or not opening completely Radiator cap faulty (fails to pressurize) Restricted system (mud or debris in radiator fins or restriction to air flow, passages blocked in radiator, lines, pump, or water jacket) Water pump inoperative Fan motor inoperative Thermostat stuck open Faulty water pump mechanical seal (coolant leak) Faulty pump shaft oil seal (oil leak)