2008 Polaris Ranger RZR Service Manual, Page 106Get this manual
ENGINE Excessive Smoke and Carbon Buildup
Excessive piston-to-cylinder clearance Wet sumping due to over-full crankcase Worn rings, piston, or cylinder Worn valve guides or seals Restricted breather Air filter dirty or contaminated
Cooling System
Overheating
Low coolant level Air in cooling system Wrong typemix of coolant Faulty pressure cap or system leaks Restricted system (mud or debris in radiator fins causing restriction to air flow, passages blocked in radiator, lines, pump, or water jacket, accident damage) Lean mixture (vents, fuel pump or fuel valve) Fuel pump output weak Electrical malfunction Water pump failure Loose impeller Thermistor failure Cooling fan inoperative or turning too slowly (perform current draw test) Low oil level Spark plug incorrect heat range Faulty hot light circuit Thermostat stuck closed or not opening completely