Suzuki 8-25HP outboard motors Service Manual, Page 35Get this manual
SERVICE MANUAL COOLING SYSTEM
WATER PUMPA rubber impellertype water pump is mounted between the drive shaft housing and gearcaseKey (7 -FigSZlO-9) in the drive shaft is used to turn the impeller (6)If cooling system malfunction is encountered, check water intakes for plugging or partial restrictionIf water intakes are clear, remove gearcase as outlined in LOWER UNIT section and check condition of water pump, water passages and sealing surfacesWhen water pump is disassembled, inspEd impeller (6) and plate (8) for excessive wear or other damageTurn drive shaft clockwise (viewed from top) while placing pump housing (5) over impellerAvoid turning drive shaft in opposite direction after water pump is reassembledTHERMOSTATA thermostat is used to regulate operating temperatureTest thermostat by submersing in heated water with suitable thermometerThermostat should start to open at 48 -52 (118-126 F)Thermostat can be removed for inspection or renewal after removing thermostat cover located in cylinder headENGINE TEMPERATURE SENSOREngine temperature sensor is located at lower side of engine blockSensor is normally open and changes to closed circuit when engine temperature reaches 36-44 (97-111 F)When sensor is open, ignition timing is automatically advanced which increases idle speed and allows engine to warm-up quickerWhen sensor closes, ignition timing and idle speed return to normal idle settingWATERFLOW SENSORWaterflow sensor is located in cylinder head coverWater flow sensor is designed to warn operator should cooling water flow to engine become insufficientTo test sensor, remove sensor from cylinder head cover and make sure sensor float moves freelyIf not, remove pin securing float and carefully clean float and pin with waterNote that one side of pin hole in sensor is smaller than other sideDrive pin out toward larger holeConnect suitable ohmmeter between sensor wires and move float up and downOhmmeter reading should be zero ohm with float in down position and infinity with float in up position