10162980 Mariner OWNERS GUIDE

Probable Causes
Diagnostic codes
Coolant temperature gauge
Coolant level
Radiator fins
Radiator cap and/or pressure relief valve
Restriction in the coolant system
Water temperature regulator
Engine cooling fan
Quality of coolant
Coolant pump
Cylinder head gasketRecommended Actions
Diagnostic Codes
Use one of the following methods to check for diagnostic codes that relate to the temperature in the cooling system:
The electronic service tool
The display on the control panelElectronic Service Tool
Connect the electronic service tool to the diagnostic connector.
Check for active diagnostic codes on the electronic service tool.
Investigate any active codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code". Display on the Control PanelNote: The following procedure is only applicable if the application is equipped with a display on the control panel.
Check the display on the control panel for active diagnostic codes.
Troubleshoot any active codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code". Coolant Temperature Gauge
Compare the reading for the coolant temperature on the electronic service tool to the reading for the coolant temperature on a calibrated test gauge.Coolant Level
Inspect the coolant level. If necessary, add coolant.
Check the cooling system for leaks. Repair any leaks. Radiator Fins
Check the radiator fins for dirt, debris, and/or damage. Remove any dirt and/or debris and straighten any bent fins.Radiator Cap and/or Pressure Relief Valve
Pressure-test the cooling system. Refer to Systems Operation, Testing, and Adjusting, "Cooling System" for the correct procedure.
Check that the seating surfaces of the pressure relief valve and the radiator cap are clean and undamaged.
Check operation of the pressure relief valve and/or the radiator cap. If necessary, clean the components and/or replace the components. Restriction in the Coolant System
Visually inspect the cooling system for collapsed hoses and/or other restrictions.
Clean the radiator and flush the radiator. Refer to Systems Operation, Testing, and Adjusting, "Cooling System". Water Temperature Regulator
Check the water temperature regulator for correct operation. Refer to Systems Operation, Testing, and Adjusting, "Cooling System" for the proper procedure. If necessary, replace the water temperature regulator. Refer to Disassembly and Assembly, "Water Temperature Regulator - Remove and Install" for more information.Engine Cooling Fan
Make sure that the engine cooling fan is correctly installed.
Make sure that the engine cooling fan is being driven correctly by the drive belt. If necessary, adjust the belt tension or replace the drive belt. Refer to Disassembly and Assembly, "Alternator Belt - Remove and Install".
Check the engine cooling fan for damage. If necessary, replace the fan. Refer to Disassembly and Assembly, "Fan - Remove and Install". Quality of Coolant
Check the quality of the coolant. Refer to the Operation and Maintenance Manual, "Refill Capacities and Recommendations - Coolant".Coolant Pump
Inspect the impeller of the coolant pump for damage and/or erosion.
Make sure that the drive pulley is not loose on the drive shaft of the coolant pump.
If necessary, replace the coolant pump. Refer to Disassembly and Assembly, "Water Pump - Remove" and Disassembly and Assembly, "Water Pump - Install". Cylinder Head Gasket
Switch off the engine and allow the engine to cool to below normal working temperature. Remove the pressure cap for the coolant system. Start the engine and inspect the coolant for the presence of bubbles. If bubbles are present in the coolant, combustion gases may be entering the cooling system. Check the cylinder head gasket. Refer to the recommended action for the cylinder head gasket within Troubleshooting, "Oil Contains Coolant". Check the cylinder head for flatness. Refer to the recommended action for checking flatness of the cylinder head within Systems Operation, Testing, and Adjusting, "Cylinder Head - Inspect". Fit the pressure cap if there are no bubbles in the coolant.