Pinpoint Test A: Loss of Coolant
Engine Cooling
Pinpoint Test A: Loss of Coolant
Normal Operation
The engine cooling system is a closed system providing for coolant expansion and contraction and also changes in pressure as coolant warms and cools with engine operation. Various gaskets, seals, hoses and clamps contain coolant within the cooling system and keep other fluids and contaminants from entering the cooling system.
Coolant loss can be attributed to either external or internal leaks anywhere within the cooling system.
For engine specific information, refer to Engine Cooling Description and Operation in the Description and Operation.
This pinpoint test is intended to diagnose the following:
- Coolant hoses or tubes
- Hose clamps
- Coolant pump O-ring seal
- Thermostat housing gasket
- Thermostat housing
- Radiator
- Pressure relief cap
- Coolant pump leaking from weep hole
- Heater core
- Engine gaskets
- Coolant expansion tank
- Cylinder block core plugs
- Cylinder head core plugs
- Block heater (if equipped)
PINPOINT TEST A: LOSS OF COOLANT
WARNING: Always allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.
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A1 CARRY OUT INSPECTION AND VERIFICATION
- Carry out the Inspection and Verification procedure. Inspection and Verification
- Were any concerns found?
Yes
REPAIR as needed. TEST the system for normal operation.
No
GO to A2.
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A2 CHECK THE ENGINE COOLANT LEVEL
NOTE: Allow the engine to cool before checking the engine coolant level.
- Ignition OFF.
- Visually inspect the engine coolant level at the coolant expansion tank.
- Is the engine coolant level within specifications?
Yes
GO to A3.
No
ADJUST the engine coolant level as necessary. GO to A3.
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A3 PRESSURE TEST THE ENGINE COOLING SYSTEM
- Pressure test the engine cooling system. Refer to Component Tests, Cooling System Pressure Test. Component Tests and General Diagnostics
- Does the engine cooling system leak?
Yes
REPAIR or INSTALL new components. TEST the system for normal operation.
No
GO to A4.
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A4 CHECK THE PRESSURE RELIEF CAP
- Carry out the pressure relief cap pressure test. Refer to Component Test, Pressure Relief Cap Pressure Test. Component Tests and General Diagnostics
- Is the pressure relief cap OK?
Yes
GO to A5.
No
INSTALL a new pressure relief cap. TEST the system for normal operation.
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A5 CHECK THE ENGINE COOLANT FOR AN INTERNAL LEAK
- Inspect the engine coolant in the coolant expansion tank for signs of engine oil.
- Is engine oil evident in the coolant?
Yes
GO to Engine System - General Information Testing and Inspection for engine diagnosis.
No
GO to A6.
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A6 CHECK THE ENGINE OIL FOR COOLANT
- Remove the oil level indicator from the engine.
- Is coolant evident in the oil?
Yes
GO to Engine System - General Information Testing and Inspection for engine diagnosis.
No
GO to A7.
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A7 CHECK THE COOLING SYSTEM FOR COMBUSTION GASES
- NOTE: Use UView(R) Combustion Leak Tester part number UVU560000-R or equivalent.
- Using a cooling system combustion gas leak tester, following the instructions supplied with the tester, check the coolant for combustion gases.
- Are combustion gases present?
Yes
GO to Engine System - General Information Testing and Inspection for engine diagnosis.
No
The cooling system is operational.
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