Pinpoint Test A: Loss of Coolant

Engine Cooling

Pinpoint Tests

Pinpoint Test A: Loss of Coolant

Normal Operation

The engine cooling system is a closed system providing for coolant expansion and contraction as well as 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
- Thermostat O-ring seal
- Coolant pump gasket or O-ring seal
- Thermostat housing
- Radiator
- Transmission fluid cooler (in radiator)
- Pressure relief cap
- Coolant pump leaking from weep hole
- Cylinder block coolant pump hole cover
- Heater core
- Coolant crossover manifold assembly
- Engine gaskets (may leak internally or externally)
- Oil filter adapter (may leak internally or externally)
- Oil cooler (may leak internally or externally)
- Coolant expansion tank
- Degas bottle
- 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. For 3.5L GTDI, 3.7L or 5.0L engines, refer to Component Tests, Cooling System Pressure Test - Degas Bottle Systems. For 6.2L engines, refer to Component Tests, Cooling System Pressure Test - Coolant Expansion Tank Systems. 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 ENGINE COOLANT FOR AN INTERNAL LEAK

- Inspect the engine coolant in the degas bottle or the coolant expansion tank and the radiator for signs of engine oil or transmission fluid.
- Is engine oil or transmission fluid evident in the coolant?

Yes
If engine oil is evident, GO to Engine System - General Information Testing and Inspection for engine diagnosis. If transmission fluid is evident, INSTALL a new radiator. REPAIR the transmission as necessary. TEST the system for normal operation.

No
GO to A5.

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A5 CHECK THE ENGINE OIL AND TRANSMISSION FLUID FOR COOLANT

- Remove the oil level indicators from the engine and the transmission.
- Is coolant evident in the oil or transmission fluid?

Yes
If coolant is in the engine oil, GO to Engine System - General Information Testing and Inspection. If coolant is in the transmission fluid, INSTALL a new radiator. REPAIR the transmission as necessary.

No
GO to A6.

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A6 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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