For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
DEFINITION: The cooling system is loosing coolant either internally or externally.
1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to Symptoms - Engine Cooling
2 | Repair any present DTCs. Refer to Diagnostic Starting Point - Engine Cooling . Is the action complete? | Go to Step 3 | --
3 | Inspect the coolant level. Is the coolant at the proper level? | Go to Step 5 | Go to Step 4
4 | Fill the cooling system to the proper level. Refer to Cooling System Draining and Filling . Is the action complete? | Go to Step 5 | --
5 | If the engine is suspected to have a coolant leak into the cylinder, the coolant can hydraulically lock the cylinder. Does the engine crankshaft rotate? | Go to Step 6 | Go to Step 31
6 | Engine overheating can cause a loss of coolant. Is the engine overheating? | Go to Step 32 | Go to Step 7
7 | Extended engine operation with a low coolant level can cause engine internal component failure. Is the engine knocking? | Go to Step 34 | Go to Step 8
8 |

1. Idle the engine at normal operating temperature.
2. Inspect for heavy white smoke coming out of the exhaust pipe.

Is a heavy white smoke present from the exhaust pipe?

Go to Step 9

Go to Step 10

9 | Coolant in the exhaust system creates a distinctive, burning coolant odor in the exhaust. Condensation in the exhaust system can cause an odorless white smoke during engine warm up. Does the white smoke have a burning coolant type odor? | Go to Step 33 | Go to Step 10
10 | With the engine idling, inspect the coolant recovery system. Does the coolant recovery system discharge coolant while the engine is idling? | Go to Step 15 | Go to Step 11
11 | Visually inspect the hoses, pipes, and hose clamps at the following locations:

• | The auxiliary heater core

• | The coolant reservoir

• | The heater core

• | The radiator

Are any of the hoses, clamps, or pipes leaking?

Go to Step 24

Go to Step 12

12 | Visually inspect the following components:

• | The block heater

• | The coolant pressure cap

• | The coolant reservoir

• | The core plugs

• | The cylinder head gaskets

• | The engine block

• | The intake manifold

• | The radiator

• | The thermostat

• | The water pump

Are any of the listed components leaking?

Go to Step 24

Go to Step 13

13 |

1. Pressure test the cooling system. Refer to Cooling System Leak Testing .
2. Visually inspect the components listed in steps 11 and 12 again.

Are any leaks present?

Go to Step 24

Go to Step 14

14 | Pressure test the coolant pressure cap. Refer to Pressure Cap Testing . Does the coolant pressure cap hold pressure? | Go to Step 16 | Go to Step 25
15 | Pressure test the coolant pressure cap. Refer to Pressure Cap Testing . Does the coolant pressure cap hold pressure? | Go to Step 35 | Go to Step 25
16 | Inspect for the following conditions:

• | A coolant smell inside of the vehicle

• | Coolant in the HVAC module assembly drain tube

• | Coolant on the vehicle floor covering under the HVAC module assembly

Is coolant present?

Go to Step 26

Go to Step 17

17 | If equipped with auxiliary heating, inspect for the following conditions:

• | A coolant smell inside of the vehicle

• | Coolant in the auxiliary HVAC module assembly drain tube

• | Coolant on the floor covering near the auxiliary HVAC module assembly

Is coolant present?

Go to Step 27

Go to Step 18

18 |

1. Add 30 ml (1 oz) of Extended Life Coolant Leak Detection Dye GM P/N 89022219 (Canadian P/N 89022220) to the cooling system for each 15 liters (4 gallons) of coolant. Refer to Approximate Fluid Capacities .
2. Start the vehicle and allow the engine to reach normal operating temperature.
3. Shut the engine off.
4. Use J 42220 Universal 12V Leak Detection Lamp to visually inspect the components listed in steps 11 and 12.

Are any leaks present?

Go to Step 24

Go to Step 19

19 | Use J 42220 to inspect for the following conditions:

• | Coolant dye in the HVAC module drain tube

• | Coolant dye on the vehicle floor covering near the HVAC module

Is coolant dye present?

Go to Step 26

Go to Step 20

20 | Use J 42220 to inspect for the following conditions:

• | Coolant dye in the auxiliary HVAC module drain tube

• | Coolant dye on the vehicle floor covering near the auxiliary HVAC module

Is coolant dye present?

Go to Step 27

Go to Step 21

21 | Inspect the underside of the oil fill cap for a gray/white milky substance. Is there a milky substance under the oil fill cap? | Go to Step 22 | Go to Step 23
22 | Inspect the engine oil fluid level indicator for a gray/white milky substance. Is there a milky substance on the engine oil fluid level indicator? | Go to Step 33 | Go to Step 23
23 | Inspect the automatic transmission oil fluid level indicator, if equipped, for a gray/white milky substance. Is there a milky substance on the automatic transmission fluid level indicator? | Go to Step 28 | Go to Step 36
24 | Repair or replace the leaking component. Refer to the appropriate repair. Is the repair complete? | Go to Step 36 | --
25 | Replace the coolant pressure cap. Is the repair complete? | Go to Step 36 | --
26 | Replace the heater core. Refer to Heater Core Replacement . Is the repair complete? | Go to Step 36 | --
27 | Replace the auxiliary heater core. Refer to Auxiliary Heater Core Replacement . Is the repair complete? | Go to Step 36 | --
28 |

1. Remove the transmission oil cooler lines from the radiator.
2. Pressure test the cooling system. Refer to Cooling System Leak Testing .
3. Inspect the transmission oil cooler for coolant.

Is coolant present in the transmission oil cooler?

Go to Step 29

Go to Step 30

29 |

1. Replace the radiator. Refer to Radiator Replacement .
2. Service the automatic transmission. Refer to Engine Coolant/Water in Transmission .

Is the repair complete?

Go to Step 36

--

30 | Install the cooler lines to the radiator. Is the action complete? | Go to Step 36 | --
31 | Repair the engine no crank condition. Refer to Engine Will Not Crank - Crankshaft Will Not Rotate . Is the repair complete? | Go to Step 36 | --
32 | Repair the engine overheating condition. Refer to Engine Overheating . Is the repair complete? | Go to Step 36 | --
33 | Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or Coolant in Engine Oil . Is the repair complete? | Go to Step 36 | --
34 | Repair the engine knock. Refer to Lower Engine Noise, Regardless of Engine Speed . Is the repair complete? | Go to Step 36 | --
35 | Repair the combustion pressure in the cooling system problem. Refer to Coolant in Combustion Chamber . Is the repair complete? | Go to Step 36 | --
36 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2