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 System Check - 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 6 | 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 a cylinder, the coolant can hydraulically lock the engine. Does the engine crankshaft rotate? | Go to Step 6 | Go to Step 26
6 | Engine overheating can cause a loss of coolant. Is the engine overheating? | Go to Step 27 | Go to Step 7
7 | Extended operation with a low coolant level can cause engine internal component failure. Is the engine knocking? | Go to Step 29 | 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 28

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:

• | Coolant surge tank

• | Heater core

• | Radiator

Are any of the hoses, clamps or pipes leaking?

Go to Step 20

Go to Step 12

12 | Visually inspect the following components:

• | The coolant pressure cap

• | The core plugs

• | The cylinder head gaskets

• | The engine block

• | The intake manifold

• | The radiator

• | The thermostat housing

• | The water pump

Are any of the listed components leaking?

Go to Step 20

Go to Step 13

13 |

1. Pressure test the cooling system. Refer to Cooling System Leak Testing .
2. With the cooling system pressurized, visually inspect the components listed in steps 11 and 12.

Are any leaks present?

Go to Step 20

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 21
15 | Pressure test the coolant pressure cap. Refer to Pressure Cap Testing . Does the coolant pressure cap hold pressure? | Go to Step 30 | Go to Step 21
16 | Inspect for the following conditions:

• | A coolant smell inside of the vehicle

• | Coolant in the HVAC module drain tube

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

Is coolant present?

Go to Step 22

Go to Step 17

17 | Inspect the underside of the engine oil fill cap for a gray/white milky substance. Is there a milky substance on under the oil fill cap? | Go to Step 18 | Go to Step 19
18 | 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 28 | Go to Step 19
19 | 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 23 | Go to Step 31
20 | Repair or replace the leaking component. Refer to the appropriate repair. Is the repair complete? | Go to Step 31 | --
21 | Replace the coolant pressure cap. Is the repair complete? | Go to Step 31 | --
22 | Replace the heater core. Refer to Heater Core Replacement in Heating, Ventilation and Air Conditioning. Is the repair complete? | Go to Step 31 | --
23 |

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?

Go to Step 24

Go to Step 25

24 |

1. Replace the radiator. Refer to Radiator Replacement .
2. Service the automatic transmission. Refer to Engine Coolant/Water in Transmission in Automatic Transmission - 4T40-E/4T45-E.

Is the repair complete?

Go to Step 31

--

25 | Install the cooler lines to the radiator. Is the action complete? | Go to Step 31 | --
26 | Repair the engine no crank condition. Refer to Engine Will Not Crank - Crankshaft Will Not Rotate in Engine Mechanical-2.2L (L61) or Engine Will Not Crank - Crankshaft Will Not Rotate in Engine Mechanical-3.0L (L81) . Is the repair complete? | Go to Step 31 | --
27 | Repair the engine overheating condition. Refer to Engine Overheating . Is the repair complete? | Go to Step 31 | --
28 | Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or Coolant in Engine Oil in Engine Mechanical-2.2L (L61) or Coolant in Combustion Chamber or Coolant in Engine Oil in Engine Mechanical-3.0L (L81). Is the repair complete? | Go to Step 31 | --
29 | Repair the engine knock. Refer to Lower Engine Noise, Regardless of Engine Speed in Engine Mechanical-2.2L (L61) or Lower Engine Noise, Regardless of Engine Speed in Engine Mechanical-3.0L (L81). Is the repair complete? | Go to Step 31 | --
30 | Repair the combustion pressure in the cooling system problem. Refer to Cylinder Leakage Test in Engine Mechanical-2.2L (L61) or Cylinder Leakage Test in Engine Mechanical-3.0L (L81). Is the repair complete? | Go to Step 31 | --
31 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2