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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2007 🢒 STS 🢒 General Information 🢒 General Information 🢒 Loss of Coolant

Loss of Coolant LC3

Step

Action

Yes

No

DEFINITION: The cooling system is losing coolant either internally or externally.

1

Were you sent here from Symptoms or another diagnostic table?

Go to Step 2

Refer to Symptoms - Engine Cooling

2

Repair any present DTCs. Refer to Diagnostic Starting Point - Vehicle .

Is the action complete?

Go to Step 3

--

3

Inspect the coolant level at the surge tank.

Is the coolant at the proper level?

Go to Step 4

Go to Step 5

4

Inspect the charge air cooling system coolant level.

Is the coolant at the proper level?

Go to Step 7

Go to Step 6

5

Fill the cooling system to the proper level. Refer to Cooling System Draining and Filling .

Is the action complete?

Go to Step 4

--

6

Fill the charge air cooling system to the proper level. Refer to Charge Air Cooling System Draining and Filling .

Is the action complete?

Go to Step 7

--

7

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 8

Go to Step 29

8

Engine overheating can cause a loss of coolant.

Is the engine overheating?

Go to Step 30

Go to Step 9

9

Extended operation with a low coolant level can cause engine internal component failure.

Is the engine knocking?

Go to Step 32

Go to Step 10

10

Visually inspect the hoses, pipes and hose clamps at the following locations:

    • Radiator--Charge air cooler
    • Pump--Charge air cooler
    • Charge air cooler
    • Fill neck--Charge air cooler
    • Overflow reservoir--Charge air cooler

Are any of the hoses, clamps or pipes leaking?

Go to Step 25

Go to Step 11

11

Visually inspect the following components:

    • Radiator--Charge air cooler
    • Pump--Charge air cooler
    • Charge air cooler
    • Charge air coolant cap
    • Fill neck--Charge air cooler
    • Overflow reservoir--Charge air cooler

Are any of the listed components leaking?

Go to Step 25

Go to Step 12

12
  1. Pressure test the charge air cooling system. Refer to Cooling System Leak Testing .
  2. With the cooling system pressurized, visually inspect the components listed in steps 10 and 11.

Are any leaks present?

Go to Step 25

Go to Step 13

13

Visually inspect the hoses, pipes and hose clamps at the following locations:

    • Surge tank
    • Throttle body
    • Water pump
    • Heater core
    • Radiator

Are any of the hoses, clamps or pipes leaking?

Go to Step 25

Go to Step 14

14

Visually inspect the following components:

    • Block heater
    • Coolant pressure cap
    • Core plugs
    • Cylinder head gaskets
    • Cylinder heads
    • Engine block
    • Radiator
    • Thermostat housing
    • Water pump

Are any of the listed components leaking?

Go to Step 25

Go to Step 15

15
  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 13 and 14.

Are any leaks present?

Go to Step 25

Go to Step 16

16

Pressure test the coolant pressure cap. Refer to Pressure Cap Testing .

Does the coolant pressure cap hold pressure?

Go to Step 17

Go to Step 26

17
  1. Apply the parking brake.
  2. Ensure the vehicle is in PARK.
  3. Start and idle the engine until it reaches normal operating temperature.
  4. Inspect for heavy white smoke coming out of the exhaust pipe.

Is a heavy white smoke present from the exhaust pipe?

Go to Step 18

Go to Step 19

18
    • 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 31

Go to Step 19

19

Caution: Refer to Moving Parts and Hot Surfaces Caution in the Preface section.

With the engine idling, inspect the surge tank.

Does the surge tank discharge coolant while the engine is idling?

Go to Step 33

Go to Step 20

20

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 27

Go to Step 21

21
  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?

Step 25

Step 22

22

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?

Step 27

Step 23

23

Inspect the engine oil for a gray/white milky substance.

Is there a milky substance in the engine oil ?

Go to Step 31

Go to Step 24

24

Inspect the transmission oil fluid for a gray/white milky substance.

Does the transmission fluid contain a gray/white milky substance?

Go to Step 28

Go to Step 34

25

Repair or replace the leaking component. Refer to the appropriate repair.

Is the repair complete?

Go to Step 34

--

26

Replace the coolant pressure cap.

Is the repair complete?

Go to Step 34

--

27

Replace the heater core. Refer to Heater Core Replacement .

Is the repair complete?

Go to Step 34

--

28
  1. Replace the radiator. Refer to Radiator Replacement .
  2. Service the transmission. Refer to Engine Coolant/Water in Transmission .

Is the repair complete?

Go to Step 34

--

29

Repair the engine no crank condition. Refer to Engine Will Not Crank - Crankshaft Will Not Rotate .

Is the repair complete?

Go to Step 34

--

30

Repair the engine overheating condition. Refer to Engine Overheating .

Is the repair complete?

Go to Step 34

--

31

Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or Coolant in Engine Oil .

Is the repair complete?

Go to Step 34

--

32

Repair the engine knock. Refer to Lower Engine Noise, Regardless of Engine Speed .

Is the repair complete?

Go to Step 34

--

33

Repair the combustion pressure in the cooling system problem. Refer to Cylinder Leakage Test .

Is the repair complete?

Go to Step 34

--

34

Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2

Loss of Coolant LH2 and LY7

Step

Action

Yes

No

DEFINITION: The cooling system is losing coolant either internally or externally.

1

Were you sent here from Symptoms or another diagnostic table?

Go to Step 2

Refer to Symptoms - Engine Cooling

2

Repair any present DTCs. Refer to Diagnostic Starting Point - Vehicle .

Is the action complete?

Go to Step 3

--

3

Inspect the coolant level at the surge tank.

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 a cylinder, the coolant can hydraulically lock the engine.

Does the engine crankshaft rotate?

Go to Step 6

Go to Step 24

6

Engine overheating can cause a loss of coolant.

Is the engine overheating?

Go to Step 25

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 27

Go to Step 8

8

Visually inspect the hoses, pipes and hose clamps at the following locations:

    • Surge tank
    • Throttle body
    • Water pump
    • Heater core
    • Radiator

Are any of the hoses, clamps or pipes leaking?

Go to Step 20

Go to Step 9

9

Visually inspect the following components:

    • Block heater
    • Coolant pressure cap
    • Core plugs
    • Cylinder head gaskets
    • Cylinder heads
    • Engine block
    • Radiator
    • Thermostat housing
    • Water pump

Are any of the listed components leaking?

Go to Step 20

Go to Step 10

10
  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 8 and 9.

Are any leaks present?

Go to Step 20

Go to Step 11

11

Pressure test the coolant pressure cap. Refer to Pressure Cap Testing .

Does the coolant pressure cap hold pressure?

Go to Step 12

Go to Step 21

12
  1. Apply the parking brake.
  2. Ensure the vehicle is in PARK.
  3. Start and idle the engine until it reaches normal operating temperature.
  4. Inspect for heavy white smoke coming out of the exhaust pipe.

Is a heavy white smoke present from the exhaust pipe?

Go to Step 13

Go to Step 14

13
    • 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 26

Go to Step 14

14

Caution: Refer to Moving Parts and Hot Surfaces Caution in the Preface section.

With the engine idling, inspect the surge tank.

Does the surge tank discharge coolant while the engine is idling?

Go to Step 28

Go to Step 15

15

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 16

16
  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 20

Go to Step 17

17

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 22

Go to Step 18

18

Inspect the engine oil for a gray/white milky substance.

Is there a milky substance in the engine oil ?

Go to Step 26

Go to Step 19

19

Inspect the transmission oil fluid for a gray/white milky substance.

Does the transmission fluid contain a gray/white milky substance?

Go to Step 23

Go to Step 29

20

Repair or replace the leaking component. Refer to the appropriate repair.

Is the repair complete?

Go to Step 29

--

21

Replace the coolant pressure cap.

Is the repair complete?

Go to Step 29

--

22

Replace the heater core. Refer to Heater Core Replacement .

Is the repair complete?

Go to Step 29

--

23
  1. Replace the radiator. Refer to Radiator Replacement .
  2. Service the transmission. Refer to Engine Coolant/Water in Transmission .

Is the repair complete?

Go to Step 29

--

24

Repair the engine no crank condition. Refer to Engine Will Not Crank - Crankshaft Will Not Rotate .

Is the repair complete?

Go to Step 29

--

25

Repair the engine overheating condition. Refer to Engine Overheating .

Is the repair complete?

Go to Step 29

--

26

Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or Coolant in Engine Oil .

Is the repair complete?

Go to Step 29

--

27

Repair the engine knock. Refer to Lower Engine Noise, Regardless of Engine Speed .

Is the repair complete?

Go to Step 29

--

28

Repair the combustion pressure in the cooling system problem. Refer to Cylinder Leakage Test .

Is the repair complete?

Go to Step 29

--

29

Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2