GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 STS 🢒 Engine 🢒 Engine Cooling 🢒 Loss of Coolant

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

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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 cylinder.

Does the engine crankshaft rotate?

Go to Step 6

Go to Step 23

6

Engine overheating can cause a loss of coolant.

Is the engine overheating?

Go to Step 24

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 26

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 25

Go to Step 10

10

With the engine idling, inspect the surge tank.

Does the surge tank 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:

    • Afterboil pump
    • Engine
    • Heater
    • Radiator
    • Surge tank

Are any of the hoses, clamps or pipes leaking?

Go to Step 19

Go to Step 12

12

Visually inspect the following components:

    • Core plugs
    • Cylinder head gaskets
    • Engine block
    • Intake manifold
    • Radiator
    • Thermostat
    • Water pump
    • Surge tank
    • Surge tank cap

Are any of the listed components leaking?

Go to Step 19

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 19

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 20

15

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

Does the coolant pressure cap hold pressure?

Go to Step 27

Go to Step 20

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 under the HVAC module

Is coolant present?

Go to Step 21

Go to Step 17

17

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 18

Go to Step 28

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 25

Go to Step 28

19

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

Is the repair complete?

Go to Step 28

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20

Replace the coolant pressure cap.

Is the repair complete?

Go to Step 28

--

21

Replace the heater core. Refer to Heater Core Replacement in Heating, Ventilation and Air Conditioning.

Is the repair complete?

Go to Step 28

--

22

Replace the radiator. Refer to Radiator Replacement .

Is the repair complete?

Go to Step 28

--

23

Repair the engine no crank condition. Refer to Engine Will Not Crank - Crankshaft Will Not Rotate in Engine Mechanical - 4.6L (LH2) or Engine Will Not Crank - Crankshaft Will Not Rotate in Engine Mechanical - 3.6L (LY7).

Is the repair complete?

Go to Step 28

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24

Repair the engine overheating condition. Refer to Engine Overheating .

Is the repair complete?

Go to Step 28

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25

Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or Coolant in Engine Oil in Engine Mechanical - 4.6L (LH2) or Coolant in Combustion Chamber or Coolant in Engine Oil in Engine Mechanical - 3.6L (LY7).

Is the repair complete?

Go to Step 28

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26

Repair the engine knock. Refer to Lower Engine Noise, Regardless of Engine Speed in Engine Mechanical - 4.6L (LH2) or Lower Engine Noise, Regardless of Engine Speed in Engine Mechanical - 3.6L (LY7).

Is the repair complete?

Go to Step 28

--

27

Repair the combustion pressure in the cooling system problem. Refer to Cylinder Leakage Test in Engine Mechanical - 4.6L (LH2) or Cylinder Leakage Test in Engine Mechanical - 3.6L (LY7).

Is the repair complete?

Go to Step 28

--

28

Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2