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Home >> Cadillac >> 2005 >> STS 3.6 7 >> Repair and Diagnosis >> Engine Mechanical >> Cooling System (Mechanical) >> Engine Cooling System >> Diagnostic Information and Procedures >> Loss of Coolant

Loss of Coolant

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  -
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 Draining and Filling Cooling System .
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  -
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 (LH2 Standard Cooling)  or Radiator Replacement (LH2 Heavy Duty Cooling)  or Radiator Replacement (LY7 Standard Cooling) .
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  -
24 Repair the engine overheating condition. Refer to Engine Overheating .
Is the repair complete?		 Go to Step 28  -
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  -
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 
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