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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 98 (Engine Cooling System) >> Diagnostic Information and Procedures >> Loss of Coolant

Loss of Coolant

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
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 System Check - Vehicle .
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 Draining and Filling Cooling System .
Is the action complete?		 Go to Step 5  -
5 Engine overheating can cause a loss of coolant.
Is the engine overheating?		 Go to Step 19  Go to Step 6 
6
  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 7  Go to Step 8 
7
  • 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 20  Go to Step 8 
8 Visually inspect the hoses, pipes and hose clamps.
Are any of the hoses, clamps or pipes leaking?		 Go to Step 21  Go to Step 9 
9 Visually inspect the following components:
  • Block heater
  • Coolant pressure cap
  • Core plugs
  • Throttle body
  • Engine block
  • Intake manifold
  • Radiator
  • Thermostat housing
  • Water pump

Are any of the listed components leaking?		 Go to Step 21  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 7 and 8.
Are any leaks present?		 Go to Step 21  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 16 
12 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 21  Go to Step 13 
13 Inspect the underside of the engine oil fill cap for a gray/white milky substance.
Is there a milky substance under the oil fill cap?		 Go to Step 14  Go to Step 15 
14 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 17  Go to Step 15 
15 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 18  Go to Step 22 
16 Replace the coolant pressure cap.
Is the repair complete?		 Go to Step 22  -
17
  1. Replace the radiator. Refer to Radiator Replacement .
  2. Replace the oil and filter. Refer to Engine Oil and Oil Filter Replacement
Is the repair complete?		 Go to Step 22  -
18
  1. Replace the radiator. Refer to Radiator Replacement .
  2. Service the automatic transmission. Refer to one of the following:
Is the repair complete?		 Go to Step 22  -
19 Repair the engine overheating condition. Refer to Engine Overheating .
Is the repair complete?		 Go to Step 22  -
20 Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or, Coolant in Engine Oil .
Is the repair complete?		 Go to Step 22  -
21 Repair or replace the leaking component. Refer to the appropriate repair.
Is the repair complete?		 Go to Step 22  -
22 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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