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Chevrolet Silverado / GMC Sierra. Manual - part 1613
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5. Sufficiently cover the radiator grille to
restrict the air flow.
6. Start the engine.
7. Turn the A/C ON, if equipped.
8. Operate the engine at approximately 2,000
RPM.
9. Inspect the thermometer reading when the
fan clutch engages.
10. Do not continue this test if the fan clutch
does not engage between 85-96°C (185-
205°F).
Fan clutch engagement will be indicated by an
increase in fan air noise, fan speed, and a drop
of about 3-10°C (5-15°F) on the thermometer
reading.
Did the fan clutch engage between 85-96°C
(185-205°F)?
IMPORTANT:
Do not allow engine temperature to exceed
121°C (250°F).
Go to Step 12
Go to Step 14
12
Once the fan clutch engages, perform the
following steps:
1. Uncover the radiator grille.
2. Turn the A/C OFF, if equipped.
3. Operate the engine at approximately 2,500
RPM to reduce the engine operating
temperature.
4. Remove the thermometer.
Did the engine return to normal operating
temperature?
Go to Step 13
-
As the engine temperature returns to normal, the
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
REPAIR INSTRUCTIONS
COOLING SYSTEM DRAINING AND FILLING (VAC-N-FILL)
Tools Required
J 26568 Coolant and Battery Tester
GE-47716 Vac-N-Fill Coolant Refill Tool
J 42401 Radiator Cap and Surge Tank Test Adapter
Draining Procedure
1. Park the vehicle on a level surface.
2. Remove the coolant pressure cap.
3. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
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fan clutch will disengage, indicated by a
reduction in fan air noise and fan speed.
Did the fan clutch disengage?
Go to Step 16
Go to Step 14
14
Replace the fan clutch. Refer to Fan Clutch
Replacement (Diesel).
Is the repair complete?
Go to Step 16
-
15
Replace the fan blades. Refer to Fan
Replacement (Diesel) or Fan Replacement
(Mechanical).
Is the repair complete?
Go to Step 16
-
16
Operate the fan clutch to verify proper
operation.
Did you find and correct the condition?
System OK
Go to Step 2
CAUTION: With a pressurized cooling system, the coolant temperature in
the radiator can be considerably higher than the boiling point
of the solution at atmospheric pressure. Removal of the surge
tank cap, while the cooling system is hot and under high
pressure, causes the solution to boil instantaneously with
explosive force. This will cause the solution to spew out over
the engine, the fenders, and the person removing the cap.
Serious bodily injury may result.
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
4. Place a drain pan under the drain cock.
5. Open the radiator drain cock.
6. Drain the cooling system.
7. If a complete engine block drain is required, remove the engine block drain plug.
8. Inspect the coolant.
9. Follow the appropriate procedure based on the condition of the coolant.
Normal in appearance-Follow the filling procedure.
Discolored-Follow the flush procedure. Refer to Flushing .
Vac-N-Fill Procedure
1. Install the J 42401 .
IMPORTANT: To prevent boiling of the coolant/water mixture in the vehicles
cooling system, do not apply vacuum to a cooling system above
49°C (120°F). The tool will not operate properly wh en the coolant
is boiling.
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
