Chevrolet Silverado / GMC Sierra. Service manual — part 1613

11

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 .

13

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

Fig. 6: Identifying Vac-N-Fill Cap
Courtesy of GENERAL MOTORS CORP.

2. Attach the Van-N-Fill cap to the vehicles coolant fill port.

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado