Chevrolet Silverado / GMC Sierra. Manual - part 744
5. Fill the supply tank with Dexron®VI through the fill port.
6. Reinstall and tighten the fill cap.
Fig. 12: Applying Shop Air Supply Hose To Quick-Disconnect
Courtesy of GENERAL MOTORS CORP.
7. Connect a shop air supply hose to the quick-disconnect on the rear panel marked SUPPLY
AIR.
DETERMINE MINIMUM FLOW RATE
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
Fig. 13: Identifying Machine Display Of Automatic Transmission Fluid
Temperature
Courtesy of GENERAL MOTORS CORP.
1. From the machine display, identify the temperature of the automatic transmission fluid that
is stored in the supply vessel of J 45096 .
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
Fig. 14: Identifying Transmission Oil Cooler Metal Composition
Courtesy of GENERAL MOTORS CORP.
2. Determine whether the transmission oil cooler is steel or aluminum by using a magnet (1) at
the cooler flange (2) at the radiator.
3. Refer to the table below. Using the temperature from step 1, locate on either the Steel
MINIMUM Flow Rate table or the Aluminum MINIMUM Flow Rate table the minimum
flow rate in gallons per minutes (GPM). Record the minimum flow rate in GPMs and the
supply fluid temperature for further reference.
Example:
Fluid temperature: 75°F
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
Cooler type: Steel
The MINIMUM flow rate for this example would be 0.8 GPM.
4. Inspect transmission oil cooler lines for damage or kinks that could cause restricted oil flow.
Repair as needed.
Minimum Flow Rate in Gallons Per Minute (gpm)
BACK FLUSH PROCEDURE
Temperature Range
Steel
Aluminum
65 - 66°F
0.6 gpm
0.5 gpm
67 - 70°F
0.7 gpm
0.6 gpm
71 - 75°F
0.8 gpm
0.7 gpm
76 - 80°F
0.9 gpm
0.8 gpm
81 - 84°F
1.0 gpm
0.9 gpm
85 - 89°F
1.1 gpm
1.0 gpm
90 - 94°F
1.2 gpm
1.1 gpm
95 - 98°F
1.3 gpm
1.2 gpm
99 - 103°F
1.4 gpm
1.3 gpm
104 - 108°F
1.5 gpm
1.4 gpm
109 - 112°F
1.6 gpm
1.5 gpm
113 - 117°F
1.7 gpm
1.6 gpm
118 - 120°F
1.8 gpm
1.7 gpm
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado