Chevrolet Silverado / GMC Sierra. Service manual — part 1021

Fig. 12: 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: 24°C (75°F)

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - 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 - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Fig. 13: Connecting J 45096 Adapters To Oil Cooler Supply And Return Lines
Courtesy of GENERAL MOTORS CORP.

1. Connect the J 45096 adapters (1) to the vehicle transmission oil cooler supply and return

lines at the transmission, may require J 35944-200 . See Special Tools.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Fig. 14: Identifying Black Supply Hose And Clear Waste Hose
Courtesy of GENERAL MOTORS CORP.

2. Connect the black supply hose (1) to the return line, top connector of the transmission, and

the clear waste hose (2) to the feed line, bottom connector of the transmission, to the vehicle
cooler lines. This is the reverse flow backflush direction.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado