Chevrolet Silverado / GMC Sierra. Service manual — part 1024

3. Disconnect the supply and waste hoses and the 12-volt power source from the vehicle.

Fig. 22: Applying Shop Air Supply Hose To Quick-Disconnect
Courtesy of GENERAL MOTORS CORP.

4. Disconnect the air supply hose from J 45096 . See Special Tools.

5. Dispose of the waste oil in accordance with all applicable federal, state, and local

requirements.

TRANSMISSION FLUID COOLER FLUSHING AND FLOW TEST (J 35944-A)

GM studies indicate that plugged or restricted transmission oil coolers and pipes cause

unit when the air supply is disconnected. This is a normal
operation of the built-in water separator.

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

insufficient transmission lubrication and elevated operating temperatures which can lead to
premature transmission wear-out. Many repeat repair cases could have been prevented by
following published procedures for transmission oil cooler flushing and flow checking. This
procedure includes flow checking and flushing the auxiliary transmission oil cooler, if equipped.

Only GM Goodwrench DEXRON®VI automatic transmission fluid should be used when doing a
repair on a GM transmission.

Time allowance for performing the cooler flow checking and flushing procedure has been
included in the appropriate labor time guide operations since the 1987 model year. The service
procedure steps for oil cooler flushing are as follows:

Cooler Flow Check and Flushing Steps

1. Tools Required

2. Preparation

IMPORTANT: Use the J 35944-A or equivalent to flush the transmission oil

cooler and the oil cooler pipes whenever the transaxle is
removed for the following repairs:. See Special Tools.

Torque converter

Oil pump

Oil pump drive shaft

Drive sprocket support

Transaxle overhaul complete

Transaxle assembly replacement

IMPORTANT: Use the J 35944-A or equivalent to flush the transmission oil

cooler and the oil cooler pipes whenever the transmission is
removed for the following repairs:. See Special Tools.

Torque converter

Oil pump

Turbine shaft

Transmission overhaul complete

Transmission assembly replacement

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

3. Back Flush

4. Forward Flush

5. Flow Check

6. Clean-up

Tools Required

J 35944-A Transmission Oil Cooler Flusher. See Special Tools.

J 35944-22 Transmission Oil Cooler Flushing Fluid. See Special Tools.

J 35944-200 Cooler Flushing Adapter. See Special Tools.

Measuring cup

Funnel

Water supply, hot water recommended

Water hose, at least 16 mm (5/8 in) ID

Shop air supply, with water/oil filters, regulator and pressure gage

Air chuck, with clip if available

Oil drain container

Pail with lid 19 L (5 gallon)

Eye protection

Rubber gloves

PREPARATION

1. During the installation of the repaired or replacement transmission, do not connect the oil

cooler pipes.

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

Fig. 23: Identifying Flusher Tank & Components
Courtesy of GENERAL MOTORS CORP.

NOTE:

Do not use solutions that contain alcohol or glycol. Use of
solutions that contain alcohol or glycol may damage the oil
cooler line flusher, oil cooler components and/or transmission
components.

IMPORTANT: The J 35944-22 is environmentally safe, yet powerful enough

to cut through transmission fluid to dislodge any
contaminants from the cooler. See Special Tools. The safety
precautions on the label, regarding potential skin and eye
irritations associated with prolonged exposure, are typical
precautions that apply to many similar cleaning solutions. It
should be noted that according to GM, use of other non-

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado