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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1626 (Automatic Transmission - 4L80-E - Service & Replacement) >> Diagnostic Information and Procedures >> Automatic Transmission Oil Cooler Flushing and Flow Test >> Back Flush

Back Flush

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Inspect the transmission oil cooler pipes for kinks or damage. Repair as necessary.
    Fig 1: Identifying J 35944-A Water Supply Valve Position (1 Of 2)
    G01952238Courtesy of GENERAL MOTORS CORP.
  2. Connect the J 35944-A  to the oil cooler feed front connector. Use the J 35944-200,  if required.
  3. Clip the discharge hose (2) onto the oil drain container.
  4. Attach the J 35944-A  to the undercarriage of the vehicle with the hook provided and connect the flushing system feed supply hose (1) from the J 35944-A  to the rear connector oil cooler return pipe. Use the J 35944-200,  if required.
  5. Turn the J 35944-A  water supply valve (3) to the ON position and allow water to flow through the oil cooler and pipes for 10 seconds to remove any remaining transmission fluid. If water does not flow through the oil cooler and pipes, the cause of the blockage must be diagnosed and the plugged component must be repaired or replaced. Continue with the cooler flushing and flow check procedure once the blockage is corrected.
  6. Turn the J 35944-A  water supply valve (3) to the OFF position and clip the discharge hose onto a 19 liter (5 gallon) pail with a lid, to avoid splashback.
    Fig 2: Identifying J 35944-A Water Supply Valve Position (2 Of 2)
    G01952239Courtesy of GENERAL MOTORS CORP.
    IMPORTANT: Flushing for approximately 2 minutes in each cooler line direction will result in a total of about 8-10 gallons of waste fluid. This mixture of water and flushing fluid is to be captured in a bucket or similar container.
  7. Turn the J 35944-A  water supply valve (3) to the ON position and depress the trigger (1) to mix cooler flushing solution into the water flow. Use the clip provided on the handle to hold the trigger (1) down. The discharge will foam vigorously when the solution is introduced into the water stream.
  8. Flush the oil cooler and pipes with water and solution for 2 minutes. During this flush, attach the shop air supply 825 kPa (120 psi) to the flushing system feed air valve (2) located on the J 35944-A,  for 3-5 seconds at the end of every 15-20 second interval to create a surging action.
  9. Release the trigger (1) and turn the J 35944-A  water supply valve (3) to the OFF position.
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