GM Service Manual Online
For 1990-2009 cars only

Preparation

Tools Required

    • J 35944-A Oil Cooler and Line Flusher
    • J 35944-22 Cooler Flushing Fluid

Whenever you remove a transmission for service, do a transmission oil cooler flushing. It is essential to flush the oil cooler under the following conditions:

    • After a major overhaul
    • Suspected contamination
    • Pump or torque converter replacement
        For complete transmission service, perform the flush procedure after the overhauled or replacement assembly is installed in the vehicle.
  1. Remove the fill cap on the J 35944-A .
  2. Fill the can with 0.6 liter ( 20-21 ounces) of J 35944-22 , or equivalent, cooler flushing fluid. Do not overfill. If you overfill, the tool will need recharging with air before the backflush.
  3. Follow the manufacturer's suggested procedures for proper handling of the solution.
  4. Important: Shop air supply must not exceed 825 kPa (120 psi), and must be equipped with a water/oil filter.

  5. Secure the fill cap, and pressurize the flusher can with shop air to 550-700 kPa (80-100 psi).
  6. Connect the J 35944-A to the transmission end of the transmission cooler pipe that feeds the bottom fitting of the oil cooler.
  7. Connect the discharge hose to the top oil cooler pipe.
  8. Clip the discharge hose to the oil drain container.
  9. With the water valve on the tool in the OFF position, connect the water hose from the water supply to the tool.
  10. Turn ON the water supply at the faucet.

Initial Flushing

    Important: If water does not flow through the cooler the system is completely plugged. Do not complete the flushing procedure. Replace the cooler and/or the cooler pipes as required.

  1. Switch the water valve on the tool to the ON position. Allow the water to flow through the oil cooler for 10 seconds in order to remove the transmission fluid in the system.
  2. Switch the water valve on the tool to the OFF position. Clip the discharge hose onto a 5 gallon pail with a lid. If there is no lid, place a shop towel over the end of the hose in order to prevent splash. The discharge will foam vigorously when you introduce solution into the water stream.
  3. Switch the water valve on the tool to the ON position. Depress the trigger that mixes the flushing solution into the water flow. Use the bale clip on the handle in order to hold down the trigger.
  4. Flush the oil cooler with water and solution for 2 minutes. During the flush, attach the air supply to the air valve on the tool for 3-5 seconds after every 15-20 second interval in order to create a surging action.
  5. Release the trigger. Switch the water valve on the tool to the OFF position.
  6. Disconnect both hoses from the oil cooler pipes.

Backflush

  1. Connect the hoses to the oil cooler pipes in order to perform a backflush.
  2. Switch water valve on the tool to the ON position. Depress the trigger in order to mix the flushing solution with the water flow. Use the bale clip on the handle to hold down the trigger.
  3. Flush the oil cooler with water and solution for 2 minutes. During this flush, attach the air supply to the air valve on the tool for 3-5 seconds after each 15-20 second interval in order to create a surging action.
  4. Release the trigger. Allow water only to rinse the oil cooler for 1 minute.
  5. Turn the water supply OFF at the faucet.
  6. Attach the air supply to the air valve on the tool. Dry out the system with air for at least 2 minutes. Dry out the system longer than 2 minutes, if moisture from the oil cooler line discharge hose is visible.
  7. Connect the cooler feed pipe to the transmission. The cooler feed is the bottom connection at the transmission.
  8. If not already connected, attach the discharge hose to the cooler return pipe. Place the hose into an appropriate drain container.
  9. After filling the transmission with DEXRON®-III or DEXRON®-IIE automatic transmission fluid, or equivalent, start the engine. Run the engine for 30 seconds. This removes any residual moisture from the oil cooler and the cooler pipes, protects all the components from corrosion, and checks the flow rate through the cooler.
  10. You should get a minimum of 1.9 liters (2 quarts) of transmission fluid during this 30 second run. If the flow of fluid is insufficient, disconnect the oil cooler feed line at the radiator and restart the engine.
  11. If there is insufficient flow inspect the transmission for cause. Inspect the cooler pipes and fittings. Repeat the cooler flushing procedure. Replace the cooler if the flow is still insufficient.
  12. Remove the discharge hose.
  13. Reconnect the cooler return pipe to the transmission.
  14. Refill the unit to the proper fluid level.