GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Chevy C Pickup - 2WD 🢒 Engine 🢒 Engine Electrical 🢒 Transmission Fluid Cooler Flushing

Oil Cooler Flushing

Tools Required

    • J 35944-A Cooler Flushing Tool
    • J 35944-22 Biodegradable Flushing Solution

Notice: Whenever you remove the transmission for service, you must perform the automatic transmission oil cooler flushing procedure in order to remove the existing fluid which may be contaminated. This will prevent contamination of the new fluid. You must perform the flushing procedure after the installation of the overhauled or replacement transmission.

Notice: Only use J 35944-20 Cooler Flushing Fluid with the J 35944-A Oil Cooler and Line Flusher. Use of any other fluid can result in damage to the tool, damage to the automatic transmission oil cooler components, or improper flushing of the cooler. Do not reconnect the oil cooler pipes after you reinstall the overhauled or service replacement transmission in the vehicle.

  1. Remove the fill cap on J 35944-A .
  2. Fill the can with 0.6 liter ( 20-21 ounces) of J 35944-22
  3. Follow the manufacturer's suggested procedures for proper handling of the solution.

    4. Notice: Shop air supply must be equipped with a water/oil filter and not exceed 825 kPa (120 psi), or personal injury may result.

  4. Secure the fill cap, and pressurize the flusher can with shop air to 550-700 kPa (80-100 psi).
  5. Connect the discharge hose to the transmission end of the air cooler pipe that goes to the top fitting at the radiator.
  6. Clip the discharge hose to the oil drain container.
  7. Mount the flushing tool to the undercarriage of the vehicle with the hook provided.
  8. Connect the hose from the flushing tool to the remaining oil cooler pipe.
  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

    Notice: If water does not flow through the oil cooler (system is completely plugged), do not continue the flushing procedure, or damage to the tool or components could result. Turn the water OFF immediately. Inspect the pipes and the cooler for restrictions. Replace the oil pipe(s) and/or the oil cooler.

  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 to 5 seconds after every 15 to 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
    • Connect the hoses to the oil cooler pipes opposite from the initial flush in order to perform a backflush.
    • Switch the 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.
    • 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 to 5 seconds after each 15 to 20 second interval in order to create a surging action.
    • Release the trigger. Allow water only to rinse the oil cooler for 1 minute.
    • Switch the water valve on the tool to the OFF position.
    • Turn the water supply OFF at the faucet.
    • 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. If available, use an air chuck clip to secure the air chuck onto the air valve for ease of operation.

       Important: The top fitting at the transmissions the cooler return. The bottom fitting at the transmission is the cooler feed.

    • Connect the cooler feed pipe to the transmission.
    • If not already connected, attach the discharge hose to the cooler return pipe. Place the hose into an appropriate drain container.
    • After filling the transmission with DEXRON®-III 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.
        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.
        Depending on the flow rate, do the following inspections:
      • Insufficient Feed Flow -- Inspect the transmission for the cause.
      • Sufficient Feed Flow -- Inspect the oil cooler pipes and the fittings for restrictions or leaks. Repeat the oil cooler flushing procedure. Repeat the check of fluid flow out of the return line. If the flow is still restricted, replace the transmission oil cooler. Refer to Oil Cooler Hose/Pipe Replacement .
    • Remove the discharge hose.
    • Reconnect the cooler return pipe to the transmission.
    • Refill the unit to the proper fluid level. Refer to Transmission Fluid Check .

Tool Cleaning Procedure

  1. Clean the tool with every third use.
  2. Disconnect the water supply hose from the tool.
  3. Bleed air pressure from the can, remove the fill cap, return any unused solution to the container and rinse the can out with water. Do not store the tool with the solution in the tank.
  4. Remove the screen from the plumbing and wash it with water.
  5. Use the cleaning pin in order to remove any material in the solution orifice. The orifice is located in the plumbing below the screen.
  6. Reconnect the plumbing and fill the can half with water. Secure the fill cap and pressurize the can to 550-700 kPa (80-100 psi).
  7. Aim the tool into the 18.92 Litre (5 gallon) pail or floor drain and depress the trigger. Allow the water from the can to flow through the solution orifice for 30 seconds in order to ensure proper cleaning.
  8. Bleed air pressure from can, remove the fill cap, and empty the can.
  9. Reconnect the fill cap to the flushing tool.