Transmission Fluid Cooler Flushing and Flow Test J45096

GM studies indicate that plugged or restricted transmission oil coolers and pipes cause insufficient transmission lubrication and elevated operating temperatures which can lead to premature transmission failure. 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.

Important: Use the J 45096 or equivalent to flush and flow test the transmission oil cooler and the oil cooler pipes after the transaxle is removed for repairs.

Only GM Goodwrench DEXRON®III 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 and flow testing are as follows:

1. Machine Set-up
2. Determine Minimum Flow Rate
3. Back Flush
4. Forward Flush
5. Flow Test
6. Code Recording Procedure
7. Clean-up

Tools Required

1. Verify that the main power switch (1) is in the OFF position.
2. Place the main function switch (2) in the IDLE position.



3. Connect J 45096 to the vehicle 12V DC power source by connecting the red battery clip to the positive, +, battery post on the vehicle and connect the negative lead to a known good chassis ground.
4. Turn the main power switch to the ON position.




Notice: Do not overfill the supply vessel. Damage to the unit may result. To verify the fluid level, view the LCD screen display while filling the unit, to ensure the fluid level does not exceed 30 L (32 qt).

5. Fill the supply tank with Dexron®III/Mercon®, or equivalent, through the fill port.
6. Reinstall and tighten the fill cap.



7. Connect a shop air supply hose to the quick-disconnect on the rear panel marked SUPPLY AIR.

1. From the machine display, identify the temperature of the automatic transmission fluid that is stored in the supply vessel of J 45096 .



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: 75°F

•	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 and refer to the appropriate GM service manual procedures.

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



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.



3. Turn the main function switch to the FLUSH position. Allow the machine to operate for 30 seconds.



4. Turn the main function switch to the IDLE position and allow the supply vessel pressure to dissipate.

1. Disconnect the supply and waste hoses from the vehicle cooler lines. Reverse the supply and waste hoses to provide a normal flow direction.



2. Turn the main function switch to the FLUSH position and allow machine to operate for 30  seconds.

Important: If the flow rate is less than 0.5 gpm, the LCD displays an error message. Refer to the Troubleshooting section of the operation manual.

1. Turn the main function switch to the FLOW position and allow the oil to flow for 15 seconds. Observe and note the flow rate; this is the TESTED flow rate.
2. Compare the TESTED flow rate to the MINIMUM flow rate information previously recorded.

•	If the TESTED flow rate is equal to or greater than the MINIMUM flow rate recorded, the oil cooling system is functioning properly. Perform Code Recording Procedure.

•	If the TESTED flow rate is less than the MINIMUM flow rate previously recorded, repeat the back flush and forward flush procedures.

3. If the TESTED flow rate is less than the MINIMUM flow rate after the second test, perform Code Recording Procedure.

3.1.	Replace the transmission oil cooler.

3.2.	Reconnect supply and waste hoses to the cooler lines in the normal flow direction. Perform Flow Test.

3.3.	Perform Code Recording Procedure.

1. Turn the main function switch to the CODE position.

Important: 

•	If power is interrupted prior to the recording of the seven-character code, the code will be lost and the flow rate test will need to be repeated.

•	The flow test must run for a minimum of 8-10 seconds and be above 0.5 gpm for a code to be generated.

2. Record TESTED flow rate, temperature, cycle and seven-character flow code information on repair order.

1. Turn the main function switch (2) to the IDLE position and allow the supply vessel pressure to dissipate.
2. Turn the main power switch (1) to the OFF position.
3. Disconnect the supply and waste hoses and the 12-volt power source from the vehicle.

Note: A small amount of water may drain from the bottom of the unit when the air supply is disconnected. This is a normal operation of the built-in water separator.




4. Disconnect the air supply hose from J 45096 .
5. Dispose of the waste ATF in accordance with all applicable federal, state, and local requirements.

Transmission Fluid Cooler Flushing and Flow Test J 35944-A

Tools Required

1. Remove the fill cap on the J 35944-A and fill with 0.6 liter (20 oz) of the J 35944-22 .

•	Do not overfill.

•	Follow the manufacturer's suggested procedures for handling the solution.

2. Install the cap on the J 35944-A and pressurize the J 35944-A to 550-700 kPa (80-100 psi).
3. Connect the J 35944-A to the transmission end of the oil cooler pipe that feeds the bottom fitting of the oil cooler.
4. Connect the discharge hose to the top oil cooler pipe.
5. Clip the discharge hose to the oil drain container.
6. With the water valve on the J 35944-A in the OFF position, connect the water supply to the tool.
7. Turn on the water supply.

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.

8. Flush the transmission fluid by opening the water valve to the ON position for 10 seconds.
9. Close the water valve and clip the discharge hose to a 5 gallon pail.
10. Cover the pail with a shop towel in order to prevent splash.
11. Turn the water valve to the ON position and depress the trigger in order to mix the flushing solution into the water flow.
12. Use the bale clip provided in order to hold the trigger down.
13. Flush the cooler with water and the solution for 2 minutes. During this flush, attach an air supply to the air valve located on the tool for 3 to 5 seconds every 15 to 20 seconds. This will create a surging action to ensure complete cleaning.
14. Release the trigger and turn off the water valve.
15. Disconnect both hoses from the oil cooler pipes in order to perform an initial flush.
16. Reconnect the hoses to the pipes opposite the initial flush to do a backflush.
17. Turn the water valve to the ON position and depress the trigger in order to mix the flushing solution into the water flow.
18. Use the bale clip provided in order to hold the trigger down.
19. Flush the cooler with water and the solution for 2 minutes. During this flush, attach an air supply to the air valve located on the tool for 3 to 5 seconds every 15 to 20 seconds. This will create a surging action to ensure complete cleaning.
20. Release the trigger. Rinse with water for 1 minute.
21. Turn off the water valve.
22. Attach the air supply to the air valve.
23. Dry the system with air until no moisture is seen leaving the discharge hose.
24. Connect the cooler feed pipe to the transmission.

The cooler feed is the TOP connector at the transmission.

25. Clip the discharge hose to the oil drain container.
26. After filling the transmission with fluid, start the engine.
27. Run the engine for 30 seconds to remove the residual moisture from the oil cooler.

At least 2 quarts of the fluid should flow during the 30 second period.

28. If the fluid flow was insufficient, check flow from the transmission by disconnecting the feed line at the cooler and observing the flow for another 30 seconds.

Check for the following conditions:

•	Insufficient Flow -- Inspect the transmission for causes.

•	Sufficient Flow -- Inspect the cooler pipes, fittings and repeat the cooler flushing procedure. If the flow is still insufficient, replace the cooler.

29. Remove the discharge hose and reconnect the cooler pipes.

Adjust the fluid level.