Transmission Cooler: Service and Repair

FLUSHING COOLERS AND TUBES
When a transaxle failure has contaminated the fluid, the oil cooler (s) must be flushed. The cooler bypass valve in the transaxle must be replaced also. The torque converter must also be replaced with an exchange unit. This will insure that metal particles or sludged oil are not later transferred back into the reconditioned (or replaced) transaxle.

There are two different procedures for flushing coolers and lines. The recommended procedure is to use Tool 6906 Cooler Flusher, or equivalent. The other procedure is to use a hand suction gun and mineral spirits.

WARNING:
- Wear protective eye-wear that meets the requirements of OSHA and ANSI Z87.1-1968. wear standard industrial rubber gloves.

- Keep lighted cigarettes, sparks, flames, and other ignition sources away from the area to prevent the ignition of combustible liquids and gases. Keep a class (B) fire extinguisher in the area where the flusher will be used.

- Keep the area well ventilated.

- Do not let flushing solvent come in contact with your eyes or skin: if eye contamination occurs, flush eyes with water for 15 to 20 seconds. Remove contaminated clothing and wash affected skin with soap and water. Seek medical attention.

Cooler Flush Using Tool 6906, or Equivalent
1. Remove cover plate filler plug on Tool 6906, or equivalent. Fill reservoir 1/2 to 3/4 full of fresh flushing solution. Flushing solvents are petroleum based solutions generally used to clean automatic transmission components. DO NOT use solvents containing acids, water, gasoline, or any other corrosive liquids.
2. Reinstall filler plug on Tool 6906, or equivalent.
3. Verify pump power switch is turned OFF. Connect red alligator clip to positive (+) battery post. Connect black (-) alligator clip to a good ground.
4. Disconnect the cooler lines at the transmission.

NOTE: When flushing transmission cooler and lines, ALWAYS reverse flush.

5. Connect the BLUE pressure line to the OUTLET (From) cooler line.
6. Connect the CLEAR return line to the INLET (To) cooler line
7. Turn pump ON for two to three minutes to flush cooler(s) and lines. Monitor pressure readings and clear return lines. Pressure readings should stabilize below 20 psi. for vehicles equipped with a single cooler and 30 psi. for vehicles equipped with dual coolers. If flow is intermittent or exceeds these pressures, replace cooler.
8. Turn pump OFF.
9. Disconnect CLEAR suction line from reservoir at cover plate. Disconnect CLEAR return line at cover plate, and place it in a drain pan.
10. Turn pump ON for 30 seconds to purge flushing solution from cooler and lines. Turn pump OFF.
11. Place CLEAR suction line into a one quart container of MOPAR type 9602 automatic transmission fluid, or equivalent.
12. Turn pump ON until all transmission fluid is removed from the one quart container and lines. This purges any residual cleaning solvent from the transmission cooler and lines. Turn pump OFF.
13. Disconnect alligator clips from battery. Reconnect flusher lines to cover plate, and remove flushing adapters from cooler lines.

Cooler Flush Using Suction Gun And Mineral Spirits
1. Disconnect the cooler lines at the transmission.
2. Using a hand suction gun filled with mineral spirits, reverse flush the cooler. Force mineral spirits into the From Cooler line of the cooler and catch the exiting spirits from the To Cooler line. Observe for the presence of debris in the exiting fluid. Continue until fluid exiting is clear and free from debris.
3. Using compressed air (under 40 psi) in intermittens spurts, blow any remaining mineral spirits from the cooler, again in the reverse direction.
4. Pump one (1) quart of automatic transmission fluid through the cooler before reconnecting.
5. If at any stage of the cleaning process, the cooler does not freely pass fluid, the cooler must be replaced.

OIL COOLER FLOW CHECK
After the new or repaired transmission has been installed and filled, the oil cooler flow should be checked using the following procedure:
1. Disconnect the From Cooler line at the transmission and place a collecting container under the disconnected line.
2. Run the engine at curb idle speed, with the shift selector in NEUTRAL.
3. If the fluid flow is intermittent or takes more than 20 seconds to collect one quart, the cooler should be replaced.

CAUTION: With the fluid set at the proper level, fluid collection should not exceed (1) quart, or internal damage to the transmission may occur.

4. If flow is found to be within acceptable limits, reconnect the cooler line. Then fill transaxle to the proper level, using the approved type of automatic transmission fluid.