Transmission Fluid Cooler Tubes - Backflushing and Cleaning

4R70E/4R75E

Transmission Fluid Cooler Tubes Backflushing and Cleaning

1. WARNING: Before servicing a vehicle equipped with a fire suppression system, depower the system by following the procedure in Fire Suppression System. Failure to follow the instructions may result in serious personal injury Procedures.

With the vehicle in NEUTRAL, position it on a hoist.

2. NOTICE: When internal wear/damage occurs in the transmission, metal particles, clutch plate material and band material can travel into the torque converter, the transmission fluid cooler tubes and the Oil-To-Air (OTA) transmission fluid cooler. These contaminates are a major cause of recurring transmission concerns. To prevent future concerns, remove these contaminants from the cooling system before placing the transmission back into use.

NOTICE: The Oil-To-Air (OTA) transmission fluid cooler is not repairable with existing equipment due to the thermostatic bypass valve. Do not attempt to backflush and clean the OTA transmission fluid cooler. Install a new OTA transmission fluid cooler if there is leakage from the OTA transmission fluid cooler, major metallic failure, multiple clutch or clutch plate failure, or sufficient component wear that result in metallic contamination.

Using a suitable torque converter/fluid cooler cleaner, clean the transmission fluid cooler tubes.

3. Test the equipment to make sure that a vigorous fluid flow is present before proceeding. Install a new filter in the flush equipment if the flow is weak or contaminated.

4. To aid in attaching the cleaner to the transmission steel cooler tubes, connect 2 additional rubber hoses to the transmission end of the steel transmission cooler tubes as follows:
- Disconnect the transmission fluid cooler tubes from the Oil-To-Air (OTA) transmission fluid cooler.

- Install a rubber hose in place of the OTA transmission cooler.

- Connect the cleaner tank pressure line to the steel transmission fluid cooler return tube (the longest tube).

- Connect a tank return hose to the steel transmission fluid cooler pressure tube (shorter tube). Place the outlet end of this hose in the fluid tank reservoir.

5. Turn on the pump and allow the fluid to circulate a minimum of 5 minutes (cycling switch ON and OFF will help dislodge contaminants in the cooler system).

6. Switch OFF the pump and disconnect the pressure hose from the transmission fluid cooler return tube.

7. Use compressed air to blow out the cooler(s) and tubes (blow air into the transmission fluid cooler return tube) until all fluid is removed.

8. Remove the rubber return hose from the remaining steel cooler tube.

9. Connect the OTA transmission fluid cooler tubes.

10. NOTICE: Contamination can become trapped in the transmission fluid coolers. Clean fluid flow after flushing does not always indicate all contamination has been removed.

Install a new OTA.

11. WARNING: If the vehicle is equipped with a fire suppression system, repower the system. For important safety warnings and procedures, refer to Fire Suppression System. Failure to follow these instructions may result in serious personal injury Procedures.

If equipped with a fire suppression system, repower the system.