A/T OIL COOLER FLUSHING ALL THM A/T MODELS

MODELS AFFECTED: ALL MODELS

NOTE: This bulletin supersedes all transmission oil cooler flushing information published prior to this date.

Transmission oil cooler flushing must be performed whenever a transmission/transaxle is removed for service. It is essential to flush the oil cooler after SRTA installation, major overhaul, if fluid contamination is suspected, or in any case of pump or torque converter replacement. A new, essential cooler flushing tool, Kent-Moore Number J35944 (Refer to Figure 1), has been developed to properly flush the oil cooler and will be shipped to GM dealers by December, 1986. Time allowance for performing the cooler flushing procedure will be included in specific 1987 Labor Time Guide operations. When using 1986, and prior, Labor Time Guides, add 0.6 hours for cooler flushing to the recondition or SRTA replacement time allowances.

To ensure complete transmission/transaxle system service, it is recommended that the flush procedure be perfomed after the overhauled or replacement assembly has been reinstalled in the vehicle.

The service procedure steps for oil cooler flushing are as follows:

EQUIPMENT AND MATERIALS NEEDED

Kent-Moore Cooler Flusher Tool, J35944 and biodegradable flushing solution* Measuring Cup (supplied with tool) Funnel Water Supply (hot water recommended in all cases, if available) Water Hose (at least 5/8 inch diameter) Air Supply (with water and oil filter) Air Chuck (with clip if available) Air Pressure Gage Oil Drain Container Five Gallon Pail (or larger, with lid) . Eye Protection Rubber Gloves

* Solution available by the gallon, J35944-20, or six-gallon case J35944-CSE.

PREPARATION

1. After overhauled or service replacement, transmission/transaxle is reinstalled, in vehicle; do not reconnect oil cooler pipes.

2. Remove fill cap on tool and fill can with 0.6 liter (20-21 ounces) of Kent-Moore biodegradable flushing solution. Do not overfill or tool will need to be recharged with air before back flush. Follow manufacturer's suggested procedures for proper handling of solution.

IMPORTANT: Do not substitute with any other solution. The flushing tool is designed to use only this concentrate. Use of any other solution can result in damage to the tool, cooler components, or improper flushing of the cooler.

3. Secure fill cap and pressurize the flusher can with shop air to 550-700 KPA (120 PSI).

CAUTION:

Shop air supply must be equipped with a water/oil filter and not exceed 825 KPA (120 PSI).

4. Connect the discharge hose to the transmission end of the oil cooler pipe that goes to the top fitting at the radiator.

5 Clip discharge hose onto the oil drain container.

6. Mount the flushing tool to the undercarriage of vehicle with the hook provided and connect the hose from the flushing tool to the remaining oil cooler pipe.

7. With the water valve on the tool in the off position, connect the waterhose from the water supply to the tool.

8. Turn on the water supply at the faucet.

Initial Flush

9. Switch the water valve on the tool to the on position and allow the water to flow through the oil cooler for 10 seconds to remove the supply of transmission fluid in the system.

CAUTION:

If water does not flow through the oil cooler (system is completely plugged) do not continue flushing procedure. Turn the water off immediately and inspect the pipes and cooler for restriction. Replace the oil pipe(s) and/or cooler according to the service manual.

10. Switch the water valve on the tool to the off position and clip the discharge hose onto a five gallon pail with a lid or position a shop towel over the end of the discharge hose to prevent splash. Discharge will foam vigorously when solution is introduced into water stream.

11. Switch the water valve on the tool to the "on" position and depress the trigger to mix flushing solution into the water flow. Use the bale clip provided on the handle to hold the trigger down.

12. Flush oil cooler with water and solution for two minutes. During this flush, attach the air supply to the air valve located on plumbing of tool, for 3 to 5 seconds at the end of every 15-20 second interval, to create a surging action.

CAUTION:

Shop air supply must be equipped with a water/oil filter and not exceed 825 KPA (120 PSI).

13. Release the trigger and switch the water valve on the tool to the "off" position.

14. Disconnect both hoses from the oil cooler pipes.

Backflush

15. Connect hoses to the oil cooler pipes opposite from the initialflush procedures to perform a backflush.

16. Repeat Steps 11 and 12.

17. Release the trigger and allow water only to rinse the oil cooler for one minute.

18. Switch the water valve on the tool to the "off" position, and turn the water supply off at the faucet.

19. Attach air supply to the air valve located on plumbing of tool and dry the system out with air for at least two minutes, or longer, if moisture is visible exiting from the oil cooler line discharge hose. Use an air chuck clip, if available, to secure the air chuck onto the air valve for ease of operation.

IMPORTANT: Excessive residual moisture can cause corrosion in the oil cooler or cooler pipes and can damage the transmission/transaxle. If Steps 20 through 23 cannot be completed at this time, rinse the oil cooler and cooler pipes with transmission fluid. Complete Steps 20 through 23 after reinstallation of transmission/transaxle.

20. Connect the cooler feed pipe to the transmission/transaxle (Refer to Table 1 on Page 4).

21. If not already connected, attach the discharge hose to the cooler return pipe and place into an appropriate drain container.

22. After filling the transmission/transaxle with automatic transmission fluid, start the engine and run for 30 seconds. This will remove any residual moisture from the oil cooler and cooler pipes. Protect all components from corrosion and check flow rate through the cooler. A minimum of two (2) quarts must be obtained during this 30 second run. If fluid flow is insufficient, check the fluid flow out of the transmission/transaxle by disconnecting the oil cooler feed line at the radiator and restarting the engine. Do the following according to flow rate:

Insufficient Feed Flow - Inspect the transmission/transaxle for cause.

Sufficient Feed Flow - Inspect oil cooler return pipe and fittings for restrictions or leaks. Repeat the check of fluid flow out the return line, and if flow is still inhibited, replace the oil cooler.

23. Remove discharge hose, reconnect cooler return pipe to transmission/transaxle, and refill unit to proper fluid level according to the service manual.

Table 1: Direction of fluid in oil cooler pipes at transmission/transaxle.

Top Connector is cooler feed Bottom connector, is cooler return 200/200C 200-4R

Vertical (top) connector is cooler feed Horizontal (bottom) connector is cooler return 440-T4

Top connector is cooler return Bottom connector is cooler feed 125/125C 250/250C 325/325-4L 350/350C

Tool Cleaning - Each Use

24. Disconnect the water supply hose from the tool.

25. Bleed air pressure from the can, remove fill cap, return any unused solution to the container, and rinse the can out with water. Do not store tool with solution in tank.

Tool Cleaning - Every Third Use

26. Loosen large coupling nut and remove plumbing from tank (Refer to Figure 1).

27. Remove screen from plumbing and wash with water.

28. Use the cleaning pin (Refer to Figure 1) to remove any material in the solution orifice. Orifice is located in plumbing below screen.

29. Reconnect plumbing and fill can half full with water, secure the fill cap, and pressurize the can to 550-700 KPA (80-100 PSI).

30. Aim tool into the five gallon pail or floor drain and depress the trigger to allow water from the can to flow through the solution orifice for 30 secords to ensure proper cleaning.

31. Bleed air pressure from can, remove the fill cap, and empty the can.

32. Reconnect fill cap on the flushing tool.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.