Troubleshooting the automatic transmission is simplified by using the proven method of diagnosis. One of the most important things to remember is that there is a definite procedure to follow. Do not take short cuts or assume that critical checks or adjustments have already been made.

The following procedures are recommended for checking and/or verifying that the various components are adjusted and operating properly. Use Rotunda Automatic Transmission Tester 014-00737 or equivalent. Follow the manufacturer's instructions.

Transmission Fluid Leakage Checks

Check the speedometer cable connection at the transmission. Replace the rubber seal, if necessary.

Check for leakage at oil pan gasket.

NOTE: Fluid from other external sources can collect between the case and pan rail and give the appearance of a pan gasket leak. If fluid is present check the following positions as outlined.

Oil Pan

Leakage at the oil pan gasket often can be stopped by tightening the retaining bolts to 8-13.5 Nm (71-119 lb-in). Do not over-tighten pan bolts. If necessary, replace the gasket.

Fluid Filler Tube

Check the fluid filler tube connection at the transmission case or oil pan. If leakage is found here, install a new O-ring and press the filler tube to the case. The filler tube bracket should align properly and be attached to the transmission or engine.

Transmission Cooler Lines

 CAUTION: Do not try to stop the fluid leak by increasing the torque beyond specification. This may cause damage to the case threads.

Check the fluid lines and fittings between the transmission and the cooler in the radiator tank for looseness, wear or damage. When fluid is found to be leaking between the case and the cooler line fitting, tighten the fitting to 31 Nm (23 lb-ft).

If the leak continues, replace the cooler line fitting and tighten to 24-31 Nm (18-23 lb-ft). The same procedure should be followed for fluid leaks between the radiator cooler and cooler line fittings.

Transmission Case

Check the engine coolant in the radiator. If transmission fluid is present in the coolant, the transmission cooler in the radiator is probably leaking.

The cooler can be further checked for leaks by disconnecting the lines from the cooler fittings and applying 345-517 kPa (50-75 psi) air pressure to the fittings. Remove the radiator pressure cap to relieve the pressure buildup at the exterior of the oil cooler tank. If the cooler is leaking and/or will not hold pressure, the cooler must be replaced. Refer to Section 03-03 for coolant replacement procedure.

If leakage is found at either the throttle valve lever shaft or the manual lever shaft, replace either or both seals.

Pipe Plugs

The automatic overdrive transmission (AOD) has four pipe plugs: three on the RH side of the case and one on the LH side. Inspect the plugs for leakage. Ensure they are tightened to 8-16 Nm (6-12 lb-ft). If tightening does not stop the leak, replace the plug.

When a converter drain plug leaks, remove the drain plug with a six-point wrench. Coat the threads with Pipe Sealant with Teflon® D8AZ-19554-A (ESG-M4G194-A and ESR-M18P7-A) or equivalent and install plug. Tighten the drain plug to 11-38 Nm (8-28 lb-ft). Fluid leakage from the converter housing may also be caused by engine oil leaking past the rear main bearing seal, or from oil galley plugs. Verify the exact cause of the leak before starting service procedures.

Oil soluble aniline or fluorescent dyes premixed at the rate of 2.5ml (1/2-teaspoon) of dye powder to 0.23l (1/2-pint) of transmission fluid have proved helpful in locating the source of fluid leakage. Such dyes may be used to determine whether an engine oil or transmission fluid leak is present, or if the fluid in the oil cooler leaks into the engine coolant system. A black light must be used with the fluorescent dye solution.

Fluid Leakage in Converter Area

In diagnosing and correcting fluid leaks in the front pump and converter area, use the following procedures to locate the exact cause of the leakage. Leakage at the front of transmission, as evidenced by fluid around the converter housing, may have several sources. By careful observation, it is possible, in many instances, to pinpoint the source of leak before removing the transmission from the vehicle. The paths which the fluid takes to reach the bottom of the converter housing are shown in the following illustration.

1. Fluid leaking by the front pump seal lip will tend to move along the impeller hub and onto the back of the impeller housing. Except in the case of a total seal failure, fluid leakage by the lip of the seal will be deposited on the inside of the converter housing only, near the outside diameter of the housing.

2. Fluid leakage by the outside diameter of the seal and front pump body will follow the same path which the leaks by the front pump seal follow.

3. Fluid that leaks by a front pump to case bolt will be deposited on the inside of the converter housing only. Fluid will not be deposited on the back of the converter.

4. Fluid leakage from the converter drain plugs or converter-to-flywheel stud weld, will appear at the outside diameter of the converter on the back face of the flywheel, and in the converter housing only near the flywheel. Fluid leaks from the torque converter will leave a ring of fluid around the inside of the transmission converter housing.

   NOTE: White tissue paper may aid in determining the color (red is transmission fluid) and source of the leaking fluid.

5. Engine oil leaks are sometimes improperly diagnosed as transmission front pump seal leaks. The following areas of possible leakage should also be checked to determine if engine oil leakage is causing the concern.
   1. Leakage at the rocker arm cover may allow oil to flow over the converter housing or seep down between the converter housing and cylinder block causing oil to be present in or at the bottom of the converter housing.
   2. Oil galley plug leaks will allow oil to flow down the rear face of the block to the bottom of the converter housing.
   3. Leakage at the crankshaft seal will work back to the flywheel, and then into the converter housing.
   4. Leakage at engine oil pressure sender.

6. Fluid leakage from other areas, such as the power steering system forward of the transmission, could cause fluid to be present around the converter housing due to blowback or road draft. The following procedures should be used to determine the cause of the leakage before service.
   1. Remove the transmission dipstick and note the color of the fluid. Original factory fill fluid is dyed red to aid in determining if leakage is from the engine or transmission. Unless a considerable amount of makeup fluid has been added or the fluid has been changed, the red color should assist in pinpointing the leak. However, a power steering leak may be mistaken for a transmission leak since the fluid color for both looks the same. Observe the power steering system for leaks that could be misidentified as a transmission leak.
   2. Remove the converter housing cover. Clean off any fluid from the top and bottom of the converter housing, front of the transmission case and rear face of the engine and engine oil pan. Clean the converter area by washing with a suitable non-flammable solvent and blow dry with compressed air.
   3. Wash out the converter housing, the front of the flywheel and the converter drain plug. The converter housing may be washed out using cleaning solvent in a squirt-type oil can. Blow all washed areas dry with compressed air.
   4. Start and run the engine until the transmission reaches its normal operating temperature. Observe the back of the block and top of the converter housing for evidence of fluid leakage. Raise the vehicle on a hoist. Refer to Section 00-02. Run the engine at fast idle, then at engine idle, occasionally shifting to the DRIVE and REVERSE ranges to increase pressure within the transmission. Observe the front of the flywheel, back of the block (in as far as possible), and inside the converter housing and front of the transmission case. Run the engine until fluid leakage is evident and the probable source of leakage can be determined.

Converter Leakage Check

Tools Required:

• Rotunda Torque Converter Leak Detector 021-00054

If welds on the torque converter indicate leakage remove the converter and make the following check:

Assemble Rotunda Torque Converter Leak Detector 021-00054 or equivalent to the converter. Test the converter for leaks, following the directions supplied with the detector kit.