For 1990-2009 cars

# ENGINE/TRANSMISSION OIL COOLER DIAGNOSIS

#### Models Affected: All

When radiator oil coolers are suspected of leaking, they should be thoroughly checked before the radiator is removed for repair. This can be done by testing the cooler with air pressure while the radiator is still in the car. BT-8316-A or J-34111 are Available Tools that can be used to test the oil coolers.

#### Testing

1. Allow the engine to cool down.

2. Disconnect the negative battery cable (s).

3. Remove the radiator cap. Check coolant level in the radiator and add as necessary.

#### CAUTION:

Never remove the radiator cap on a warm engine. Removing the cap immediately lowers the boiling point of the liquid and can cause violent overflow. The result could be a large coolant loss and possible personal injury.

4. Place a drain pan under the car to catch lost oil.

5. Disconnect the lower pipe or hose from the oil cooler to be tested. Install the correct plug from the Tool Kit into the open radiator fitting.

6. Disconnect the upper pipe or hose from the oil cooler. Install the correct adapter from the Tool Kit into the radiator oil cooler fitting.

7. Apply 345 kPa (50 psi) of air pressure at adapter valve.

8. Watch for bubbles in the coolant. If bubbles appear, remove radiator for repair.

9. If no bubbles appear, increase the air pressure to 690 kPa (100 psi) and watch for bubbles. If still no bubbles, increase the air pressure to 1,034 kPa (150 psi) and again watch for bubbles.

If no bubbles appeared, the oil cooler is not leaking. If bubbles did appear, remove the radiator for repair.

10. Reconnect the cooler lines (or hoses using new "O" rings) and torque to specifications.

11. Connect the negative battery cable(s).

12. Start the engine and check for leaks.

13. Check and add coolant, engine oil or transmission fluid as necessary.

#### Warranty Information

Engine Oil Cooler Diagnosis

Labor Operation: T0124 Labor Time: 0.5 hr (Diesel Engine Only) Failure Code: 92

Transmission Oil Cooler Diagnosis

Labor Operation: T0125 Labor Time: 0.4 hr (Gas or Diesel Engine) Failure Code: 92

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.