For 1990-2009 cars

# DIAGNOSING TRANSMISSION OIL LEAKS - THM 700R4

"This bulletin replaces Service Bulletin 83-I-99, Section 7 of 07/83 Diagnosing Transmission Oil Leaks - THM 700-R4."

To diagnose a transmission oil leak properly the following procedure should be used.

DIAGNOSIS PROCEDURE

The following procedure is performed on car:

1. Clean all residual oil from the transmission (C.R.C.'s electramotive cleanser, or equivalent is recommended). Repeat cleaning process until all residual oil is removed.

2. Dust the entire transmission with a white powder (eg., leak tracing powder or spray foot powder). If residual oil is left on the transmission, it will necessitate the cleaning and dusting procedure be repeated.

3. After normal operating temperture (170 DEG F) has been obtained, let the transmission stand for at least thirty (30) minutes (engine off).

4. Inspect the transmission for leakage by following red oil traces left in the powder.

5. Once the leak has been diagnosed as to location and type (wetness, moist, damp, etc.), refer to the following repair procedure:

#### IMPORTANT: Steps 1-4 should be used when diagnosing any transmission for an oil leak.

6. Repeat Steps 1-4 following repair of suspect leak source.

#### REPAIR PROCEDURE:

POSSIBLE LEAK POINT FIG- ------------------- URE ITEM NO. NO. PART NAME LEAK CAUSE CORRECTION --- ---- --------- ---------- -----------

1 1 Transmission Oil Pan Low Bolt Torque Retorque & Recheck Bolts Gasket Leak Replace Gasket

1 2 Case Porosity Repair Per Service Manual Cracked Replace Case

1 3 Cooler Fittings Low Torque Reseal & Retorque or Pressure Plugs

1 4 T.V. Cable Connector Cocked & Remove Connector & Connector Interfering With Reinstall Mount Seal Damaged Replace Seal Connector Cracked Replace Connector Cable

1 5 Servo Cover Porosity Replace (See Figure 2) 2 1 & 2 "O" Ring Damage Replace (See Figure 2)

1 6 Fill Tube Seal Missing or Remove Fill Tube & Replace Damaged Seal Tube Bent Above Replace Tube Transmission

1 7 Converter Seal Seal Damaged Replace Seal 3 - Seal Blown Out (See Figure 3) Check For Oversized Seal Bore or Restricted Drainback Passage.

1 8 Pump Assembly Pump Bolts Loose Retorque & Recheck Pump To Case Ring Replace Ring & Recheck. Cut or Damaged If Leak Persists, Replace Oil Pump Body With Part Number 8642986 or Repair (See Figure 3). 3 - Pump Porosity Replace Oil Pump Body Part Number 8642986.

1 9 Converter Assembly Hub or Seam Weld Replace Converter.

1 10 Vent Leaking Check for Oil Overfill & Correct As Necessary

11 Electrical Connector "O" Ring Missing Remove Connector & Replace Or Damaged "O" Ring Connector Damaged Replace Connector

1 12 Manual Shaft Seal Assembly Replace Seal Damaged

1 13 Governor Cover Gaps in Sealant Reseal with Loctite 1 14 Speedo Fitting Low Bolt Torque Retorque & Recheck Seal Damaged Replace Seal

1 15 Rear Extension Porosity Repair Per Service Manual Cracked Replace Low Bolt Torque Retorque & Recheck Extension to Case Replace Seal Seal Damaged Extension Seal Replace Seal Assembly Torn Or Damaged

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.