DIAGNOSING TRANSMISSION OIL LEAKS - THM 700R4

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 (e.g. 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 temperature (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. ITEM NO. NO. PART NAME LEAK CAUSE CORRECTION

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

1 2 Case Porosity - Repair Per Service Manual

Cracked - Replace Case

1 3 Cooler Fittings Or Low Torque - Reseal & Retorque Pressure Plugs - Recheck

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

1 5 Servo Cover Porosity - Replace (See Fig 2) 2 1 "O" Ring Damaged - Replace (See Fig 2)

2 2

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

1 7 Converter Seal Seal Damaged - Replace Seal 3 - Seal Blown out - (See Fig 3) Check Seal Leak for Oversized Seal (Not Damaged) Bore or Restricted Drainback Passage

1 8 Pump Assembly Pump Bolts Loose - Retorque & Recheck Pump to Case Ring - Remove & Replace Cut or Damaged Ring (Recheck. If Leak Persists Re- place Oil Pump Body With P/N 8642986) or Repair (See Fig 3) 3 Pump Porosity - Replace Pump Body P/N 8642986

1 1 Converter Assembly Hub or Seam Weld - Replace Converter Leak

1 10 Vent Leaking - Check for Oil Over- fill & Correct as Necessary

1 11 Electrical Connector "O" Ring Missing - Remove Connector or Damaged and Replace Seal Connector Missing - Remove & Replace or Damaged Conn.

1 12 Manual Shaft Seal Assembly - Remove & Replace Damaged Seal

1 13 Governor Cover Gaps in Sealant - Reseal (Loctite or R.T.V.) - Remove & Replace

1 14 Speed Fitting Low Bolt Torque - Retorque Bolt & Recheck Seal Damage - Remove & Replace

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