GM Service Manual Online
For 1990-2009 cars only

The torque converter is serviced as an assembly and should be replaced if any of the following conditions exist:

    â€¢ Metal particles found when flushing cooler or converter pipes--Converter flushing is not recommended. Refer to Transmission Fluid Cooler Flushing and Flow Test.
    â€¢ Oil pump damaged
    â€¢ Leaking converter welds
    â€¢ Converter pilot broken, damaged or poor fit in crankshaft
    â€¢ Converter hub scored or damaged
    â€¢ Internal damage to stator
    â€¢ Transmission fluid contaminated with coolant
    â€¢ Excess end play

The Torque Converter Should Not be Replaced If:

    â€¢ The transmission fluid has an odor, discoloration or no evidence of metallic of clutch plate material has been found. If any of these conditions apply:
       - Drain as much fluid as possible from the torque converter.
       - Replace the oil filter and pan gasket.
       - Fill transmission with the correct fluid, to the recommended level. See Section 7D4 On-Vehicle Servicing, Transmission Fluid Check for more specific information.
    â€¢ Any converter bolt hole threads are damaged or stripped.
        If either of these instances are found to exist, install thread inserts.