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Close-Coupled Converter Caution on Late Model GM Vehicles
Certain late model General Motors vehicles may be equipped with a new style of catalytic converter, technically known as the close-coupled catalytic converter.
This new style converter provides quick catalyst warm-up, resulting in lower tailpipe emissions earlier in operating cycle. If and engine failure (such as a broken intake/exhaust valve or
piston), debris may be deposited in the converter through engine exhaust ports.
If the engine failure is due to a severe overheating event, damage to the ceramic “brick” internal to the catalytic converter may occur. This could result in ceramic debris being drawn into the engine through the cylinder head exhaust ports.
If a replacement engine is installed in either of these instances, the replacement engine may fail due to the debris being drawn into the combustion chamber upon startup.
When installers replace an engine due to a failure of this type, the installer must inspect the converters and ALL transferred components such as the intake and exhaust manifolds. Remove any debris that is found. In cases where engine failures were as a result of severe overheating, installers should inspect each catalytic converter for signs of melting or cracking of the ceramic “brick”. If damage is observed, the converter should be replaced.
Some or all of the preceding technical information was provided by the
Automotive Parts Remanufacturers Association (APRA). For more
information on technical bulletins available through APRA call
703-968-2772 or visit www.AutoBulletins.com.