General Motors Corp. is recalling 750,000 cars that might stall from "catalytic converter plugging" -- a defect that could cause a substantial and sometimes sudden loss of engine power.
GM officials said yesterday that the voluntary recall affects 1981- and 1982-model Buicks, Oldsmobiles and Pontiacs equipped with V-8 engines.
A total of 3 million GM cars built for the 1981, 1982 and 1983 model years were equipped with the catalytic converters in question, a GM spokesman said. He said the converters were installed in about 90,000 of the 1983 models.
GM is monitoring the performance of the cars not involved in the current recall, the spokesman said.
The problem is with the dual-bed catalytic converter, usually located between the engine and the tail-pipe assembly of a car.
Catalytic converters change poisonous compounds in engine exhaust fumes into relatively harmless matter such as water vapor, carbon dioxide and nitrogen before the fumes move from the exhaust system into the atmosphere.
GM began putting the dual-bed units in its 1981 passenger models to meet more stringent Environmental Protection Agency requirements limiting poisonous carbon monoxide (CO) emissions from cars to 3.4 grams per mile (gpm). The previous CO standard was 7 gpm.
The dual-bed converters successfully reduce the CO emissions. But with certain engines, primarily V-8 and V-6 designs, the converters tend to self-destruct.
Ceramic pellets in the upper bed of the converter break up and fall through louvered openings into a narrow air chamber in the middle of the converter. The broken pellets then plug up the lower louvers, significantly retarding the flow of exhaust gas.
Increased exhaust system backpressure results from the blockage. That condition leads to a loss of engine power. A stricken car can only reach a maximum speed of about 30 miles per hour. In some cases, the car won't start.