The catalytic converter first appeared in 1975 as standard equipment on vehicles. It was designed to significantly reduce harmful emissions and pollutants from the air. Many state auto emission control stations routinely check catalytic converters for proper installation and operation. Consisting of certain catalysts, the catalytic converter after-burns rich fuel vapors to reduce carbon monoxide, hydrocarbons and other air-polluting contaminants. Like all automotive components, the vehicle owner should be aware of the symptoms of a failing or inoperative catalytic converter.
Place the vehicle's transmission in park or neutral and set the emergency brake. Raise the vehicle with a floor jack and place two jack stands under the front part of the frame behind each wheel. Slide yourself under the vehicle and locate the catalytic converter, which will look like a metal canister about two feet long by one foot wide. Attach a quarter-inch drill bit to a drill and drill a hole in the exhaust pipe just behind the catalytic converter.
Start the engine. Firmly stick an exhaust pressure gauge probe into the drilled hole and read the scale on the gauge. Refer to the manufacturer's specification for the minimal amount of exhaust pressure required on your vehicle. For instance, if you read approximately 15 pounds of pressure or more, the catalytic converter functions properly, with no clogs. If the reading shows less than that, by 5 or more pounds, then the converter is clogged with soot and burned catalyst pellets. Gently tap an exhaust pipe plug into the drilled hole, using a hammer.
Drill a quarter-inch hole into the exhaust pipe just in front of the catalytic converter. Start the engine and stick the exhaust gas pressure gauge probe into the drilled hole. Read the scale. If you have a high or normal reading (according to specifications) you have verified that normal exhaust gas flows into the inlet side of the catalytic converter. Remember: a high reading at the front will be normal, but a low reading at the rear of the catalytic converter will indicate a clogged converter. Hammer a small exhaust pipe plug into the front drill hole.
Visually inspect the catalytic converter while under the car. Any type of rainbow color on the bottom of the converter (underneath the heat shield) will indicate extremely high temperatures where the converter body has become red-hot. Look for any cracks in the converter body or loose exhaust pipe clamps.
Smell the catalytic converter after the vehicle has reached normal operating temperature. Any sulphur or rotten egg odor will indicate the chemically coated pellets inside the converter have melted. Using a rag over your hand, pound on the converter body with the heel of your hand. A rattling sound will be normal, meaning the pellets have not melted and fused together. No sound will indicate a melted interior.
