Operation CHARM: Car repair manuals for everyone.

Catalytic Converter: Description and Operation

PURPOSE
The catalytic converter reduces the emission of Hydrocarbons, Carbon Monoxide and Oxides of Nitrogen.

OPERATION
The catalytic converter remains unchanged while enabling a chemical reaction to take place which combines Hydrocarbons (HC) and Carbon Monoxide (CO) with Oxygen to form water (H2O) and Carbon Dioxide (CO2).

Fig. 13 - Underfloor Converter:






On 1975-79 vehicles, the catalyst is structured in the form of pellets--Fig 13.

Fig. 14 - Monolith Converter:






On 1980-82 vehicles, two converters are used, the underfloor converter--Fig 13 and a honeycomb monolith converter--Fig 14.

The catalyst consists of a porous substrate of an inert material, coated with platinum and other noble metals--active catalytic materials.

Due to its high operating temperatures, the underfloor converter--located in the exhaust system between the exhaust manifold and muffler--requires heat shields to protect chassis components, passenger compartment and other areas from heat related damage.

Fig. 15 - Fuel Tank Filler Safety Neck For All Vehicles Equipped With Catalytic Converters:






A smaller diameter fuel filler neck prevents system contamination by not allowing the larger diameter leaded fuel nozzles to be inserted--Fig 15.

CAUTION: Use unleaded fuels only. Use of more than a very small amount of leaded fuel will ruin catalyst.

NOTE: Periodic maintenance of the exhaust system is not required; however, if the vehicle is raised for other service, it is advisable to check the general condition of the catalytic converter.