The catalytic converter(s) is installed in the exhaust system in front of the muffler so that all exhaust gases must pass through it. The converter is a stainless steel, muffler shaped, device that reduces exhaust emissions.
There are 2 types of catalytic converters, oxidation and 3-way converters. The oxidation type converter contains material that is coated with platinum and palladium. This catalyst reduces hydrocarbons (HC) and carbon monoxide (CO).
The 3-way converters contain material coated with platinum, palladium and rhodium. This catalyst reduces hydrocarbons (HC), carbon monoxide (CO) and oxides of nitrogen (NOx).
The catalyst may be one of 2 types: a honeycomb-type block that is non-serviceable, or small ceramic beads that can be removed and replaced on some models.
Use only unleaded fuel on vehicles equipped with a catalytic converter. If leaded fuel is used, the Tetra Ethyl Lead in the fuel will coat the palladium, platinum and rhodium. If this coating effect takes place, the converter is useless. If this happens, the converter must be replaced.
The 3-way catalytic converter is used in conjunction with the conventional oxidation catalytic converter. All models with the oxygen sensor/feedback carburetor system use this type of converter. A 3-way converter in the exhaust system reduces hydrocarbons (HC) and carbon monoxide (CO), but mainly oxides of nitrogen (NOx). Oxidation type converters reduces, with extra air from the air pump, hydrocarbons (HC) and carbon monoxide (CO) only. General Motors uses only 1 converter in each system.
HEAT SHIELDS
The combustion reaction, which is furthered by the converter, releases additional heat into the exhaust system. Temperatures in the catalytic converter can reach 1600°F (871°C) under normal conditions.
Special heat shields are used to protect the underbody and under-vehicle components from this extreme heat.
MAINTENANCE
There is no scheduled maintenance of the catalytic converter since it is designed to last the lifetime of the vehicle.
Scheme 49
- Remove bottom cover by making a shallow cut close to the bottom outside edge. (Scheme 49) A shallow cut is required to avoid damage to inner shell. (Scheme 49): Removal of Catalytic Converter Bottom Cover Bottom cover can be replaced on General Motors vehicles only.
- Remove insulation and check inner shell for damage. If damage to inner shell is found, the entire catalytic converter must be replaced.
- If no damage is found, position new insulation into replacement cover. Apply a heat resistant sealer around edge of cover, using extra sealer at front and rear of pipe openings.
- Install replacement cover on converter and position retaining channel along edges. Complete installation by attaching clamps, provided with replacement cover, to both ends of converter.
COMPONENT TESTING
Note. Testing information not available.