Catalytic Converter Chevrolet Cavalier I

The catalytic converter is located in exhaust system in front of the muffler. It is a stainless steel, muffler shaped, device that reduces exhaust emissions by changing toxic gases into less harmful ones.

There are 2 types of catalytic converters: Conventional Oxidation Converters (COC) and Three-Way Converters (TWC). Catalytic converters may be one of 2 designs: a honeycomb-type block which is non-serviceable or small alumina beads that can be removed and replaced on some models.

Even though both converters contain a base material of alumina, COC is impregnated with platinum/palladium and TWC contains material coated with platinum/rhodium. While both converters reduce hydrocarbons (HC) and carbon monoxide (CO), TWC reduces oxides of nitrogen (NOx).

Note. Use only unleaded fuel on vehicles equipped with a catalytic converter. If leaded fuel is used, coating of catalytic surfaces will result. If this occurs, converter is useless and must be replaced.

On some models, a TWC is used in conjunction with a COC (fresh air is introduced between converters to aid in oxidation of gases), this is called a dual-bed converter. see scheme 1

On all other models, first converter (3-way) in exhaust system reduces hydrocarbons (HC) and carbon monoxide (CO), but mainly oxides of nitrogen (NOx). In second converter (oxidation type), with extra air from AIR pump, reduction of hydrocarbons (HC) and carbon monoxide (CO) takes place.

HEAT SHIELDS

Combustion reaction, which is furthered by converter, releases additional heat into exhaust system. Temperatures in catalytic converter can reach 1600°F (871°C) under normal conditions. Special heat shields are used to protect underbody and under-vehicle components from this extreme heat.

MAINTENANCE

There is no scheduled maintenance of a catalytic converter since it is designed to last lifetime of vehicle. If it does not perform correctly, replace it. On some vehicles, equipped with converters that are filled with catalyst coated beads, bead removal and replacement is possible.

Scheme 21

1. Remove bottom cover by making a shallow cut close to bottom outside edge. (Scheme 22) A shallow cut is required to avoid damage to inner shell. (Scheme 21): Removal of Catalytic Converter Bottom Cover Bottom cover can be replaced on General motors vehicles only.
2. Remove insulation and check inner shell for damage. If damage to inner shell is found, entire catalytic converter must be replaced.
3. 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.
4. 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.

Scheme 22

Scheme 23

1. Raise vehicle on hoist. Attach vacuum aspirator device (J-25077) to exhaust pipe. (Scheme 23) Attach air supply to air hose fitting on vacuum pump. Apply enough air pressure (minimum 80 psi) to hold catalytic beads in place. (Scheme 22): Attaching Vacuum Aspirator to Tailpipe
2. Drive a small chisel between fill plug and converter housing, making sure not to damage housing. Continue driving small chisel into plug until plug is deformed enough to be removed with pliers. CAUTION: DO NOT pry plug from converter housing or damage to housing may result.
3. Clamp vibrator and catalytic container onto converter. (Scheme 23) Disconnect air supply from vacuum aspirator and attach it to vibrator unit. Allow vibrator to operate for about 10 minutes to remove all catalytic beads. (Scheme 23): Installation of Vibrator & Catalytic Bead Container
4. When all catalytic material is removed, disconnect air supply and remove container from converter. Discard catalytic beads. Fill container with approved replacement catalytic beads. Install a fill tube fixture to vibrator device.
5. Attach air supply to both vibrator and aspirator. With container attached to fill tube, catalytic beads will begin to move into converter.
6. When catalytic beads stop flowing, disconnect air supply to vibrator and note level of beads. It should be even with fill plug. Add more beads if required. NOTE: If any beads exit through tailpipe during refilling of converter, converter is defective and must be replaced.
7. Apply a anti-seize compound to fill plug. Install plug and tighten. If equipped with a press type fill plug, install a "bridge-and-bolt" type service plug and tighten to 28 ft. lbs. (38 N.m).

COMPONENT TESTING

Note. Testing information not available.