Catalytic Converter: Service and Repair

CATALYTIC CONVERTER

REMOVAL

WARNING: THE NORMAL OPERATING TEMPERATURE OF THE EXHAUST SYSTEM IS VERY HIGH. THEREFORE, NEVER ATTEMPT TO SERVICE ANY PART OF THE EXHAUST SYSTEM UNTIL IT IS COOLED. SPECIAL CARE SHOULD BE TAKEN WHEN WORKING NEAR THE CATALYTIC CONVERTER. THE TEMPERATURE OF THE CONVERTER RISES TO A HIGH LEVEL AFTER A SHORT PERIOD OF ENGINE OPERATION TIME.

NOTE: Before replacing a catalytic converter, determine the root cause of failure. Most catalytic converter failures are caused by air, fuel or ignition problems. Refer to the appropriate service diagnostic information for repair procedures.

1. Remove muffler and intermediate pipe.





2. Disconnect downstream oxygen sensor electrical connector.





3. Remove catalytic converter to exhaust manifold attaching fasteners and remove converter from vehicle.
4. Remove and discard flange gasket.

NOTE: When replacement is required on any component of the exhaust system, original equipment parts (or equivalent) must be used.

INSPECTION

WARNING: THE NORMAL OPERATING TEMPERATURE OF THE EXHAUST SYSTEM IS VERY HIGH. THEREFORE, NEVER ATTEMPT TO SERVICE ANY PART OF THE EXHAUST SYSTEM UNTIL IT IS COOLED. SPECIAL CARE SHOULD BE TAKEN WHEN WORKING NEAR THE CATALYTIC CON- CONVERTER. THE TEMPERATURE OF THE CONVERTER RISES TO A HIGH LEVEL AFTER A SHORT PERIOD OF ENGINE OPERATION TIME.

Check catalytic converter for a flow restriction.
Visually inspect the catalytic converter element by using a borescope or equivalent. Remove oxygen sensor(s) and insert borescope. If borescope is not available, remove converter and inspect element using a flashlight. Inspect element for cracked or melted substrate.

NOTE: Before replacing a catalytic converter, determine the root cause of failure. Most catalytic convertor failures are caused by air, fuel or ignition problems. (Refer to Appropriate Diagnostic Information) for test procedures.

INSTALLATION

NOTE: When assembling exhaust system do not tighten clamps until all components are aligned and clearances are checked.

1. Assemble catalytic converter to exhaust manifold connection. Use a new flange gasket.
2. Tighten the catalytic converter to exhaust manifold fasteners to 28 Nm (250 inch lbs.).
3. Install intermediate pipe and muffler.
4. Working from the front of system; align each component to maintain position and proper clearance with underbody parts.
5. Tighten band clamps to 47 Nm (35 ft. lbs.).

CAUTION: Band clamps should never be tightened such that the two sides of the clamps are bottomed out against the center hourglass shaped center block. Once this occurs, the clamp has lost clamping force and must be replaced.

6. If removed, install downstream oxygen sensor.
7. Connect downstream oxygen sensor electrical connector.