Catalytic Converter: Testing and Inspection

Proper diagnosis for a restricted exhaust system is essential before any components are replaced. The following procedures may be used for diagnosis, depending upon engine or tool used:

Exhaust System Check:

CHECK AT A.I.R. PIPE:

1. Remove the rubber hose at the exhaust manifold A.I.R. pipe check valve. Remove check valve.
2. Connect a fuel pump pressure gauge to a hose and nipple from a Propane Enrichment Device.
3. Insert the nipple into the exhaust manifold A.I.R. pipe.


CHECK AT 02 SENSOR:

1. Carefully remove O2 sensor.
2. Install Exhaust Backpressure Tester in place of 02 sensor.
3. After completing test described below, be sure to coat threads of 02 sensor with antiseize compound prior to re-installation.


DIAGNOSIS:

1. With the engine at normal operating temperature and running at 2500 rpm, observe the exhaust system backpressure reading on the gauge.

2. If the backpressure exceeds 1-1/4 psi (8.62 kPa), a restricted exhaust system is indicated.

3. Inspect the entire exhaust system for a collapsed pipe, heat distress, or possible internal muffler failure.

4. If there are no obvious reasons for the excessive backpressure, a restricted catalytic converter should be suspected, and replaced.