280 Models (Calif.)
- With engine at normal operating temperature, connect a CO meter to exhaust gas back-pressure line. Read and record exhaust gas CO value.
- Next, disconnect vacuum line from straight connection of the 122°F (50°C) thermo valve and connect it to straight connection of the 63°F (17°C) thermo valve. See Figure.
- Again check CO value of exhaust gas. System is functioning properly if CO value decreases from first reading. If not, check all vacuum lines and connections for damage and leaks and repair as necessary.
- If all vacuum lines and connections are okay, and the thermo valves are operating properly, replace diverter valve.