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Home >> Ford >> 1978 >> Fiesta >> Repair and Diagnosis >> Engine Mechanical >> Auxiliary Emission Control Systems >> THERMACTOR I System >> Operation >> Exhaust Check Valve

Exhaust Check Valve

The exhaust check valve(s) allows thermactor air to enter the exhaust manifold port drillings (and converter on models with three-way catalyst), but prevents the reverse flow of exhaust gases in the event of improper operation of system components. The valve is located between by-pass valve and exhaust port drillings. Models equipped with a by-pass/diverter type valve also have a check valve located between the valve and the catalytic converter.