mercury Workshop Repair Guides

Mercury Workshop Service and Repair Manuals

Vacuum Check Valve, AIR|Description and Operation|Page 1400 > < Thermal Vacuum Valve, Air Injection|Description and Operation|Page 1396
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Vacuum Check Valve: Description and Operation

Fig.86 - Thermactor Vacuum Vent Valve

Fig.87 - Thermactor Vacuum Vent Valve Schematic

DESCRIPTION

This valve, Figs. 86 and 87, is used on some 1978-82 engines equipped with variable venturi carburetor. It provides the air for the thermactor
retard delay valve and air bypass valve during idle modes to deactivate the thermactor system after a controlled period of time. 

Application of vacuum from the carburetor to both ports of the thermactor vacuum vent causes the dump valve to seat and vacuum to be applied to
the rest of the system. Removal of vacuum during idle modes results in unseating of the dump valve, opening of the vent and allowing air to enter
the system to reduce the vacuum previously applied to the retard delay valve.

Vacuum Check Valve, AIR|Description and Operation|Page 1400 > < Thermal Vacuum Valve, Air Injection|Description and Operation|Page 1396