Thermal Vacuum Valve - Carb: Testing and Inspection

Fig. 17 Coolant temperature thermal switch test. Low temperature:

Fig. 18 Coolant temperature thermal switch test. High temperature:

1. Drain cooling system partially, and remove thermal switch from intake manifold.
2. Cool switch below 86°F (30°C). Using ohmmeter, check for continuity between terminals, Fig. 17.
3. Heat switch to over 116°F (46.5°C). Using ohmmeter, check that there is no continuity between terminals, Fig. 18.
4. Wrap sealing tape on threads and install switch in intake manifold.
5. Refill cooling system.