Thermal Vacuum Valve

Mounted on intake manifold, thermal vacuum valve is connected between vacuum port in carburetor and EGR valve. Valve opens when coolant temperature reaches 115-129°F (46-54°C) on Pickup and Trooper II or 122°F (50°C) on Impulse. With valve closed, EGR system does not operate. As coolant warms, valve opens, allowing normal EGR operation.