The thermo valve is installed into the EGR vacuum supply line and is threaded into the intake manifold. The valve functions as a temperature switch to stop the vacuum signal to the EGR valve.
See Figure 1
- Connect a hand vacuum pump to the thermo valve nipple.
- Apply a vacuum with a hand vacuum pump.
- At coolant temperatures below 122°deg;F (50°deg;C), the vacuum should not hold.
- At coolant temperatures above 176°deg;F (80°deg;C), the vacuum should hold.
- Replace the thermo valve if not functioning properly.