F 350 2WD Pickup V8-351 5.8L (1983)
Vacuum Vent Valve: Testing and Inspection
1.
Disconnect vacuum hose from the servo that leads to the dump valve.
2.
Connect a hand vacuum pump to the hose, and draw vacuum. If vacuum cannot be obtained, the hose or dump valve is leaking, and should be
replaced.
3.
Step on brake pedal. The vacuum should be released. If not, adjust or replace the dump valve.
2.5 inches of Hg is minimum vacuum for normal
servo operation. The vacuum source is a hose attached to a 5/16 inch engine vacuum fitting port on all except 6.9 diesel. On the 6.9 diesel,
the vacuum source is the vacuum reservoir ``Vac'' port.
