Constant Vacuum Valve
- Disconnect hose No. 30 from the frequency solenoid valve B and connect a vacuum gauge to hose.
- Start engine and allow to run at idle speed. Reading after vacuum stabilizes should be 4-8 in. Hg vacuum. If vacuum is within range, constant vacuum valve is okay. Reconnect hose to frequency valve B. If vacuum stabilizes above or below specified range, replace constant vacuum valve.