Idle Vacuum Valve
- Remove idle vacuum valve from connector on by-pass valve. Install a vacuum hose on small nipple of the valve and connect it to a 3-way tee. Connect another leg of the tee to a vacuum gauge, and the remaining tee fitting to the by-pass valve.
- Connect a vacuum gauge to intake manifold. See Fig 1. Start and warm engine to normal operating temperature.
- With engine at idle and transmission in neutral, disconnect large hose from large diameter port of idle vacuum valve.
- Using an external vacuum source, apply 3.5-4.0 in. Hg to large port of valve. Vacuum on gauge at by-pass valve should increase to within 3 in. Hg of intake manifold vacuum. If not, replace idle vacuum valve.
- Remove external vacuum source. Vacuum gauge reading should drop to 1 in. Hg or less. If not, replace idle vacuum valve.
Courtesy of FORD MOTOR CO.