Vacuum Delay Valve

Disconnect and remove No. 1 relief valve vacuum delay valve. Connect vacuum gauge to air control valve side of delay valve. Using an additional piece of tubing, connect delay valve directly to intake manifold vacuum. See Fig 1 .

Fig 1: Testing Vacuum Delay Valve Arrow on valve points toward No. 1 water thermo valve.
Start engine and operate at idle speed. Note reading on vacuum gauge at idle. Disconnect manifold vacuum from delay valve. Record time required for vacuum gauge to drop 11.8 in. Hg from reading recorded at idle.
If time is not within specifications, replace vacuum delay valve. No. 2 relief valve delay valve is tested in the same manner. See VACUUM DELAY VALVE SPECIFICATIONS table.

NOTE: If vacuum delay valve is stamped with an arrow, install with arrow facing intake manifold vacuum source.