No. 1 Valve (Exc. 626 & B2000)
Drain radiator and remove hoses from water thermo valve. Remove water thermo valve from bottom tank of radiator. Connect hoses to valve and place valve in container of water with thermometer. Gradually heat water and note temperature at which air will pass through valve. See Fig 1. If air does not pass through valve as shown in Thermo Valve/Switch Specifications table, replace No. 1 water thermo valve.