To check the condition of the thermal valve, disconnect the hose 1 (see photo), going to the vacuum regulator of the ignition distributor, disconnect hose 2 from the tee and blow into this hose. At a coolant temperature of 13±3°C, the valve must be open. It should close at a temperature of 20±3°C.
At installation of the valve add cooling liquid to norm.
Warning. Use only black thermal valves marked PE 20210 (Pierburg APG) or 51 AA 11.