Connect the MS 554-07 instrument to it.
Warm up the engine, then stop it. Pressurize the system.
Stop pumping when the pressure is 0.1 bar below the opening pressure of the valve in the expansion tank plug.
The pressure must not drop. If this occurs, locate the leak.
Gradually unscrew the union of the tool MS 554-07 to relieve pressure in the cooling system, and then remove the tool MS 554-01 and reinstall the expansion tank plug valve with a new gasket.