Fasten tester to equalizing reservoir. Using manual pump, build up approx. 1 atmos (14.2 psig) pressure in coolant system. The coolant system has leaks if the pressure does not decrease after approx. 1 ÷ 2 minutes.
Fasten coolant plug and tester to connection piece. Build up pressure by means of manual pump. The opening pressure must correspond to the figure show the coolant plug.