Diagnosis is made by observing the amount of leakage that is indicated on the cylinder leakage gauge and by listening for leakage at various points of the cars system. JIFETOR Cylinder Leak Down Tester Kit, Professional Dual Pressure Gauges Engine Compression Leakdown Detector Leakage Test Set for Gasoline Engine with 10 12 14mm Spark Plugs on Car Truck Motorcycle.