Posted on March 2, 2019 A New Method To Clean And Polish Engine Valve Stems A special 6V2033 Flap-type Finishing Brush is now available to clean and polish (make smooth) engine valve stems. Formerly, solvent or vibratory cleaning were used on valve stems. The 6V2033 Brush is 8″ (203 mm) in diameter and 2″ (51 mm) wide. It is made of a fine grade abrasive that will not damage the valve stems. To operate the brush, you need a bench grinder with a speed of 1800 to 3200 rpm (maximum). To fit the brush on the grinder, use two 6V2032 Adapters. If the grinder shaft is larger than .50″ (12.7 mm), the holes in the adapters can be made larger. For instructions to use the brush and for information on different methods to clean valves, see Form SEBF8002-01 Guidelines For Reusable Parts-Valves and Valve Springs. The 6V2033 Brush can be used to clean and polish all Caterpillar inlet and exhaust valve stems.