TONG AS 2797379 - Caterpillar

Do not check for leaks with your hands. Pin hole (very small) leaks can result in a high velocity oil stream that will be invisible close to the hose. This oil can penetrate the skin and cause personal injury. Use cardboard or paper to locate pin hole leaks.
Check all oil lines and the connections for damage and for leaks.
Check the pump and the connections for damage and for leaks.
Follow the pump lines to the tank and valves. Check the lines for damage and leaks.
Check the oil tank for damage and leaks.
Check the tank oil level.
While the engine is running, use the oil sampling valve to get an oil sample. The oil sampling valve is located on the steering solenoid and relief valve. Check for air bubbles in the oil sample.
Remove the filter elements. Check for particles that were removed from the oil by the filter elements. A magnet will separate ferrous particles from nonferrous particles (piston rings, O-rings, or seals).