LOCK 1S3513 - Caterpillar

Symptom
The air compressor passes excessive oil. Excessive oil is found in discharge lines. Excessive oil is found at exhaust valves of air system components.Probable Cause
Restricted air inletCheck the engine air cleaner and replace the air cleaner element, if necessary. Check the inlet line of the air compressor for restrictions and sharp bends.Verify that the air inlet line is the correct size. The minimum size of the air inlet line is 25.4 mm (1.00 inch) inside diameter for naturally aspirated installations.The maximum value for restriction is 635 mm (25.0 inches) of water.
Restricted oil return to engineThe oil return to the engine should not be restricted. Check the oil drain passages in the mounting flange of the air compressor for plugging.
Contaminants are not being drained from air system reservoirs.Check the reservoir drain valves for proper operation. A vehicle should be equipped with drain valves that are automatic, or all the reservoirs should be drained daily. It is best for the vehicle to have an air dryer with a desiccant cartridge.
Excessive engine oil pressureCheck the engine oil pressure with a test gauge and compare the value to the engine specification. When the oil pressure is too high, the oil level in the crankcase of the air compressor may be too high. The oil may not drain into the engine at the same rate as the oil is being pumped into the air compressor.
The air compressor is too hot.Remove accumulated debris from the exterior of the air compressor.Check the connections of the coolant lines.The nominal temperature of the coolant at the inlet port is 95 °C (203 °F).The minimum flow of the coolant for the air compressor at the speed of 2000 RPM is 6 L (1.6 US gal) per minute.
The air compressor is operating under load excessively.The pressure drop per minute from the air system of the vehicle should not exceed 7 kPa (1.0 psi) when the brakes are not applied. The pressure drop per minute should not exceed 20 kPa (3.0 psi) when the brakes are applied.
Poorly filtered inlet airCheck for a damaged air cleaner or dirty air cleaner. Check for damaged air inlet components or leaking air inlet components. Check the air piping and fittings.