GEAR (64 teeth) 5C3716 - Caterpillar

Symptom
Oil is leaking from the air compressor.Probable Cause
Damaged seal or missing seal for mounting the compressorCheck the torque of the bolts that mount the air compressor to the engine. Replace the seal that is between the mounting flange of the air compressor and the engine. Tighten the bolts to the standard torque.
Damaged rear coverCheck the rear cover on air compressors that do not have a rear accessory. Check for cracks in the rear cover. Check the torque of the bolts that mount the rear cover.
Damaged rear cover sealCheck the torque of the bolts that mount the rear drive. Replace the seal that is between the mounting flange of the air compressor and the accessory. Tighten the bolts to the standard torque.
Cracked crankcase or rear coverInspect the exterior of the air compressor for components that are cracked or broken. Mounting bolts that are loose may cause the crankcase to crack. A cracked crankcase cover can be caused by using too much torque to tighten fittings that connect to the crankcase. Replace the air compressor if the crankcase is cracked.
The rear cover is loose.Check the rear cap bolts. Tighten the bolts, if necessary.
Leaking oil supply line or fittingsCheck that all fittings are tightened to standard torque. Tighten the fittings, if necessary. Check the oil line for damage. Replace the oil line, if necessary.
The casting of the air compressor is porous.Replace the air compressor if porosity is found.
The O-ring for the end cover is missing or damaged.Replace the O-ring, if necessary.