Causes for a compressor not able to produce air pressure efficiently -
▪ Greater bumping clearance
▪ Sluggish opening and closing of suction and delivery valves.
▪ Suction or delivery valves are leaking.
▪ Leakage through compressor piston rings.
▪ Leakage through cylinder head gasket
▪ Insufficient cooling water circulation
▪ Dirty or partially chocked suction air filter.
▪ Inlet temperature of the air to the L.P. stage is too high.
▪ Leakage of air from compressor parts and joints such as drain valve, pressure gauge