The inlet valve plunger is damaged.

Replace any faulty parts.

There are intake cavity restrictions.

Remove the restrictions. Clean the cavity.

The governor is malfunctioning.

Overhaul or replace the governor. Refer to Air Compressor Governor Valve Replacement .

The unloader line or the cavity to the governor is restricted.

Remove the restriction.

The unloader mechanism is binding or sticking.

Overhaul or replace the cylinder head assembly. Refer to Air Compressor Overhaul .

There is a restriction in the cylinder head or in the compressor.

Remove the restriction or clean the cylinder head and the discharge line.

The bearings are worn or burned out.

Replace the bearings.

The air compressor is not getting the proper lubrication.

Check the engine lubrication system and the oil supply hose. Repair or replace as necessary.

The air compressor is excessively worn.

Replace the air compressor. Refer to Air Compressor Replacement .

There is a restriction in the air compressor cylinder head intake cavities, the discharge cavities or in the discharge pipe.

Remove the restriction or clean the components.

There are leaking or broken discharge valves.

Replace the cylinder head assembly.

The air compressor is excessively worn.

Overhaul or replace the air compressor. Refer to Air Compressor Overhaul or Air Compressor Replacement .

The inlet valve is stuck open.

Replace the cylinder head assembly.

The inlet valves are worn.

Replace the cylinder head assembly.

There is excessive leakage in the system.

Check the system and repair as needed.

The governor is out of adjustment.

Adjust the governor. Refer to Air Compressor Governor Valve Adjustment .

The governor leaks.

Overhaul or replace the governor. Refer to Air Compressor Governor Valve Replacement .

The air compressor leaks.

Check the fittings, the bolts and the mating surfaces. Tighten or repair as needed.

The unloader is not functioning.

Overhaul the cylinder head assembly.

The governor is faulty.

Overhaul or replace the governor. Refer to Air Compressor Governor Valve Replacement or Air Compressor Overhaul .

The air compressor is excessively worn.

Repair or replace the air compressor. Refer to Air Compressor Replacement .

The vacuum inlet is high.

Clean or repair the air compressor as necessary. Refer to Air Compressor Replacement .

The oil return line is small.

Install the proper size line.

There is excessive oil pressure.

Determine the cause of the condition and repair the condition.

The oil supply line to the air compressor is flooded.

Determine the cause of the condition. Repair the condition.

The oil seal rings in the crankcase cover are damaged.

Replace the seals.

The piston ring is not properly installed.

Install the piston ring properly.

There is back pressure from the engine crankcase.

Determine the cause of the pressure and repair the cause of the pressure.