S I N G L E C Y L I N D E RA I R C O M P R E S S O RTM 5-3805-258-24-1T E S T I N G A N D A D J U S T I N GTESTING AND ADJUSTINGThe air pressure gauge will show low air pressurein the system when air system checks or tests areneeded. Air system checks are needed if the needlein the air pressure gauge keeps moving when thecomponents in the air system are not being used.AIR SYSTEM SCHEMATIC1. Air line between tank and air compressor. 2. Head for aircompressor. 3. Inlet air line from engine manifold. 4. Airgovernor. 5. Air tank.The complete air system, including the com-ponents in the air system, must be checked for anyair leaks. The air lines must have no breaks and allof the air line connections must be tight and haveno air leaks. If all of the air leaks have beenstopped and the air pressure gauge still has indi-cations of low air pressure further tests are needed.TYPICALAIR COMPRESSORINSTALLATION1. Air line between tank and air compressor. 2. Head on aircom~eaaor. 3. Inlet air line from anginemanifold. 4. Air@vernor. 6.. Coverover unloader valve. 7. AdjustmentScrew.Stop the engine and let all of the air out of thetank (5) and the air system. Disconnect line (1)from the cylinder head (2) to the air tank.4 - 81Start the engine and let it run for a minute. Withthe engine running hold a white card approxi-mately 2 in. (50.8 mm) from the opening in thehead (2), where air line (1) was disconnected butfor no more than 10 seconds. A large area of oil onthe card is an indication of wear either in the boreof the liner or the piston rings (and piston). A littleoil in fine drops is an indication of correct lubri-cation. If the card test shows no wear, connect airline (1) and let the air compressor fill the air tankuntil the air pressure gauge will not indicate anymore pressure.Run the engine at low idle speed and disconnectair inlet line (3) from the cylinder head (2). Withthe engine still running slow, hold, your hand closeto the opening in head (2) where air line (3) wasdisconnected. If air can be felt coming from theopening when the piston of the air compressor ison the compression stroke, the inlet valve is notclosing. Either the unloader valve under cover (6) isholding the inlet valve open or there is dirt on theinlet valve holding it open. A broken spring underthe inlet valve will also keep the valve open.The unloader valve can be cleaned by removingcover (6), spring (8) and unloader valve (9). Cleanthe unloader valve and the passage in the headwhere the unloader valve fits.Install the unloader valve, the spring and thecover. Torque for cover (6) is 60 lb. ft. (8.3 mkg).Start the engine and feel for air coming from theopening where air line (3) was disconnected, if aircan be felt the inlet valve is not closing and thehead assembly must be removed to clean the inletvalve.UNLOADER VALVE6. Cover. 8. Spring. 9. Unloader valve.
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