TURBOCHARGER GP 4763225 - Caterpillar

Symptom
The air compressor constantly cycles. The air compressor remains unloaded for a very short time.Probable Cause
Leaking unloader piston
Illustration 1 g00815907
Drain the air system. Disconnect the unloader line. Remove the inlet fitting of the air compressor. Pressurize the unloader port (1) of the air compressor with shop air. Check for air leakage while the air compressor is unloaded. No leakage should be detected. Replace the cylinder head if the unloader valve does not operate properly.
Faulty governor or synchronization valve
Illustration 2 g00816006
Table 1
D-2 Governor    
Callout     Description    
1     Exhaust Port    
2     Unloader Port    
3     Reservoir Port    Use only the Bendix D-2 governor with Bendix DuraFlo 596 air compressors. Verify that the governor is of the proper type and that the pressure rating of the governor is 760 kPa (110 psi) to 900 kPa (130 psi). Test the governor for proper operation. Test the governor by charging the supply tank with shop air to a pressure of 900 kPa (130 psi). No air should be exhausting from the exhaust port (1) of the governor. Repair the governor or replace the governor, if necessary.
Illustration 3 g00816008
Table 2
SV-1 Synchronization Valve    
Callout     Description    
1     Exhaust Port    
2     Control Port    
3     Delivery Port    
4     Supply Port    Use only the Bendix SV-1 synchronization valve with Bendix DuraFlo 596 air compressors. Verify that the synchronization valve is of the proper type. Test the synchronization valve for proper operation. Test the synchronization valve by charging the supply tank with shop air to a pressure of 920 kPa (130 psi). No air should be exhausting from the exhaust port of the SV-1. Repair the synchronization valve or replace the synchronization valve, if necessary.
Excessive system leakage
Illustration 4 g00816506
Inspect all fittings and all air lines for leakage. Check the fittings of the air dryer for leakage. Check the air dryer purge valve (1) for leakage. Test the air dryer purge valve by charging the air system to 900 kPa (130 psi). No air should be leaking from the purge valve. The check valve may be malfunctioning if leakage is observed.
Excessive contaminants in the reservoirDrain the reservoirs.