Problem 
 | Action 
 | 
Loose drive gear or pulley 
 | 
 Important: Do not back off the crankshaft nut in order to align the cotter pin and the castellated nut. Some compressors do not use castellated nuts. Do not use impact wrenches.
 
|     •  | The pulley on the gear must be completely seated and the crankshaft nut must be tight. |  
  
|     •  | If the compressor crankshaft surface or the keyway is damaged, the drive components are loose. |  
  
|     •  | If damage to the compressor crankshaft is detected, replace the compressor. |  
  
|     •  |  When installing the drive gear or pulley, torque the crankshaft nut to the appropriate torque specifications. |  
  
 | 
Excessively worn drive couplings or gears 
 | 
- Inspect drive gear and couplings and engine for excessive wear . 
 
- Replace as necessary. 
 
Non-metallic gears should be replaced when the compressor is changed. 
 
 | 
Compressor cylinder head or discharge line restrictions 
 | 
- Inspect the compressor discharge port and discharge line for carbon build-up. 
 
- If carbon is detected, check for proper cooling to the compressor. 
 
- Inspect the discharge line for kinks and restrictions. 
 
- Replace discharge line as necessary.
 
 
 | 
Worn or burned out bearings 
 | Check for proper oil pressure in the compressor.  
Specification
 |     •  | The minimum required oil pressure with the engine idling is 103 kPa (15 psi). |  
  
|     •  | Check for excessive oil temperature. The temperature should not exceed 116°C (240°F). |  
  
 | 
Faulty compressor 
 | Replace or repair the compressor after determining none of the preceding installation defects exist. 
 |