MBE 4000 DDEC VI Troubleshooting – Section 8.2 Defective Air Compressor

Section 8.2
Defective Air Compressor

To determine if a defective air compressor is causing excessive crankcase pressure, perform the following:‪

1. Perform a crankcase pressure test and record the test results; refer to "2.1 Crankcase Pressure Test" .
2. Disconnect the air discharge line from the air compressor; see Figure "Air Line Attachments" for air line attachments. Refer to the MBE 4000 Service Manual (6SE420 , Chapter 11, “Special Equipment”.
   

   1. Discharge Port‪	4. Unloader Port‪
   2. Unloader Air Line‪	5. Discharge Air Line‪
   3. Intake Air Line‪	6. Air Compressor‪

   Figure 1. Air Line Attachments

3. Repeat step 1 and record test results.
4. Compare the results of test one with test two.
   1. If the engine crankcase pressure remained the same, check the turbocharger;
   2. If the engine crankcase pressure decreased, repair or replace the air compressor; refer to "8.2.1 Test Engine with Repaired Air Compressor" , test engine with repaired air compressor

Section 8.2.1
Test Engine with Repaired Air Compressor

Perform the following steps to determine if a repaired air compressor resolved the excessive crankcase pressure:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.‪

1. Start and run the engine.
2. Perform a crankcase pressure test; refer to "2.1 Crankcase Pressure Test" .
   1. If the engine crankcase pressure is within 0.62 kPa (2.5 in. H₂ O), no further troubleshooting is required. Shut down the engine.
   2. If the engine crankcase pressure is not within 0.62 kPa (2.5 in. H₂ O), shutdown the engine. Check the turbocharger; refer to "8.3 Defective Turbocharger"