MBE 900 DDEC VI Troubleshooting – Section 7.4 Defective Air Compressor

Section 7.4
Defective Air Compressor

To determine if a defective air compressor is causing excessive oil consumption, 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" ; refer to MBE 900 Service Manual (6SE9007), special equipment chapter.
   

   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 the results.
4. Compare the results of test one with test two.
   1. If the engine crankcase pressure remained the same, check the turbocharger; refer to "7.5 Defective Turbocharger" .
   2. If the engine crankcase pressure decreased, replace the air compressor; refer to MBE 900 Service Manual (6SE9007), special equipment chapter. Verify the replaced (or new) air compressor, refer to "7.4.1 Test Engine with Repaired Air Compressor" .

Section 7.4.1
Test Engine with Repaired Air Compressor

Perform the following steps to determine if the replaced (or new) 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 exceeds 0.62 kPa (2.5 in. H₂ O), shut down the engine. Check for defective turbocharger. refer to "7.5 Defective Turbocharger" .
   2. If the engine crankcase pressure is within 0.62 kPa (2.5 in. H₂ O), shut down the engine; no further troubleshooting is required.