C7 and C9 On-Highway Engines Caterpillar

The oil may be present on the outside of the air line or on the inside of the air line. The presence of oil does not indicate that the turbocharger must be replaced. In most cases, the turbocharger is okay. Usually, another problem is causing oil to leak from the turbocharger. The root cause must be identified and repaired in order to stop the oil from leaking from the turbocharger.

Probable Causes

• There is excessive crankcase pressure (caused by a plugged crankcase breather or a plugged crankcase fumes fitting).

• The engine oil contains fuel.

• There is a leak in the air lines between the turbocharger and the engine inlet.

• The engine has high back pressure.

• There is high flow of Clean Gas Induction (CGI).

• There is a problem with the turbocharger.

Troubleshooting Procedure

The following list provides a way to classify the oil leak. The amount of oil determines the troubleshooting that must be performed.

Heavy Oil Leak - There is oil on the outside of an air line. The oil is leaking from an air line connection.

Moderate Oil Leak - Oil is not leaking from an air line connection. Oil has collected on the inside of an air line. The oil drips from the air line when the air line is disconnected.

Minor Oil Leak - Oil is not leaking from an air line connection. Oil has collected on the inside of an air line. The oil does not drip from the air line when the air line is disconnected.

Slight Oil Leak - Oil is not leaking from an air line connection. However, there are streaks of oil on the inside of an air line. A slight oil leak from the turbocharger is normal. No troubleshooting is required if there is a slight oil leak.

1. No troubleshooting is required if there is a slight oil leak. Wipe the inside of the air line if there is a slight oil leak.

2. Inspect the following components if the oil leak is heavy, moderate, or minor.

   Turbocharger Compressor Housing - Inspect the housing for signs of wear and of rubbing. If the turbocharger compressor housing has signs of wear or of rubbing, replace the turbocharger. Continue with this procedure after the turbocharger has been replaced.

   Turbocharger Compressor Wheel - Inspect the outside edges of the compressor wheel for signs of wear and of rubbing. If the compressor wheel has signs of wear or of rubbing, replace the turbocharger. Continue with this procedure after the turbocharger has been replaced.

3. Check for the logged diagnostic codes that are listed in Table 1.
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   Table 1

   Diagnostic Trouble Codes That Relate to Oil in an Air Line
   Suspect Parameter Number (SPN)	Failure Mode Identifier (FMI)	Description
   102	18	Engine Intake Manifold #1 Pressure : Low - Moderate Severity (2)
   3251	0	Diesel Particulate Filter Differential Pressure (bank 1) : High - Most Severe (3)
   3251	16	Diesel Particulate Filter Differential Pressure (bank 1) : High - Moderate Severity (2)
   520192	16	CGI Mass Flow Rate : High - Moderate Severity (2)
   101	15	Engine Crankcase Pressure : High - Least Severe (1)
   101	16	Engine Crankcase Pressure : High - Moderate Severity (2)
   101	18	Engine Crankcase Pressure : Low - Moderate Severity (2)

   If any of the codes in Table 1 are logged, refer to the appropriate troubleshooting procedure. Clean the oil from the air lines. Troubleshooting for this problem is complete.

   If none of the codes in Table 1 are logged, continue to Test Step 4.

4. Perform the Air System Verification Test. Refer to Troubleshooting, "Air System Verification Test" for the following information:
   • Description of the test

   • Acceptable values for the test results

   • Troubleshooting procedures for unacceptable test results

   If the test results are unacceptable, refer to the appropriate troubleshooting procedure. Make the necessary repairs. Clean the oil from the air lines. Troubleshooting for this problem is complete.

   If the test results are acceptable, continue to Test Step 5.

5. Check for the presence of fuel in the engine oil.

   If the oil contains fuel, refer to Troubleshooting, "Oil Contains Fuel". Clean the oil from the air lines. Troubleshooting for this problem is complete.

   If the oil does not contain fuel, continue to Test Step 6.

6. Inspect the air lines and the components between the outlet of the turbocharger compressor and the engine air intake. Look for the following problems:
   • Loose clamps

   • Cracks, holes, or tears in the flexible connectors

   • Cracked lines and broken lines

   • Cracked components or leaky components

   If a problem is found, make the necessary repairs. Clean the oil from the air lines. Troubleshooting for this problem is complete.

   If the air lines and the components are okay, proceed to Test Step 7.

Note: The engine must be assembled in order to perform the following tests. Ensure that all air lines for the system are connected.

7. Start the engine. Allow the engine to idle. Check the air lines and the components between the outlet of the turbocharger compressor and the engine air intake for air leaks. Use the Caterpillar Electronic Technician (ET) to monitor the crankcase pressure while the engine is idling. The "Engine Crankcase Differential Pressure" status parameter indicates the crankcase pressure. This parameter is not in any of the default status groups. The parameter must be added to a new group of parameters in order to view the crankcase pressure.

   If the crankcase pressure is greater than 14 kPa (2 psi), refer to Troubleshooting, "Crankcase Pressure Is High". Clean the oil from the air lines. Troubleshooting for this problem is complete.

   If the crankcase pressure is below 14 kPa (2 psi) at idle, proceed to Test Step 8.

   Note: In rare instances the crankcase fumes fitting can be plugged and the crankcase pressure will not exceed 14 kPa (2 psi) at idle. Refer to the Operation and Maintenance Manual, "Crankcase Fumes Fitting - Inspect/Clean" to check this fitting.

8. Use Cat ET to measure the differential pressure across the Diesel Particulate Filter (DPF) while the engine is operating at 1400 rpm for 30 seconds. The "Diesel Particulate Trap #1 Differential Pressure" status parameter indicates the differential pressure across the DPF. This parameter is not in any of the default status groups. The parameter must be added to a new group of parameters in order to view the differential pressure.

   If the differential pressure is greater than 14 kPa (2 psi), refer to Troubleshooting, "Diesel Particulate Filter Has Differential Pressure Problem". Clean the oil from the air lines. Troubleshooting for this problem is complete.