C7.1 Industrial Engine Caterpillar

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Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.

Before you begin inspection of the turbocharger, be sure that the inlet air restriction is within the specifications for your engine. Be sure that the exhaust system restriction is within the specifications for your engine. Refer to Systems Operation, Testing, and Adjusting, "Air Inlet and Exhaust System - Inspect".

The condition of the turbocharger will have definite effects on engine performance. Use the following inspections and procedures to determine the condition of the turbocharger.

• Inspection of the compressor and the compressor housing

• Inspection of the turbine wheel and the turbine housing

• Inspection of the wastegate

Inspection of the Compressor and the Compressor Housing

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Illustration 1	g03051436
Typical example (1) Turbine housing (2) Compressor housing (3) Ducts

1. Inspect the compressor wheel and the ducts for damage from a foreign object. The ducts can be removed. If there is damage, determine the source of the foreign object. Replace the turbocharger. If there is no damage, go to step 2.

2. Turn the rotating assembly by hand. While you turn the assembly, use a small force to push the assembly sideways. The assembly should turn freely. The compressor wheel should not rub the compressor housing. The turbocharger must be replaced if the compressor wheel rubs the compressor wheel housing. If there is no rubbing or scraping, go to step 3.

3. Inspect the compressor and the compressor wheel housing for oil leakage. An oil leak from the compressor may deposit oil in the aftercooler. If oil is found in the aftercooler, then drain and clean the aftercooler.

   1. Check the oil level in the crankcase. If the oil level is too high, adjust the oil level.

   2. Inspect the engine air cleaner element. Replace a dirty engine air cleaner element with a clean engine air cleaner element. Refer to Operation and Maintenance Manual, "Engine Air Cleaner Element (Dual Element) - Clean/Replace" or Operation and Maintenance Manual, "Engine Air Cleaner Element (Single Element) - Replace" for the correct procedure. Inspect the engine air cleaner service indicator. Refer to Operation and Maintenance Manual, "Engine Air Cleaner Service Indicator - Inspect" for the correct procedure.

   3. Inspect the engine crankcase breather. Clean the engine crankcase breather or replace the engine crankcase breather if the engine crankcase breather is plugged.

   4. Remove the pipe for the oil drain. Inspect the drain opening. Inspect the oil drain line. Inspect the area between the bearings of the rotating assembly shaft. Look for oil sludge. Inspect the oil drain hole for oil sludge. Inspect the oil drain line for oil sludge in the drain line. If necessary, clean the oil drain line. Replace the oil drain line if there is any sign of damage to the oil drain line.

   5. Inspect the back pressure valve for visual damage. Check that the exposed spring and lever mechanism is free from mud and debris. The operation of the back pressure valve can be checked by turning the keyswitch to the RUN position and then to the OFF position. This will drive the back pressure valve to the CLOSED position for approximately one second and return the back pressure valve to the OPEN position. This motion is visible from the exposed spring and lever mechanism.

   6. If steps 3.a through 3.e did not reveal the source of the oil leakage, the turbocharger has internal damage. Replace the turbocharger.

Inspection of the Turbine Wheel and the Turbine Housing

Remove the air piping from the turbine housing.

1. Inspect the turbine for damage by a foreign object. If there is damage, determine the source of the foreign object. Replace the turbocharger. If there is no damage, go to step 2.

2. Inspect the turbine wheel for the carbon and other foreign material. Inspect turbine housing (1) for carbon and foreign material. Replace the turbocharger, if necessary. If there is no buildup of carbon or foreign material, go to step 3.

3. Turn the rotating assembly by hand. While you turn the assembly, push the assembly sideways. The assembly should turn freely. The turbine wheel should not rub turbine wheel housing (1). Replace the turbocharger if turbine wheel rubs turbine housing (1). If there is no rubbing or scraping, go to step 4.

4. Inspect the turbine and turbine housing (1) for oil leakage. Inspect the turbine and turbine housing (1) for oil coking. Some oil coking may be cleaned. Heavy oil coking may require replacement of the turbocharger. If the oil is coming from the turbocharger center housing go to step 4.a. Otherwise go to "Inspection of the Wastegate".

   1. Remove the pipe for the oil drain. Inspect the drain opening. Inspect the area between the bearings of the rotating assembly shaft. Look for oil sludge. Inspect the oil drain hole for oil sludge. Inspect the oil drain line for oil sludge. If necessary, clean the drain line.

   2. If crankcase pressure is high, or if the oil drain is restricted, pressure in the center housing may be greater than the pressure of turbine housing (1). Oil flow may be forced in the wrong direction and the oil may not drain. Check the crankcase pressure and correct any problems.

   3. If the oil drain line is damaged, replace the oil drain line.

   4. Check the routing of the oil drain line. Eliminate any sharp restrictive bends.

   5. If steps 4.a through 4.d did not reveal the source of the oil leakage, turbocharger has internal damage. Replace the turbocharger.

Inspection of the Wastegate

The wastegate actuator controls the amount of exhaust gas that is allowed to bypass the turbine side of the turbocharger. This valve then controls the rpm of the turbocharger.

When the engine operates in conditions of a low boost (lug), a spring presses against a diaphragm in the canister. The load on the spring holds the wastegate closed. The turbocharger can then operate at maximum performance.

When a boost pressure signal acts against the diaphragm in the wastegate actuator, the pressure overcomes the spring and the wastegate will open. The rpm of the turbocharger becomes limited. The rpm limitation occurs because a portion of the exhaust gases bypass the turbine wheel of the turbocharger.

The following levels of boost pressure indicate a potential problem with the wastegate actuator or wastegate regulator:

• Too high at full load conditions

• Too low at all lug conditions

The boost pressure controls the maximum rpm of the turbocharger, which controls the position of the wastegate. The following factors also affect the maximum rpm of the turbocharger:

• The engine rating

• The power demand on the engine

• The high idle rpm

• Inlet air restriction

• Exhaust system restriction

Note: Check the operation of the wastegate regulator. Refer to Troubleshooting, "Solenoid Valve - Test".

Check the Wastegate for Proper Operation

Illustration 2	g03051438
Typical example

Note: The wastegate actuator is installed to the high-pressure turbocharger.

1. Disconnect the pipe for the boost sensor (1) at the wastegate actuator (2). Connect an air supply to the wastegate actuator that can be adjusted accurately.

2. Install Tooling (A) to the turbocharger so that the end of the actuator rod (3) is in contact with Tooling (A). This will measure axial movement of the actuator rod (3).

3. Slowly apply air pressure to the wastegate so that the actuator rod (3) moves 1.0 mm (0.039 inch). Refer to Specifications, "Turbocharger" for the correct pressure for the wastegate. Ensure that the dial indicator returns to zero when the air pressure is released. Repeat the test several times. This will ensure that an accurate reading is obtained.

4. If the operation of the wastegate is not correct, the turbocharger will need to be replaced.

5. Repeat steps 2 to 3 in order to repeat the pressure test.

6. If the air pressure is correct, remove the air supply. Remove Tooling (A). Install the pipe for the boost sensor (1).