Turbocharger – Inspect and adjust


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


(1) Turbine housing (2) Compressor housing

Inspect the compressor wheel for damage from a foreign object. If there is damage, determine the source of the foreign object. Replace the turbocharger.
Turn the rotating assembly by hand. While you turn the assembly, 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.
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.
Check the oil level in the crankcase. If the oil level is too high, adjust the oil level.
Inspect the engine crankcase breather. Clean the engine crankcase breather or replace the engine crankcase breather if the engine crankcase breather is plugged.
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.

Inspection of the Turbine Wheel and the Turbine Housing

Remove the air piping from the turbine housing.
Inspect the turbine for damage by a foreign object. If there is damage, determine the source of the foreign object. Replace turbocharger (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.
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 turbocharger (2) if turbine wheel rubs turbine housing (1).
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.
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.
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.
If the oil drain line is damaged, replace the oil drain line.
Check the routing of the oil drain line. Eliminate any sharp restrictive bends. Make sure that the oil drain line is not too close to the engine exhaust manifold.

Inspection of the Wastegate
The wastegate 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 low boost (lug), a spring presses against a diaphragm in the canister. The actuating rod will move and the wastegate actuator will close. The turbocharger can then operate at maximum performance. When the boost pressure increases against the diaphragm in the canister, 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 problem with the wastegate:
• Too high at full load conditions
• Too low at all lug conditions

The boost pressure controls the maximum rpm of the turbocharger, because the boost pressure controls the position of the wastegate. The following factors also affect the maximum rpm of the turbocharger:
• The engine rating
• The horsepower demand on the engine
• The high idle rpm
• Inlet air restriction
• Exhaust system restriction

Check the Wastegate for Proper


Disconnect the pipe for the boost sensor (7) at the wastegate actuator (6). Connect an air supply to the wastegate actuator that can be adjusted accurately.
Install Tooling to the turbocharger so that the end of the actuator rod (4) is in contact with Tooling (A). This will measure axial movement of the actuator rod (4).
Slowly apply air pressure to the wastegate so that the actuator rod (4) moves 1.0 mm (0.039 inch). 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.
If the operation of the wastegate is not correct, the actuator rod (4) can be adjusted. Remove Tooling from the turbocharger.

When the air pressure is applied, loosen the nut (5) on the actuator. Remove the circlip (1). Remove the pin (2) from the actuator rod (4).
When the air pressure is too low, adjust the end of the actuator rod (4) in order to reduce the length of the actuator rod (4). If the air pressure is too high, adjust the end of the actuator rod (4) in order to increase the length of the actuator rod (4).
Install the pin (2) to the actuator rod (4). Install the circlip (1) to the actuator rod (4). Tighten the nut (5) to a torque of 5 N·m (44 lb in).
If the air pressure is correct, remove the air supply. Remove Tooling. Install the pipe for the boost sensor (7)