Air Inlet and Exhaust System 66 UENR0623-02 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. 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. 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.
When a boost pressure signal acts against the diaphragm in the wastegate, the pressure overcomes the spring and the wastegate actuator 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. 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 the turbine wheel rubs turbine housing (1). If there is no rubbing or scraping, go to step 4.
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 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”. 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 power demand on the engine a. Remove the pipe for the oil drain. Inspect the drain opening. Inspect the area between the bearings of the rotating assembly shaft. Look for the oil sludge. Inspect the oil drain hole for the oil sludge. Inspect the oil drain line for the oil sludge. If necessary, clean the drain line. The high idle rpm Inlet air restriction Exhaust system restriction Note: Check the operation of the wastegate regulator. Refer to Troubleshooting, “Solenoid Valve - Test”. b.
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. Check the Wastegate for Proper Operation Table 6 c. If the oil drain line is damaged, replace the oil drain line. d. 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. e. If steps 4.a through 4.d did not reveal the source of the oil leakage, turbocharger (3) 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. Required Tools Tool Part Number Part Description QTY A 21825617 Dial Gauge 1