Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.
Personal injury can result from rotating and moving parts.
Stay clear of all rotating and moving parts.
Never attempt adjustments while the machine is moving or the engine is running unless otherwise specified.
The machine must be parked on a level surface and the engine stopped.
Keep all parts clean from contaminants.
Contaminants may cause rapid wear and shortened component life.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.
Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.
Dispose of all fluids according to local regulations and mandates.
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 Testing and Adjusting, "Air Inlet and Exhaust System - Inspect".
(1) Turbine wheel housing
(2) Compressor wheel housing
(3) Turbocharger oil lines
(4) Coolant lines for the turbocharger
(5) Wastegate for the turbocharger
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.
- Inspect the turbine wheel and turbine wheel housing (1).
- Inspect the compressor wheel and compressor wheel housing (2).
- Inspect the oil lines for plugging (3).
- Inspect condition of the coolant lines (4).
- Inspect wastegate (5) for the turbocharger.
Remove the air piping from the turbine housing.
- Inspect the turbine wheel for damage by foreign material. If there is damage, determine the source of the damage. Replace the turbocharger. If there is no damage, go to Step 3.
- Inspect the turbine wheel for buildup of carbon and other foreign material. Inspect the turbine wheel housing for buildup of carbon and foreign material. Clean the turbine wheel and clean the turbine housing if you find buildup of carbon or foreign material. If there is no buildup of carbon or foreign material, go to Step 3.
- Turn the rotating assembly by hand. While you turn the assembly, push the assembly to the limits of the side-to-side end play. The assembly should turn freely. The turbine wheel should not rub the turbine wheel housing. Replace the turbocharger if the turbine wheel rubs the turbine housing. If there is no rubbing or scraping, go to Step 4.
- Inspect the turbine wheel and the turbine wheel housing for oil leakage. Inspect the turbine wheel and the turbine wheel housing for oil coking. Some oil coking may be cleaned. Heavy oil coking may require replacement of the turbocharger. If the oil is found in the turbine wheel housing, go to "Inspection of the Oil Lines".
Remove air piping from the compressor inlet.
- Inspect the compressor wheel for damage from foreign objects. If there is damage, determine the source of the damage. As required, clean the inlet system and repair the components of the intake system. Replace the turbocharger. If no damage is found, go to Step 3.
- Clean the compressor wheel and the compressor wheel housing. If you find buildup of foreign material determine the source of the material. As required, clean the inlet system and repair the components of the intake system. If there is no buildup of foreign material, go to Step 3.
- Turn the rotating assembly by hand. While you turn the assembly, push the assembly to the limits of the side-to-side end play. The assembly should turn freely. The compressor wheel should not rub the compressor wheel housing. Replace the turbocharger if the compressor wheel rubs the compressor wheel housing. If there is no rubbing or scraping, go to Step 4.
- Inspect the compressor and the compressor wheel housing for oil leakage. An oil leak from the compressor may deposit oil in the aftercooler. The aftercooler must then be cleaned. If oil is found in the compressor wheel housing, go to "Inspection of the Oil Lines".
(6) Oil supply line
(7) Oil drain line
- Ensure that the turbocharger is receiving an adequate oil supply from the engine's lubrication system.
- Remove oil supply line (6) and oil drain line (7) from the turbocharger.
- Inspect the supply port and the drain port of the turbocharger. Inspect the area between the bearings of the rotating assembly shaft. Look for oil sludge.
- Inspect the oil drain hole for oil sludge.
- If necessary, clean the rotating assembly shaft.
- If necessary, clean the supply port and the drain port.
- 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 wheel housing. Oil flow may be forced in the wrong direction and the oil may not drain. Check the crankcase pressure and correct any problems.
- Inspect the air cleaner element for restriction. If restriction is found, clean the element or replace the element.
- Inspect the engine crankcase breather for plugging. If necessary, clean the engine crankcase breather or replace the engine crankcase breather.
- If the oil drain line is damaged, replace the oil drain line.
- Check the routing of the oil lines. Eliminate any sharp restrictive bends. Make sure that the oil lines are not too close to the engine exhaust manifold.
If the source of the oil leakage is not apparent, the turbocharger may have internal damage. Replace the turbocharger.
(8) Coolant supply line
(9) Coolant drain line
Ensure that the turbocharger is receiving an adequate coolant flow from the engine's cooling system. Check for plugging in the coolant supply and the coolant return lines.
- Remove coolant supply line (8) and coolant return line (9) from the turbocharger. Inspect the lines for a buildup of debris or for contamination. If debris is found in the lines, determine the source of the contamination. If necessary, repair the cooling system.
- Inspect the turbocharger's cooling passages. Inspect the passages for buildup of debris or for contamination. If debris is found in the turbocharger's cooling passages, determine the source of the contamination. If necessary, repair the cooling system.
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 will close. Then, the turbocharger can 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. This limitation occurs because a portion of the exhaust gases are directed around the turbine wheel of the turbocharger.
The following levels of boost pressure indicate a problem with the wastegate:
- Boost pressure is too high at full load conditions.
- Boost pressure is too low at all lug conditions.
Note: The housing assembly for the wastegate is preset at the factory and no adjustments can be made.
If the high idle rpm or the engine rating is higher than given in the Technical Marketing Information (TMI) for the height above sea level at which the engine is operated, there can be damage to engine or to turbocharger parts. Damage will result when increased heat and/or friction due to the higher engine output goes beyond the engine cooling and lubrication system's abilities.
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:
- Engine rating
- Horsepower demand on the engine
- High idle rpm
- Operating altitude of the engine
- Inlet air restriction
- Exhaust system restriction