Exhaust Manifold W/ Turbocharger System Description

State of Turbocharger Failure Repair
It is well known that turbocharger malfunctions cause many symptoms, such as those shown below. However, the mechanisms resulting in these symptoms that indicate turbocharger malfunctions are not well understood. As a result, many unnecessary turbocharger replacements and other repairs are performed due to lack of knowledge about the turbocharger and turbocharger failure. Therefore, knowing the facts regarding turbocharger malfunctions is useful for making effective repairs and saving time.

Turbocharger Failure Classification

HINT:

This table shows only typical problems related to the turbocharger.

Connect the GTS to the DLC3.

Start the engine and warm it up.

Turn the GTS on.

Enter the following menus: Powertrain / Engine / Active Test / Activate the VN Turbo Open.

HINT:

1. w/ Urea SCR System:
   For details regarding the troubleshooting of noise, refer to (LandCruiser RM00000416S0AYX.html).
   
2. w/o Urea SCR System:
   For details regarding the troubleshooting of noise, refer to (LandCruiser RM00000416S0AZX.html).
   

Malfunctions are classified into 2 types as shown below.

Main Components Related to Black Smoke

HINT:

1. w/ Urea SCR System:
   The components listed above are only the main components. Not all the components potentially related to black smoke are listed. For details regarding the troubleshooting of black smoke, refer to (LandCruiser RM000000TIR0JGX.html).
   
2. w/o Urea SCR System:
   The components listed above are only the main components. Not all the components potentially related to black smoke are listed. For details regarding the troubleshooting of black smoke, refer to (LandCruiser RM000000TIR0JIX.html).
   

Relation between Turbocharger and Black Smoke
If the boost pressure is below normal due to a turbocharger failure, black smoke may occur due to a lack of mass air flow. However, abnormally low boost pressure can be caused by the failure of various components, such as intake lines, the EGR valve, etc. Therefore, do not assume that the turbocharger is the cause of abnormally low boost pressure, but check all the components possibly related to abnormally low boost pressure. Components related to abnormal boost pressure are shown in a chart listed in the On-vehicle Inspection for Intake System (LandCruiser RM000001A3W03SX.html). For simple and effective troubleshooting, refer to the chart before starting troubleshooting.

Malfunctions are classified into 2 types as shown below.

Main Components Related to Lack of Power and Hesitation

HINT:

1. w/ Urea SCR System:
   The components listed above are only the main components. Not all the components potentially related to lack of power and hesitation are listed. For details regarding the troubleshooting of lack of power and hesitation, refer to (LandCruiser RM000000W0E0F5X.html).
   
2. w/o Urea SCR System:
   The components listed above are only the main components. Not all the components potentially related to lack of power and hesitation are listed. For details regarding the troubleshooting of lack of power and hesitation, refer to (LandCruiser RM000000W0E0F6X.html).
   

Relation between Turbocharger and Abnormal Boost Pressure
If the boost pressure is below normal due to a turbocharger failure, lack of power could occur due to an intake air volume shortage. However, abnormal boost pressure can be caused by the failure of various components, such as intake lines, the EGR valve, etc. Therefore, do not assume that the turbocharger is the cause of abnormal boost pressure, but check all the components possibly related to abnormal boost pressure. Components related to abnormal boost pressure are shown in a chart listed in the On-vehicle Inspection for Intake System (LandCruiser RM000001A3W03SX.html). For simple and effective troubleshooting, refer to the chart before starting troubleshooting.

A turbocharger is a component used to supply a larger air volume to the cylinders by recovering exhaust gas energy using a turbine coaxially connected to a compressor.

Principle of Turbocharging
Boost pressure is proportional to turbocharger speed, because the intake air is accelerated by centrifugal force generated by the rotation of the compressor and the increased kinetic energy, i.e. the velocity of the intake air, is converted to pressure energy by the diffuser located around the outlet of the compressor impeller. The compressor is driven by the turbine connected coaxially to the turbine shaft. The turbine is driven by exhaust gas energy. Therefore, when the turbocharger begins boosting the intake air, a larger air volume is supplied to the cylinders and more fuel can be injected. As a result, more exhaust energy is available and the turbocharger boost increases.

HINT:

1. Above illustration is an example.
   
2. *a: If sufficient exhaust gas energy is not available, the turbocharger cannot generate the required boost pressure even when the turbocharger does not have a malfunction.
   
3. Considering the fact that the turbocharger is driven by exhaust gas energy, if sufficient exhaust gas is not available due to abnormal injection volume, etc., the required boost pressure will not be available even when the turbocharger does not have a malfunction. Therefore, when boost pressure is abnormally low, checking all the related components using the correct troubleshooting procedure is necessary for simple and effective repair.
   

Boost Pressure Control
The amount of energy the turbine can obtain from the exhaust gas is proportional to the expansion ratio, which is defined as the ratio of the turbine inlet exhaust gas pressure to the pressure at the turbine outlet. To control boost pressure, a Variable Nozzle (VN) is used just upstream of the turbine wheel inlet, and controls the expansion ratio. If the VN is closed, the gap between neighboring vanes is narrowed and the turbine inlet exhaust gas pressure, and correspondingly the expansion ratio, increases. Therefore, when the VN is closed, the turbine receives more energy, and the turbine speed and boost pressure increase. If the VN is opened, the turbine inlet exhaust gas pressure decreases and the turbine speed and boost pressure decrease.

HINT:

1. Above illustration is an example.
   
2. If the VN is stuck open, the necessary boost pressure is not available. If the VN is stuck closed, overboost occurs.
   

Mechanical Construction of Turbocharger

Text in Illustration

*1	VN Actuator (DC Motor)	*2	VN Actuating Rod
*3	Bearing Housing	*4	Turbine Shaft
*5	Turbine Side Seal Ring	*6	Turbine Housing
*7	Turbine Wheel	*8	Thrust Bearing
*9	Compressor Side Seal Ring	*10	Compressor Housing
*11	Compressor Impeller	*12	Radial Bearing
*13	Oil Drain	*14	VN (Variable Nozzle)
*a	See HINT below	*b	See HINT below
	Exhaust Gas Flow		Intake Air Flow

HINT:

1. Above illustration is an example.
   
2. *a: A certain amount of oil mist from PCV gas is contained in the intake air. Therefore, a certain amount of oil at the inlet of the compressor is normal, and is not an oil leak.
   
3. b: The seal rings are C-shaped rings just like piston rings, and have a gap. Therefore, complete sealing is impossible by the seal rings alone. The oil is sealed in with the aid of the boost pressure in the compressor housing, and the exhaust gas pressure in the turbine housing. These pressures prevent oil from exiting the bearing housing through the gap of the seal rings. Therefore, if the turbine shaft is inclined from the horizontal, oil may flow out through the gap of a seal ring. This should not be interpreted as an oil leak due to seal ring failure.