3Z5-77192-0 Tohatsu MOTOR BRACKET ASSEMBLY

Illustration 1 g01180656
Turbocharger in series
(1) Exhaust valve
(2) Inlet valve
(3) Air-To-Air Aftercooler
(4) Precooler
(5) High pressure turbocharger
(6) Turbine inlet
(7) Wastegate
(8) Compressor outlet
(9) Turbine outlet
(10) Compressor inlet
(11) Turbine inlet
(12) Hose for the wastegate
(13) Turbine outlet
(14) Compressor outlet
(15) Low pressure turbocharger
(16) Compressor inlet Basic Operation
The following components make up the air inlet and exhaust system:
Low pressure turbocharger
High pressure turbocharger
Precooler
Aftercooler
Cylinder head
Valves and valve train components
Piston and cylinder
Exhaust manifoldThe engines are equipped with two turbochargers in series. Turbocharged engines are more responsive and turbocharged engines have increased horsepower. Air is drawn through the air cleaner and flows to the compressor side of the low pressure turbocharger. The low pressure turbocharger compresses the air in order to create boost. The compressed air is sent to the air inlet of the high pressure turbocharger. The high pressure turbocharger compresses the air in order to create higher boost pressures. After the air exits from the high pressure turbocharger the compressed air is cooled by the precooler.The precooler is a heat exchanger. The precooler uses coolant to extract the heat from the compressed air. The air then flows through the Air-to-Air Aftercooler (ATAAC). The air will then enter the cylinder head. The water supply for the precooler is regulated. The water supply is shut off below 1200 RPM. Cooling the compressed air increases combustion efficiency. The inlet valves control the air flow into the combustion chamber. Each cylinder contains two inlet valves and two exhaust valves. The inlet valves open when the piston moves down on the inlet stroke. When the inlet valves open, cooled compressed air is pulled into the cylinder. The inlet valves close and the piston begins to move up on the compression stroke. The air in the cylinder is compressed. When the piston is near the top of the compression stroke, fuel is injected into the cylinder. The fuel mixes with the air and combustion occurs. During the power stroke, the combustion force pushes the piston downward. The exhaust valves open and the exhaust gases are pushed through the exhaust port into the exhaust manifold as the piston rises on the exhaust stroke. After the exhaust stroke, the exhaust valves close and the cycle starts again. The complete cycle consists of four strokes:
Intake
Compression
Power
ExhaustTurbocharger
Illustration 2 g01114531
(1) Compressor housing
(2) Oil inlet port
(3) Bearing
(4) Turbine housing
(5) Turbine wheel
(6) Air inlet
(7) Exhaust outlet
(8) Compressor wheel
(9) Bearing
(10) Oil outlet port
(11) Exhaust inlet The two turbochargers work together in order to produce boost across the entire engine RPM range. The increased boost at low RPM fills the combustion chamber with dense air. The dense air mixes with the fuel in order to promote a complete combustion.The turbochargers have a compressor wheel (8) and a turbine wheel (5). The compressor wheel and the turbine wheel are connected to a common shaft. The shaft is supported by bearings (3 & 9). The bearings are lubricated by pressurized engine oil. The oil enters through oil inlet port (2). The engine oil lubricates the bearings and the oil removes heat. The oil returns to the oil pan through oil outlet port (10).The high pressure turbocharger is equipped with a wastegate which is actuated by the boost from the low pressure turbocharger. The wastegate controls boost pressure. The wastegate is controlled by the pressure against the diaphragm in the canister for the wastegate. The canister consists of a spring and a diaphragm. The boost pressure creates a force against the diaphragm. The pressure against the diaphragm causes the diaphragm to move. The actuating lever is connected to the diaphragm. The movement of the actuating lever controls the position of the wastegate. The movement of the wastegate allows exhaust gases to bypass the turbine wheel. When the exhaust bypasses the turbine wheel the rotation of the compressor wheel slows down. Boost level is determined by the RPM of the compressor wheel.Valve System Components
Illustration 3 g01114533
(1) Rocker arm
(2) Pushrod
(3) Valve bridge
(4) Valve spring
(5) Valve
(6) Lifter The valve system components control the flow of inlet air into the cylinders and out of the cylinders during engine operation. The valve mechanism also operates the fuel injector.The camshaft must be timed to the crankshaft in order to get the correct relation between the piston movement and the valve movement.The camshaft has two camshaft lobes for each cylinder. The lobes operate the inlet and exhaust valves. As the camshaft turns, lobes on the camshaft cause lifters (6) to move pushrods (2) up and down. Upward movement of the pushrods against rocker arms (1) results in downward movement (opening) of valves (5).Each cylinder has two inlet valves and two exhaust valves. The valves are actuated at the same time by a valve bridge (3). Valve springs (4) close the valves when the lifters move down.Variable Valve Actuator
Illustration 4 g01114534
Do not disassemble the Variable Valve Actuator. There are no components of the Variable Valve Actuator that are serviceable. If the Variable Valve Actuator is disassembled, the warranty will be void.
The variable valve actuator and the Cat compression brake use engine oil for operation. Variable Valve Actuator
Illustration 5 g00948824The variable valve actuator is used to control the closing of the inlet valves. The variable valve actuator does not operate until the engine has reached a desired temperature. The oil for the variable valve actuator flows from the oil filter base to the valve cover base. The oil bypass valve is located in the valve cover base. The bypass valve is open when the engine is below normal operating temperatures. The oil drains into the valve cover. The ECM is programmed to close the oil bypass valve at a preset temperature. When the valve closes the oil will flow into the housing of the variable valve actuator. The oil will fill the passageways for operation. The variable valve actuator exhausts a small quantity of oil at the base of the solenoids. The majority of the oil in the variable valve actuator is evacuated back into the oil supply rail.The variable valve actuator holds the inlet valves open. The valves would normally close with the profile of the camshaft lobe. The