910121-0616 Tohatsu BOLT

Illustration 1 g00327243
Air inlet and exhaust system
(1) Exhaust manifold. (2) Inlet manifold and aftercooler. (3) Engine cylinder. (4) Air inlet. (5) Turbocharger compressor wheel. (6) Turbocharger turbine wheel. (7) Exhaust outlet.
Clean inlet air from the air cleaner is pulled through air inlet (4) of the turbocharger by the turning of compressor wheel (5). The compressor wheel causes a compression of the air. The air then flows to the aftercooler (if equipped), and then to inlet manifold (2) of the engine. When the intake valves open, the air flows into engine cylinders (3). The air is mixed with the fuel for combustion. When the exhaust valves open, the exhaust gases go out of the engine cylinders and into exhaust manifold (1). From the exhaust manifold, the exhaust gases flow through the blades of turbine wheel (6). This causes the turbine wheel and compressor wheel to turn. The exhaust gases then flow out of exhaust outlet (7) of the turbocharger.
Illustration 2 g00332861
Air inlet and exhaust system 3412C shown
(1) Exhaust manifold. (2) Inlet manifold and aftercooler. (4) Air inlet. (7) Exhaust outlet. (8) Turbocharger. (9) Cylinder head.
Illustration 3 g00332863
Air flow schematic 3408C
(1) Exhaust manifold. (2) Inlet manifold and aftercooler. (4) Air inlet. (7) Exhaust outlet. (8) Turbocharger.
Illustration 4 g00332864
Air flow schematic 3412C
(1) Exhaust manifold. (2) Inlet manifold and aftercooler. (4) Air inlet. (7) Exhaust outlet. (8) Turbochargers.
Aftercooler
Some engines have an aftercooler (3). The aftercooler is installed above the inlet manifold.
Illustration 5 g00332924
Air inlet system 3412C
(1) Turbocharger. (2) Aftercooler. (3) Compressed air from the turbocharger. (4) Elbow on the front bonnet of the oil cooler.
The aftercooler has a core assembly that is charged by coolant. Coolant from elbow (4) on the front bonnet of the oil cooler flows through the aftercooler core assembly. The coolant then flows out of the aftercooler through a different pipe into the rear of the cylinder block.The inlet air from the compressor side of the turbocharger flows into the aftercooler. The air passes through the core assembly which lowers the temperature as much as 38°C to 93°C (100°F to 200°F). The cooler air flows out of the bottom of the aftercooler and into the air chamber. The cooler air then flows through the inlet ports (passages) in the cylinder heads.Turbocharger
Illustration 6 g00332927
Turbocharger 3408C and 3412C
(1) Exhaust manifolds. (2) Oil drain line. (3) Oil supply line. (4) Air inlet. (7) Exhaust outlet. (20) Air outlet. (21) Turbocharger.
A single turbocharger is installed at the rear of the engine on a cross pipe between the two exhaust manifolds on 3408C and some 3412C engines. All the exhaust gases from the engine go through the turbocharger.On some of the 3412C engines, two turbochargers are mounted on the rear of the engine. All of the exhaust gases from the left exhaust manifold goes through the left turbocharger, and the right turbocharger uses the exhaust from the right exhaust manifold.
Illustration 7 g00332934
Turbochargers 3412C
(1) Exhaust manifolds. (2) Oil drain lines. (3) Oil supply line (one on each side). (4) Air inlet. (7) Exhaust outlet. (20) Air outlet. (21) Turbochargers.
Illustration 8 g00332960
Turbocharger (typical example)
(4) Air inlet. (5) Compressor wheel. (6) Turbine wheel. (7) Exhaust outlet. (8) Compressor housing. (9) Thrust bearing. (10) Sleeve. (11) Lubrication inlet port. (12) Turbine housing. (13) Sleeve. (14) Sleeve. (15) Oil deflector. (16) Bearing. (17) Oil outlet port. (18) Bearing. (19) Exhaust inlet. (20) Air outlet.
The exhaust gases go into the turbine housing (12) and the exhaust gases push the blades of the turbine wheel (6). This causes the turbine wheel and the compressor wheel to turn at a rate up to 70,000 rpm.Clean air from the air cleaners is pulled through the compressor housing air inlet (4) by the rotation of the compressor wheel (5). The action of the compressor wheel blades causes a compression of the inlet air. This compression gives the engine more power. The engine gets more power because the engine is able to burn more air and more fuel during combustion.The maximum rpm of the turbocharger is controlled by the following items:
the fuel setting
the high idle rpm setting
the height above sea level
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 bearings (16) and (18) in the turbocharger u