Komatsu 4D88E, 4D98E, 4D106 Series Engine Manual

Table of Contents

1. General …………………………………………………………………………………………. 1
2. Inspection and Adjustment……………………………………………………………… 22
3. TROUBLESHOOTING…………………………………………………………………… 53
4. Disassembly, Inspection and Reassembly of Engines………………………… 59
5. LUBRICATION SYSTEM ……………………………………………………………… 108
6. COOLING SYSTEM………………………………………………………………………112
7. FUEL INJECTION PUMP/GOVERNOR……………………………………………114
8. TURBOCHAGER: Disassembly, inspection and reassembly…………………118
9. STARTING MOTOR…………………………………………………………………….. 140
10. ALTERNATOR…………………………………………………………………………… 176
11. ELECTRIC WIRING …………………………………………………………………… 180
12. SERVICE STANDARDS …………………………………………………………….. 185
13. TIGHTENING TORQUE for BOLTS and NUTS ……………………………… 196

Breather system (A reductor to intake air system of blowby gas)

Emitting blowby gas is harmful to the natural environment. Therefore, a blowby gas reductor is adopted to TNV series naturally aspirated engines as a breather system (Turbocharged engines emit blowby gas).

The system of model 3/4TNV84 is shown as a representative of that breather system in the right figure. Some of the combustion gas passes through the clearance between the cylinder and the piston, piston ring, and flows to the crankcase. This is said to be blowby gas. While it passes into the cylinder head and the rocker arm cover, the blowby gas mixes with splash oil and becomes oil mist. The blowby gas, with passing through the baffle plate inside a rocker arm cover, passes through a diaphragm assembly, and an intake manifold, and is reduced in the combustion chamber. Pressure inside a crankcase is controlled by the function of the diaphragm assembly, and a suitable amount of blowby gas is reduced in the intake air system.