Page 88 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

7 Check the gear teeth of the crank gear and cam shaft, if excessively worn then the gear should be replaced.
8 After tightening the dog nut on the frank shaft pulley, it should be locked with the lock leaf.
9 If the gasket of the tap side cover or timing cover is damaged, it should be replaced.
10 If the chain adjust mouth is excessively worn, it should be replaced.
11 After tightening both the mounting bolts of the chain adjuster, both the bolts should be locked with the lock leaf.
12 After completing work on the job, all tools should be cleaned and kept in their proper place.
Importance of correct valve clearance Precautions to be

observed while assembling engine components

Objectives: At the end of this lesson you shall be able to
• explain Importance of correct valve clearance
• demonstrate Precautions to be observed while assembling engine components.

Importance of correct valve clearance
Valve clearance refers to the space or gap between the camshaft and the top of the valve when the valve is fully
closed. It’s an essential measurement in the engine that ensures proper functioning of the valves. Having the
correct valve clearance is crucial for the valves to open and close at the right time, allowing the engine to operate
smoothly and efficiently. Adjusting the valve clearance is a standard maintenance procedure to keep the engine
running properly.
Proper Engine Performance: Correct valve clearance ensures that the valves open and close at the right
time, allowing the engine to operate efficiently. Incorrect valve clearance can lead to poor engine performance,
including misfires, rough idling, and decreased power.
Prevents Engine Damage: If the valve clearance is too small, the valves may not fully close, leading to overheating
and potential damage to the valves, valve seats, and cylinder head. On the other hand, if the clearance is too
large, the valves may not open fully, reducing engine power and efficiency.

Noise Reduction: Correct valve clearance helps reduce valve train noise, which can be annoying and indicate
potential issues with the engine if excessively loud.
Longevity of Engine Components: Proper valve clearance reduces wear and tear on the valves, rocker arms,
and camshaft, leading to longer engine life.
Fuel Efficiency: Correct valve clearance ensures that the engine operates at its optimum efficiency, leading to
better fuel economy.

Overall, correct valve clearance is essential for ensuring the smooth operation, performance, and longevity of an
engine.
Precautions to be observed while assembling engine components
Assembly of Diesel Engine

The process of assembling and dismantling a diesel engine involves several important steps to ensure its
functionality and safety. During assembly, various engine parts are fitted together based on their mechanical
compatibility, such as the crankshaft and camshaft being installed into the engine block, and the tappet valve and
timing gear being fitted onto the camshaft. Tools capable of opening and closing the engine assembly are used
to facilitate this process.
On the other hand, dismantling a diesel engine from a vehicle is a crucial skill for trainees in the ‘Mechanic Diesel’
trade. This process involves parking the vehicle on a hoist, opening the bonnet, and disconnecting the brake
linkage from the engine. Subsequently, the radiator fan belt is removed, and all pipes or hoses related to the fuel
system are isolated by closing valves. Belts of the fuel pump and other pumps are then disconnected. With the
assistance of a torque wrench, all engine bolts are loosened, and the engine is carefully lifted out of the vehicle
using an engine hoist. It’s essential to remove the engine from the vehicle without causing damage and ensuring
safety throughout the process.

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CITS : Automotive - Mechanic Diesel - Lesson 19 - 24 CITS : Automotive - Mechanic Diesel - Lesson 19 - 24