Page 193 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

Causes of failure of the cooling system and its components

Objectives: At the end of this lesson you shall be able to
• demonstrate Causes of failure of the cooling system and its components.

The failure of a cooling system and its components can be caused by various factors such as
• leaks in hoses: wear and tear, extreme temperature and high pressure poor connection or lines
• leaks in radiator: corrosion, physical damage like impact from road debris or accident can puncture the
radiator, old radiator(age), due to blockage, due to high pressure, improper maintenance.
• leak in water jacket: corrosion, engine overheating, poor maintenance, physical damage, manufacturing
defect.
• A malfunctioning thermostat: stuck closed, stuck open, mechanical failure, incorrect installation, electrical
issue.

• water pump failed: bearing failure due to continuous rotation, seal failure, impeller damage due to corrosion
cavitation or debris ingestion, overheating, contamination of dirt debris or rust particles.
• blockage in system: sediment buildup, corrosion, contaminate of dirt debris or sealant, air pocket creates,
thermostat failure, improper coolant mixture.
• Insufficient coolant level: damaged radiator, hoses, water pump, or cracked engine block.
• issue with the radiator fan: faulty fan motor, a malfunctioning fan relay, a blown fuse or damage wiring.
• issue with the fan belt: wear and tear in over time, leading to cracks, fraying or stretching, improper tension.

• issue with the fan clutch: wear and tear in over time, stuck in engaged or disengaged position.
• faulty thermostat: corrosion, a buildup of debris, electrical or mechanical failure, stuck in open/closed position.
• damage heat gasket: overheating, coolant contamination, engine stress (rapid temperature changes or
extreme pressure), poor installation, age and wear.
• faulty radiator cap: wear and tear, corrosion, damaged cap, improper installation, excessive pressure.
• leak in reserve tank: crack or damaged, loosen or damaged hoses connection, faulty cap seal, overfilling,
coolant degradation.

Importance of testing of pressure cap

Objectives: At the end of this lesson you shall be able to
• demonstrate Importance of testing of pressure cap.

Pressure cap
In normal atmospheric conditions, water boils at 100°C. At the highest altitude, atmospheric pressure is less
and water boils at temperatures below 100°C. To increase the boiling point of water, the pressure of the cooling
system has to be increased. This is achieved by sealing the system with a pressure cap. Cooling losses due to
evaporation can also be reduced by using a pressure cap. This allows the engine to run at higher temperatures
resulting in higher engine efficiency. The pressure cap fits onto the filler neck portion above the radiator tank. If
the pressure increases by 15 PSI, the boiling point temperature increases by 113°C. There are two valves in the
pressure cap

1 Pressure valves
2 VACCUME valve

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CITS : Automotive - Mechanic Diesel - Lesson 47 - 56