UNIT 7.4

Cooling System

Maintain efficient engine temperature under ALL OPERATING CONDITIONS and provides quick warm up of the engine

Air Cooled

Excessive heat is absorbed by air that is circulated around FINNED cylinders

Liquid Cooled

COOLANT circulated through COOLANT JACKETS and absorbs excess heat of the engine

DETERIORATED HEAD GASKET

WARPED OR CRACKED HEAD

LEAKING OIL COOLER

Contamination for Liquid Cooled is caused by:

Coolant System

Mixture of antifreeze and water that lowers the FREEZING POINT and RAISES THE BOILING POINT

COOLING SYSTEM PRESSURE TEST (Pressure Tester)

A cooling system internal leak can be confirmed by a :

1. Ethylene Glycol- TOXIC; Not environmentally safe

2. Propylene Glycol- NON-TOXIC; environmentally safe

Types of Antifreeze

1. PRESSURE VALVE

2. VACUUM VALVE

Parts of the Pressure Cap

Pressure Valve

Improve cooling efficiency (ICE) and prevents loss of coolant

Valve held against the seat in the FILLER NECK by spring

Vacuum Valve

Valve held against seat in the BOTTOM of pressure relief valve by a spring

Overflow Tank

A tank the serves as a RECEPTACLE for the coolant

Radiator

Positioned to receive maximum flow of air to DISSIPATE HEAT, which the coolant has absorbed from the engine

Upper Tank

Core

Lower Tank

Parts of a Radiator

Thermostat

Temperature sensitive; used to REGULATE COOLED FLOW into the RADIATOR

CLOSED = COLD

OPEN = WARM

By-Pass Port

Allows coolant to circulate through the engine when the thermostat is closed

Coolant Pump

DRIVEN BY A BELT from the engine and CIRCULATES COOLANT through the engine and cylinder head

Cooling Fan

CREATES AIRFLOW through radiator

Temperature Indicator

Provides INDICATION of engine operating temperature

*Vaper Pressure

*Electrical

REFRACTO-METER - Measures FREEZING POINT

PRESSURE TESTER - Utilized to PRESSURIZE

Maintenance Meters