ENGINE COOLING SYSTEM

Purpose Keep engine at its most efficient

temperature In combustion process the temperature

of gases is 2200°c Coming to walls of cylinder it is 180 -

260°c This temperature should maintain More heat should not absorb by cooling.

up to 35% of heat

Types of Cooling Air cooling Liquid cooling

Air cooled Engine Metal fine are extended to cylinder walls Engine exposed to air Shrouds and fans are used in some

engines Engines are open not grouped

Water Cooled Engines Coolant circulate around cylinder walls It takes the heat by convection process Coefficient of heat transfer is higher in

liquids Coolant is a mixture of water and

antifreeze. (Normally 40/60 mixture)

How it Works:

Liquid Cooled Systems - A pressurized closed circulation systemLiquid Cooled Systems - A pressurized closed circulation system

Parts of a Liquid Cooling System

Radiator & Pressure Cap

Fan & Belt Coolant Pump Water Jackets Thermostat Hoses Coolant

Water jackets Open space between outside and inside

walls of cylinder The coolant circulates freely around

engine hot spots It includes valve seats and guides and

upper parts of cylinder where piston and rings slides

Water jackets

Water pump Impeller type centrifugal pumps Placed at front end of cylinder block and

back to radiator It can circulate 28,390 lit of coolant per

hour

It consist inlet, outlet, impeller, bearings and seals

Water Pump

Engine Fan To pull air through radiator It improves cooling at slow speeds Four to six blades, shrouds Variable speed fan Flexible blade fan Electric fans

Radiator Heat exchanger device It holds large volume coolant in close

contact with large amount of air Cores and pipes Inlet tank and sink Down flow and cross flow

Expansion tanks Separate plastic reservoir Recovery tank Connected to over flow Coolant in engine is expands…contrasts Surge tank An advantage to the use of an expansion

tank is that it eliminates almost all air bubbles from the cooling system. Coolant without bubbles absorbs heat better.

Transmission oil coolers

Thermostat Thermostatic device Wax pellet 85 to 90°c It is placed at passage from cylinder

head to upper tank of radiator

Radiator Pressure cap Sealing and pressurizing

Anti Freeze Solutions An antifreeze is a chemical additive which

lowers the freezing point of a water-based liquid

Lowers galvanic corrosion Maintain small viscosity to water methanol (methyl alcohol) propylene glycol 5% additives sodium silicate, disodium phosphate, sodium

molybdate, sodium borate, and dextrin dye (commonly a green, red, orange, yellow,

or blue fluorescent)

Temperature indicator Balancing coil gauge Bimetallic thermostat gauge Indicator light