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THE COOLING SYSTEM. Purpose. To regulate the engines internal temperature To remove excess heat from the engine To provide heat to the passenger compartment. The Water Pump. Centrifugal-type, rotates faster than crank, up to 10,000 gal. per hour
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Purpose • To regulate the engines internal temperature • To remove excess heat from the engine • To provide heat to the passenger compartment
The Water Pump • Centrifugal-type, rotates faster than crank, up to 10,000 gal. per hour • Pulley driven, belt, chain drive or direct drive
The Cooling Fan • Provides air flow with vehicle stopped • Provides increased air flow at low RPM or vehicle speeds • Belt driven or Electric
Belt Driven Cooling Fan Clutch • Limits actual fan speed no more than 2000 rpm • Engaged at low speeds • Disengaged at high speeds • Thermostatic (temp. sensitive)
Flex Blade Fan • Fan blades flatten out at high speeds, reducing noise, increasing horse power
Electric Cooling Fan • Electric – 12v DC motor driven fan • Controlled in several ways • Engine coolant temp (ECT) switch • A/C select switch • PCM controlled based on various inputs • Fan turns on/off at specific temps.
Electro-Viscous Fan Clutch • PCM Controlled fan speed • Sensors monitored to control speed: • ECT, A/C request, VSS, IAT, Trans Fluid Temp, AAT • Solenoid controls fluid flow, regulating fan speed • Internal hall effect sensor monitors fan speed
The Radiator • Transfers heat from coolant to the atmosphere • Two types – Vertical & cross flow • Aluminum, brass, copper core; brass, copper or plastic tanks • Air movement through radiator created by a mechanical fan or by vehicle movement (ram air) dissipates heat
Radiator Pressure Cap • Regulates pressure in the cooling system • Rated in psi – always replace with same rating • Pressure valve – allows liquid or vapor to escape • Vacuum valve – as system cools, coolant can reenter the system
The Thermostat • Regulates engine coolant temperature • Rated in degrees – 195 degrees most common • Solid Expansion design – wax pellet expands as temp increases, valve begins opening at rating & is completely open within 20 degrees
Coolant • Provides freeze & boil over protection, corrosion prevention & good heat transfer • Ethylene Glycol based – recommended 50/50 mixture with water, poisonous • Dex-Cool – used by GM, 5 year 150,000 mile protection, doesn’t contain silicate & phosphate additives
The Heater Core • Small size radiator located in the dash, coolant circulates through it. A blower motor passes fresh air over it, heat transfers to the cooler air and into the cabin • Many vans & SUV have rear heating units