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Learn about the components and functions of the cooling system in your vehicle, from the water pump and cooling fan to the radiator and thermostat. Discover how these parts work together to regulate engine temperature and ensure optimal performance.
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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