Paper, Pen or Pencil for notes Cooling System Fundamentals You will need: Paper, Pen or Pencil for notes

Contents Cooling system functions Cooling system operation Cooling system types Basic cooling system Closed and open cooling systems Cooling system instrumentation Antifreeze Block heater

Cooling System Functions

Cooling System Functions Helps Engine Reach Operating Temperature Quickly Maintains Constant Engine Operating Temperature Removes Excess Engine Heat Provides Heat For Warming the Passenger Area

Helps Engine Reach Operating Temperature Quickly Advantages of Rapid Engine Warm-up: Improved combustion (better fuel vaporization) Reduced part wear Less oil contamination Increased fuel economy Reduced emissions

Advantages of Maintaining a Proper Operating Temperature Ensures Proper Combustion Minimum Emissions Maximum Performance Maintains Optimum Fuel Economy

Maintains Constant Operating Temperature Thermostat opens and closes to Maintain Temp 160 ºF to 195 ºF (Depending on thermostat) When an engine warms to operating temperature parts expand and rapid warm-up reduces part wear Ensures that clearances are correct

Removes Excess Engine Heat On Modern Vehicles, Typical Combustion Temperatures can reach 4500 ºF (2500 ºC) This is hot enough to melt metal parts Cooling system removes excess heat which can cause major engine damage!

Air-cooled Engine This air-cooled engine has had the cooling fan and shrouding removed for better viewing. The shrouding directs the air-flow around the cylinders

Cooling Fan & Shrouding Removed for better view Cooling System Types Two common types: air cooling liquid cooling Cooling Fan & Shrouding Removed for better view

Air Cooling Versus Liquid Cooling

Air Cooling Systems Large cylinder cooling fins and outside air remove excess heat Cooling fins increase the surface area of the metal around the cylinder This allows enough heat transfer to the outside air Plastic or metal shrouds duct air onto and around the cylinder fins

Liquid Cooling Systems Circulate coolant through the water jackets Combustion heat is transferred to the coolant Cooling system carries it out of the engine Hot coolant flows into the radiator where heat is removed Cooled coolant flows back into engine to repeat this process

Liquid Cooling Advantages Precise temperature control Less temperature variation Reduced emissions Improved heater operation

Heat is transferred to cylinder wall, into coolant and carried away Liquid Cooling Heat is transferred to cylinder wall, into coolant and carried away

Conventional Coolant Flow Hot coolant flows from the cylinder head to the radiator After being cooled in the radiator, the coolant flows back into the engine block

Reverse Flow Cooling Cool coolant enters the head and hot coolant exits the block to return to the radiator Helps keep a more uniform temperature throughout the engine Found on high-performance engines

Basic Cooling System Components: Radiator Radiator Hoses Fan Thermostat Water Pump

Transfers coolant heat to the outside air Radiator Transfers coolant heat to the outside air

Radiator Types Vertical Flow Cross Flow

Radiator Hoses and Heater Hoses

Hoses Radiator Hoses Heater Hoses Carry coolant between the engine water jackets and the radiator Lower hose is exposed to water pump suction so a spring may prevent collapse Heater Hoses Carry hot coolant to the heater core Smaller diameter than radiator hoses

Three basic types of hose clamps

Two basic types of radiator hoses

Radiator Fan Draws air through the radiator and cools off the hot coolant passing through it.

Thermostat Maintains a constant engine temperature Helps engine reach operating temperature quickly Senses coolant temperature and controls coolant flow through the radiator Reduces coolant flow on cold engine Increases coolant flow on hot engine

A temperature-sensitive valve Thermostat A temperature-sensitive valve

Thermostat Operation Cold engine Hot engine wax-filled pellet has contracted spring holds valve closed Hot engine when heated, pellet expands spring tension is overcome valve opens

Thermostat Operation A. Cold engine B. Hot engine

Thermostat Operation Cold engine Hot engine

Water Pump A ribbed belt powers this pump which pumps coolant throughout the engine. Crank pulley Water pump pulley Impeller Ribbed belt

Impeller Pump Coolant is thrown outward by centrifugal force, producing suction in the center of the pump housing. Straight impeller blades use less energy to operate.

Water Pump Cutaway Water Pump Parts

Radiator Types Vertical Flow Cross Flow Tanks on top and bottom Tanks on both sides

Transmission Oil Cooler Often placed in the radiator on cars with automatic transmissions Prevents transmission fluid from overheating

Transmission Oil Cooler Small tank inside one of the radiator tanks

Water Pump Parts Water pump housing -Iron or aluminum casting that forms the main body of the pump. Water pump impeller -Disk with fan-like blades, the impeller spins and produces pressure and flow. Water pump shaft -Steel shaft that transmits the turning force from the hub to the impeller. Water pump seal -Prevents coolant leakage between pump shaft and pump housing. Water pump bearing -Plain or ball-bearings that allow the pump shaft to spin freely in housing. Water pump gasket -Fits between the water pump and the engine to prevent leakage. Water pump hub -Provides a mounting place for the belt, pulley, and fan.

Radiator Hoses and Clamps Radiator hoses –Carry coolant between the engine water jackets and the radiator. Flexible hose –Has an accordion shape and can be bent to different angles. Molded hose –Manufactured in a special shape, with bends to clear the cooling fan and other parts. Heater hoses –Small-diameter hoses that carry coolant to the heater core. Hose spring –Frequently used in the lower radiator hose to prevent the hose from collapsing. Worm-drive hose clamps –Uses a worm gear that engages slots in the clamp strap to allow tightening around the hose. Hose clamps –Hold the radiator hoses and heater hoses onto their fittings

Radiator Cap Seals the radiator Pressurizes the system Relieves excess pressure Allows coolant flow between the radiator and the coolant reservoir

Radiator Cap

Radiator Cap Vacuum Valve Opens to allow flow back into the radiator when the coolant temperature drops. Without this valve the coolant would not flow back into the radiator and the radiator would become low on coolant and the engine would overheat.

Radiator Cap Pressure Valve Spring-loaded disk Normally, water boils at 212 ºF (100 ºC) For each pound of pressure increase, boiling point goes up about 3 ºF (1.6 ºC) Typical pressure: 12–16 psi raises boiling point to 250–260 ºF (121–127 ºC)

Closed and Open Cooling Systems Closed cooling system Uses an Expansion Tank Overflow tube is routed into reservoir tank Open cooling system Allows excess coolant to leak onto the ground

Pressure Cap Operation Hot engine Cold engine

Cooling System Fans Pull air through the core of the radiator Increase volume of air through the radiator Driven by fan belt or electric motor

High rpm cause blades to flex, reducing blowing action Flex Fan High rpm cause blades to flex, reducing blowing action

Fluid Coupling Fan Clutch Filled with silicone-based oil Slips at higher rpm

Thermostatic Fan Clutch Bimetal spring controls clutching action Cold—clutch slips Hot—clutch locks

Electric Cooling Fans Provide cooling with an electric motor and a thermostatic switch Use A small direct current motor to operate the cooling fan Common on transverse-mounted engines Save energy and increase cooling efficiency Fans only function when needed

Electric Fan Operation Cold engine Hot engine

PCM-Controlled Fans When cold, ECM does not energize fan relays After warm-up, ECM feeds current to the fan relay coils, closing relay contacts High current flows to fans

Ensures that the fan pulls air through the radiator core Radiator Shroud Ensures that the fan pulls air through the radiator core

Modern Cooling Systems Use thermostats that are 195°F and higher (which is higher than older vehicles, 160°F-180°F) Advantages Engines that run higher coolant temperatures: run smoother with more power run more efficiently and use less fuel burn much cleaner heaters/defrosters work better

Thermostat Operation Cold engine – Thermostat is closed no coolant flows through the radiator

Bypass Valve Permits some circulation through the engine when the thermostat is closed

Blocks off the bypass at operating temperature Bypass Thermostat Blocks off the bypass at operating temperature Impeller Water pump drive pulley Water pump housing Thermostat Main flow Flow to radiator Bypass spring Bypass flow Main spring

Thermostat Jiggle Valve The valve allows trapped air to escape when the cooling system is flushed or opened for repairs. The trapped air is a serious problem which could prevent the thermostat from opening and create hot spots with erratic sensor behavior. The air is hard to remove without the valve. Since air rises up in water, the valve should be installed in the 12 o'clock position.

Temperature Warning Light When coolant becomes too hot, a temperature sending unit (switch) in the block closes, completing a circuit and the warning light comes on, letting the driver know there is a problem. Warning Light Circuit

Antifreeze Prevents winter freeze-up Prevents rust and corrosion Composed of ethylene glycol mixed with water Prevents winter freeze-up Prevents rust and corrosion Lubricates the water pump Raises the boiling point Lowers the freezing point

Antifreeze/Water Mixture A 50/50 mixture is most commonly used Lowers coolant freezing point to -34 ºF Raises the boiling point to 265 ºF

Protected with antifreeze Corrosion Protection Protected with antifreeze Water only

Block Heater Installation Aids engine starting in cold weather 120-volt heating element mounted in the block water jacket Common on diesel engines Block Heater Installation

Questions? Refer to Duffy textbook chapter 39 Scroll back through power-point Ask fellow student for help After following all the above steps, check with your instructor