Automotive Algebra

Maintaining the cooling system Using Algebra for a simple

solution

Joe Agruso ,Xochitl Molina

What happens if you don’t maintain the cooling system

Examples of Overheating *80% of engine failure is a direct result of

cooling system failure

Components of the cooling system

Operation of the Cooling System

• The cooling system is made up of the passages inside the engine block and heads, a  water pump to circulate the coolant, a thermostat to control the temperature of the coolant, a radiator to cool the coolant, a radiator cap to control the pressure in the system, and some plumbing consisting of interconnecting hoses to transfer the coolant from the engine to radiator and also to the car's heater system where hot coolant is used to warm up the vehicle's interior on a cold day.

• A cooling system works by sending a liquid coolant through passages in the engine block and heads.  As the coolant flows through these passages, it picks up heat from the engine.  The heated fluid then makes its way through a rubber hose to the radiator in the front of the car.  As it flows through the thin tubes in the radiator, the hot liquid is cooled by the air stream entering the engine compartment from the grill in front of the car.  Once the fluid is cooled, it returns to the engine to absorb more heat.  The water pump has the job of keeping the fluid moving through this system of plumbing and hidden passages.

Boiling point of Water

• The boiling point of water is 212 degrees Fahrenheit, or 100 degrees Celsius. The speed at which the water molecule of H2O is moving causes the temperature in water to increase and eventually boil and evaporate.

212 degrees Fahrenheit, or 100 degrees Celsius

The boiling temperature of water is 212 degrees Fahrenheit

• Use formula F= 9/5 C +32 to convert to Celsius

• 212 =9/5 C + 32• -32 - 32• 180 =9/5 C• x5• 900/9 = 100 C=100

The boiling point of water is 100 degrees Celsius

• Now, convert 80 Fahrenheit to Celsius

• O.556 (f-32)=26.7 C

• A thermostat is calibrated to open up at 190 Fahrenheit what is the temperature in C

• C=5/9(f-32) or C=.556(f -32)

Reducing the boiling point of antifreeze using pressure

• Pressure cap and reserve tank As coolant gets hot, it expands.  Since the cooling system is sealed, this expansion causes an increase in pressure in the cooling system, which is normal and part of the design.  When coolant is under pressure, the temperature where the liquid begins to boil is considerably higher.  This pressure, coupled with the higher boiling point of anti-freeze, allows the coolant to safely reach temperatures in excess of 250-260 degrees.

• The radiator pressure cap is a simple device that will maintain pressure in the cooling system up to a certain point.  If the pressure builds up higher than the set pressure point, there is a spring loaded valve, calibrated to the correct Pounds per Square Inch (psi), to release the pressure.

Pressure Tests

Test operation of radiator cap and test cooling system for leaks

• Testing the cooling system is a simple process to determine where a leak is located.  This test is only performed after the cooling system has cooled sufficiently to allow you to safely remove the pressure cap.  Once you are sure that the cooling system is full of coolant, a cooling system pressure tester is attached in place of the radiator cap.  The tester is than pumped to build up pressure in the system.  There is a gauge on the tester indicating how much pressure is being pumped.  You should pump it to the pressure indicated on the pressure cap or to manufacturer's specs.

Demonstrate the use of a Pressure tester a vehicle is provided with a

concern of overheating.

• After visual inspections you have found a leak but cannot determine where it is located so you hook up a cooling system pressure tester to isolate the leak.

• You found a loose hose clamp from the heater core inlet hose and have secured the clamp

Scenario

• Your engine is operating at 242 degrees Fahrenheit. The boiling point of water in a tea pot is 212 degrees Fahrenheit, and for each 1 pound of pressure the boiling point is increased by 3 degrees what is the safe operating temperature of your engine?

Antifreeze

• Keeping a proper coolant mixture is vital to your car's health. Antifreeze should be close to a 50 percent mixture, depending on your climate and driving conditions. But how are you supposed to know whether your coolant mixture is right for you and your car? You can test your coolant mixture easily with an inexpensive coolant mixture tester that can be bought at any auto parts store.

Testing Antifreeze

Hydometer readings

• Check the freeze point scale on the hydrometer. It should read 34 degrees Fahrenheit or below. A higher temperature indicates the cooling system requires flushing. Check the boiling point on the hydrometer. It should read 265 degrees Fahrenheit or higher. A lower boiling point indicates that the cooling system requires flushing.

After visual inspections you see that nothing seems to be wrong with the cooling system. As coolant temperature increases, so does the pressure in the cooling system. This pressure is regulated by the radiator cap. Each one pound of increased pressure raises the boiling point by 3°F.

Translate the following statement as a ratio “each one pound of increased pressure raises the boiling point by 3°F”.

If your engine is operating at 242°F and your radiator pressure is 15 psi, by how many degrees has boiling point of the cooling system increased?

What is the safe operating temperature of your vehicle?

Write down the algebraic steps taken to solve for number 3.

You notice your vehicle has started to overheat. You have taken your vehicle to the repair shop and they have come back with a NPF.

Therefore, you decide to take a look at the coolant using a hydrometer.

Part A)Test the vehicle coolant using the hydrometer in Celsius (Round to the nearest tenth place)

Part B) Covert your answer from part A to Fahrenheit.

Naked Math See pdf

Converting Fahrenheit to Celsius Using:

F= 9/5 C +32

• 110 °F = ____°C 69 °F = ___°C

• 209 °F = ___°C 62 °F =___ °C

• 72 °F = ___ °C 90 °F = ___°C