Halderman ch020 lecture

© 2011 Pearson Education, Inc.All Rights Reserved

Automotive Technology, Fourth EditionJames Halderman

COOLANT

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ObjectivesObjectives

• The student should be able to:– Prepare for ASE Engine Repair (A1)

certification test content area “D” (Lubrication and Cooling Systems Diagnosis and Repair).

– Describe the various types of antifreeze coolants.

– Discuss how to store, recycle, and discard used coolant.

– Discuss how to test coolant.

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COOLANT COOLANT FUNDAMENTALSFUNDAMENTALS

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Coolant FundamentalsCoolant Fundamentals

• Purpose of Coolant– Transfers heat from the engine to the

radiator– Protects the engine and the cooling system

from rust and corrosion

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• Purpose of Coolant– Prevents freezing in cold climates

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Figure 20-1 Graph showing the relationship of the freezing point of the coolant to the percentage of antifreeze used in the coolant.

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• Freezing/Boiling Temperatures– Freezing point increases as antifreeze

concentration increases – If the coolant boils, it vaporizes and does

not act as a cooling agent

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Figure 20-2 Graph showing how the boiling point of the coolant increases as the percentage of antifreeze in the coolant increases.

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• Coolant Consumption– All manufacturers recommend ethylene

glycol based coolant which contains• Ethylene glycol (EG): 47%

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glycol based coolant which contains• Water: 50%

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glycol based coolant which contains• Additives: 3%

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• The only difference among all original equipment coolants is the additives

• About 97% of all coolants are the same

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TYPES OF COOLANTTYPES OF COOLANT

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Types of CoolantTypes of Coolant

• Inorganic Acid Technology (IAT)– Conventional coolant that has been used

for over 50 years– Most conventional green antifreeze

contains inorganic salts

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Types of Coolant Types of Coolant

• Organic Acid Technology (OAT)– Ethylene glycol, but does not contain

silicates or phosphates– Color is usually orange

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• Organic Acid Technology (OAT)– DEX-COOL is one brand

• Developed by Havoline used by GM since 1996

?

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Figure 20-3 Havoline was the first company to make and market OAT coolant. General Motors uses the term DEX-COOL.

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• Hybrid Organic Acid Technology (HOAT)– Similar to OAT in that it uses organic acid

salts– HOAT coolants can be green, orange,

yellow, gold, pink, red, or blue

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• Hybrid Organic Acid Technology (HOAT)– HOAT coolants include:

• WW/Audi pink• Mercedes/Ford yellow• Ford yellow

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• Hybrid Organic Acid Technology (HOAT)– HOAT coolants include:

• Honda blue• European/Korean blue• Asian red

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• Phosphate Hybrid Organic Acid Technology (PHOAT)– Used in Mazda-based Fords (2008+)– Ethylene glycol based– Concentration: 55%

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• Phosphate Hybrid Organic Acid Technology (PHOAT)– Boiling point (with 15 PSI pressure cap):

270 ｡ F (132 ｡ C)– Freezing point: - 47 ｡ F (- 44 ｡ C)

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• Phosphate Hybrid Organic Acid Technology (PHOAT)– Color: Dark green– Embittered (so animals will not drink it)

?

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Figure 20-4 Coolant used in Fords that use Mazda engines and in Mazda vehicles. It requires the use of a PHOAT coolant which is dark green.

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Figure 20-5 Not all embittered coolant is labeled embittered.

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• Universal Coolant– Usually a hybrid organic acid technology

(HOAT) with extended life and low-silicate, phosphate-free

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• Universal Coolant– Cannot meet the needs for engines

requiring a silicate-free formulation

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WATERWATER

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WaterWater

• Introduction – Water is half the coolant– Many vehicle manufacturers specify the

use of premix coolants only

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WaterWater

• Properties– Inexpensive– Efficient heat exchange fluid – Good specific heat capacity

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WaterWater

• Properties– The boiling point is 212°F (100°C) (at sea

level)– The freezing point is 32°F (0°C)

??

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COOLANT FREEZING/COOLANT FREEZING/BOILING BOILING

TEMPERATURESTEMPERATURES

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Coolant Freezing/Boiling Coolant Freezing/Boiling TemperaturesTemperatures

• Freezing Point– Differs from the freezing point of pure

antifreeze or pure water• Pure water 32°F (0°C)

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antifreeze or pure water• Pure antifreeze 0°F (−18°C)

– Pure antifreeze is usually 95% ethylene glycol, 2% to 3% water, and 2% to 3% additives.

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antifreeze or pure water• 50/50 mixture −34°F (−37°C)

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antifreeze or pure water• 70% antifreeze/30% water −84°F (−64°C)

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• Boiling Point– Factor of mixture concentrations

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• Boiling Point– Boiling points at sea level

• Pure water 212°F (100°C)• 50/50 mixture 218°F (103°C) • 70/30 mixture 225°F (107°C)

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• Boiling Point– Boiling points with 15 PSI Pressure cap

• Pure water 257°F (125°C)• 50/50 mixture 265°F (130°C)• 70/30 mixture 276°F (136°C)

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COOLANT TESTINGCOOLANT TESTING

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Coolant Testing Coolant Testing

• Normal Coolant Tests include:– Visual inspection– Freeze/boiling point– pH– Coolant voltage

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• Hydrometer Testing– Measures the density of the coolant– Higher density indicated higher

concentration of antifreeze

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• Hydrometer Testing– Most hydrometers read the freezing and

boiling points – If the engine is overheating and the

hydrometer reading is near −50°F (−60°C), suspect that pure 100% antifreeze is present

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• Hydrometer Testing– Coolant should have a freezing point lower

than −20°F (−29°C) and a boiling point above 234°F (112°)

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(Include "Tech Tip" page 179.)(Include "Tech Tip" page 179.)

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Figure 20-6 Checking the freezing temperature of the coolant using a hydrometer.

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Coolant TestingCoolant Testing

• Refractometer– Tests the freezing point of coolant by

placing a few drops of coolant on the prism surface

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• Refractometer– Measures the extent to which light is bent

(refracted) – The refractive index is commonly used for

the following:• To identify or confirm the identity of a

sample coolant

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• Refractometer– The refractive index is commonly used for

the following:• To determine the purity of a coolant by

comparing its refractive index to the value for the pure substance

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• Refractometer– The refractive index is commonly used for

the following:• To determine the concentration of a solute

in a solution by comparing the solution’s refractive index to a standard curve

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Figure 20-7 Using a refractometer is an accurate method to check the freezing point of coolant.

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• pH– "Power of hydrogen"– Measure of acidity or alkalinity of a solution

• Less than 7 pH is considered acidic

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• pH– Measure of acidity or alkalinity of a solution

• Greater than 7 pH is considered alkaline

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• pH– Typical pH values for new coolant include:

• IAT: 9 to 10.5 new

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• pH– OAT: 7.5 to 8.5 new (G30 and G34

designations)– HOAT: 7.5 to 8.5 new (G05, G48, G11, or

G12 designation)

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• pH– PHOAT: 7.5 to 8.5 new– Either a test strip or a pH meter is used

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• pH– Used coolant pH readings are usually lower

than new coolant and range from between 7.5 and 10 for IAT and lower for used OAT, HOAT, and PHOAT coolants

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Figure 20-8 A meter that measures the actual pH of the coolant can be used for all coolants, unlike many test strips that cannot be used to test the pH of red or orange coolants.

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• Galvanic Activity– Flow of an electrical current as a result of

two different metals in a liquid, which acts like a battery

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Figure 20-9 Galvanic activity is created by two dissimilar metals in contact with a liquid, in this case coolant.

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• Electrolysis– Requires the use of an outside voltage

source– The source is usually due to a poor

electrical ground connection

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• Electrolysis– Electrical flow may cause metal to flow into

the coolant– Metal transfer can eat holes in a heater

core or radiator

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• Electrolysis– Electrolysis holes will usually start from the

inside and have a dark coloration

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• Testing for Galvanic Activity and Electrolysis– A voltmeter set to read DC volts is used

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• Testing for Galvanic Activity and Electrolysis– To test for galvanic activity or electrolysis,

perform the following:• Allow engine to cool and carefully remove

the radiator cap

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perform the following:• Set the voltmeter to DC volts and connect

the black meter lead to a good engine ground

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perform the following:• Place the red meter lead into the coolant

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perform the following:• Read the meter (if the voltage is above 0.5

V, this indicates excessive galvanic activity). Flush and refill the cooling system.

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perform the following:• To test for excessive electrolysis, start the

engine and turn on all electrical accessories, including the headlights on high beam

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perform the following:• Read the voltmeter (if the reading is higher

than 0.5 V, check for improper body ground wires or connections).

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• Test Strip Testing– Test strips can be used to check:

• Freeze point• Boiling point• Level of pH

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• Test Strip Testing– Compare the color on the strip to the colors

on the container– Fairly accurate, easy to use, and

inexpensive

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• Test Strip Testing– For best results, use test strips that are

new and have been stored in a sealed bottle

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Figure 20-10 A test strip can be used to determine the pH and percentage of glycol of the coolant. The percentage of glycol determines the freezing and boiling temperatures, as shown on the bottle that contains the test strips.

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COOLANTCOOLANTREPLACEMENT ISSUESREPLACEMENT ISSUES

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Coolant Replacement IssuesCoolant Replacement Issues

• Intervals– The interval for most new vehicles using

OAT or HOAT type coolant may be every five years or 150,000 miles (241,000 km), whichever occurs first

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• Intervals– Japanese brand vehicles usually have a

replacement interval of three years or 36,000 miles (58,000 km), whichever occurs first

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• Intervals– If coolant is changed from long life to

conventional IAT, the replacement interval needs to be changed to every two years or 24,000 miles (39,000 km), whichever occurs first

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• Passivation– Chemical reaction that takes place

between coolant additives and the metal that it protects

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• Passivation– Can take from a few days to a few weeks– Each chemical package does its own

passivation

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• Passivation– If you change chemical packages,

passivation has to start over– Experts do not recommend changing the

type of coolant used

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• Passivation– Always use recommended coolant

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• CAUTION: Most vehicle manufacturers warn that coolant should not be reused unless it is recycled and the acids restored. However, Mercedes lifetime coolant is very expensive, and according to Mercedes can be drained, filtered, and reused.