Automotive Technology: Coolants

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Questions and Answers

What is a key characteristic of propylene glycol-based coolants compared to ethylene glycol-based coolants?

It should not be mixed with ethylene glycol. (correct)

It is more harmful to animals.

It is used as factory-fill coolant.

It is sweet tasting.

Which type of coolant is known for being phosphate-free?

Traditional coolant

Hybrid organic acid technology (HOAT)

Mineral-based coolant

Organic acid technology (OAT) (correct)

What does the abbreviation HOAT stand for?

Hydroxy organic acid technology

Hydrocarbon organic acid technology

Hybrid organic acid technology (correct)

High odor acid technology

Which coolant type is specifically mentioned as not compatible with both IAT and OAT coolants?

Hybrid organic acid technology (HOAT) Signup and view all the answers

Which property makes phosphate-free coolant more environmentally friendly?

Zero phosphates Signup and view all the answers

What does the thermostat control in an automobile cooling system?

Minimum engine operating temperature Signup and view all the answers

Why should a person not rely solely on color to identify coolant type?

Colors can be misleading and vary based on manufacturer. Signup and view all the answers

What is the effect of coolant compatibility on vehicle maintenance?

Incompatible coolants can cause engine damage. Signup and view all the answers

What is the primary function of the water pump in a vehicle's cooling system?

To move the coolant through the cooling system Signup and view all the answers

Which component is typically driven by the crankshaft in the cooling system?

The water pump Signup and view all the answers

What type of pump is used in vehicle cooling systems?

Centrifugal pump Signup and view all the answers

What is the role of the radiator in an automotive cooling system?

To transfer heat from the coolant to the air Signup and view all the answers

What materials are commonly used for the tanks attached to the radiator core?

Plastic or aluminum Signup and view all the answers

What component in the cooling system may have multiple units in some vehicles?

The thermostat Signup and view all the answers

How is the water pump usually mounted in a vehicle's cooling system?

Directly to the engine block Signup and view all the answers

Which part of the radiator is primarily responsible for exposing coolant to air for heat exchange?

The core Signup and view all the answers

What effect does lime and dirt buildup in coolant passages have on engine performance?

Insulates water jacket walls Signup and view all the answers

Why is it important to inspect all cooling system hoses?

To identify and replace damaged components Signup and view all the answers

How should coolant be added to an engine if the level is too low?

At the coolant recovery tank cap Signup and view all the answers

What does a coolant hydrometer measure?

Freezing point of coolant Signup and view all the answers

What potential danger exists when opening the cap on a warm cooling system?

Pressurized hot coolant can explode Signup and view all the answers

What should be checked in the radiator during a cooling system inspection?

Signs of dirt, bugs, and leaks Signup and view all the answers

How does a refractometer assess coolant condition?

By analyzing light passage through the sample Signup and view all the answers

What is the recommended action if the radiator shows signs of leaks?

Repair or replace the radiator Signup and view all the answers

What is essential for replacement radiator hoses?

They must have the correct diameter, length, and shape. Signup and view all the answers

What should be done first when replacing a hose?

Drain the coolant system below the level being worked on. Signup and view all the answers

What is the purpose of dipping the ends of a new hose in coolant before installation?

To lubricate the ends for easier fitting. Signup and view all the answers

What must be done after positioning the hose on its fittings?

Slide the clamps to about 6.4 mm from the end of the hose. Signup and view all the answers

What type of clamps can be used for thermoplastic hoses?

Heat-sensitive thermoplastic clamps. Signup and view all the answers

When replacing a thermostat, what must always be replaced along with it?

The gasket sealing the thermostat. Signup and view all the answers

What should be done to the mating surfaces of the thermostat housing and block before installation?

They must be clean and free of old gasket material. Signup and view all the answers

Why is changing the engine's coolant part of preventive maintenance?

To prevent the coolant from breaking down chemically. Signup and view all the answers

What happens to the cooling fan motor when the engine coolant temperature exceeds approximately 110°C (230°F)?

The fan relay coil is energized. Signup and view all the answers

What type of fan has mostly replaced conventional belt-driven fans in late model vehicles?

12-volt motor-driven fans. Signup and view all the answers

Which feature allows the cooling fan to operate even when the vehicle is off?

Automatic engagement feature. Signup and view all the answers

What does the coolant temperature indicator usually consist of?

Temperature gauge and light. Signup and view all the answers

Where is a block heater typically installed?

In the water jacket. Signup and view all the answers

What happens to the relay contacts when engine coolant is below 101.6°C (215°F)?

The relay contacts remain open. Signup and view all the answers

What is the primary function of the electric cooling fan?

To lower engine coolant temperature. Signup and view all the answers

What must be done regularly for the cooling system of a vehicle?

Inspect and service it as a system. Signup and view all the answers

Study Notes

Coolants Overview

IAT (Inorganic Additive Technology) coolant is incompatible with new long-life coolants.
Propylene glycol-based coolants are less harmful than ethylene glycol but not suitable for factory-fill and must not be mixed with ethylene glycol.
Phosphate-free coolants, which are ethylene glycol-based and free of phosphates, are environmentally friendly and recommended by some manufacturers.
Organic Acid Technology (OAT) coolant is also environmentally friendly, phosphate and silicate-free, commonly recognized by the brand DEX-COOL.
Hybrid Organic Acid Technology (HOAT) is less abrasive to water pumps, used by Ford and Chrysler, and incompatible with IAT or OAT coolants.

Engine Cooling System Components

The thermostat regulates the engine's minimum operating temperature, while maximum temperature depends on engine output and cooling system efficiency.
The water pump, essential for circulating coolant, is typically driven by the crankshaft via belts and may feature a centrifugal design with rotating impellers.

Radiator Functionality

The radiator acts as a liquid-to-air heat exchanger, facilitating heat transfer from the engine coolant to the air.
The core of the radiator is composed of tubes and fins, maximizing heat exposure to air for efficient cooling.
Radiators typically have plastic or aluminum tanks attached for structural integrity.

Fan and Temperature Control

Modern vehicles often have 12-volt motor-driven cooling fans that reduce power consumption and noise compared to traditional belt-driven fans.
The engine cooling fan operates based on coolant temperature; it activates when the temperature exceeds approximately 110°C (230°F).

Coolant Warning Systems

A coolant temperature indicator alerts drivers of overheating through gauges or lights, relying on temperature sensors in the water jacket.
Block heaters can be installed in vehicles to prevent freezing by warming the coolant.

Cooling System Maintenance

Inspect all cooling system hoses for leaks or damage and replace any that show wear.
Radiators must be checked for leaks, dirt buildup, and blockages to ensure optimal performance.
Coolant levels should be monitored at the recovery tank, maintaining levels between LOW and FULL indicators.

Coolant Quality Testing

A coolant hydrometer measures antifreeze concentration and freezing point of the coolant.
A refractometer provides precise coolant condition assessments by evaluating light refraction through the fluid sample.

Hose and Thermostat Replacement

When replacing hoses, ensure correct diameter and shape, and lubricate the ends with coolant to ease installation.
Replace thermostat gaskets to avoid leaks and ensure a clean mating surface when installing a new thermostat.

General Safety Precautions

Always allow the cooling system to cool before opening caps to prevent pressurized hot coolant from escaping.
Regular coolant changes are crucial to prevent chemical breakdown and maintain system efficiency.

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Description

This quiz covers the key concepts of automotive coolants, specifically focusing on the compatibility of IAT coolant with newer long-life coolants and the characteristics of propylene glycol-based coolants. Understand the differences and applications of these important substances in vehicle maintenance.