Question 1

Technician A says that oil pumps are all negative displacement types. Technician B says that many oil pumps are driven by the front of the crankshaft. Who is correct?
A) A only
B) B only
C) Both A and B
D) Neither A nor B

Accepted Answer

Technician B is correct. While positive displacement oil pumps do exist, many oil pumps are driven by the front of the crankshaft.

Question 2

What part is attached to the cooling system and designed to warm the passenger compartment?

Accepted Answer

The answer of What part is attached to the cooling...

Question 3

Which PCM input sensor measures the pressure in the intake manifold?
A) MAF sensor
B) MAP sensor
C) TP sensor
D) ECT sensor

Accepted Answer

The MAP sensor (Manifold Absolute Pressure sensor) measures the pressure in the intake manifold and sends that signal to the PCM to determine engine load and fuel injection timing. The MAF sensor (Mass Air Flow sensor) measures the amount of air entering the engine, the TP sensor (Throttle Position sensor) measures the position of the throttle, and the ECT sensor (Engine Coolant Temperature sensor) measures the temperature of the engine coolant.

Question 4

Cooling systems are being discussed. Technician A says that removing the radiator cap should only be done when the engine is cold. Technician B says that most cooling systems are filled with a mix of 50/50 antifreeze to water. Who is correct?
A) A only
B) B only
C) Both A and B
D) Neither A nor B

Accepted Answer

Technician A is correct, as removing the radiator cap when the engine is hot can cause pressurized hot coolant to spray out and burn. Technician B is also correct, as the typical recommended ratio for antifreeze to water in a cooling system is 50/50.

Question 5

A car has a no-crank situation. The starter motor spins, but the engine does not rotate. What is the most likely cause?
A) a hydrostatic lock
B) a dead battery
C) a defective starter drive
D) a cracked crank pulley

Accepted Answer

If the starter motor is spinning, but the engine is not rotating, it is likely that there is an issue with the starter drive. The starter drive is responsible for engaging with the flywheel and turning the engine over. If it is defective, it will not be able to do this. A hydrostatic lock or a cracked crank pulley would prevent the engine from turning at all, while a dead battery would not cause the starter motor to spin.

Question 6

What component helps the engine to heat up to operating temperature as quickly as possible?

Accepted Answer

The answer of What component helps the engine to heat...

Question 7

As coolant temperature increases, the resistance of the typical NTC (Negative Temperature Coefficient) engine coolant temperature sensor:
A) Decreases
B) Increases
C) Does not change
D) None of the above

Accepted Answer

NTC sensor's resistance decreases as the temperature increases.

Question 8

What is used with chemical dye to aid in finding external oil leaks?

Accepted Answer

The answer of What is used with chemical dye to...

Question 9

Where are the most common locations for oil leakage?

Accepted Answer

The answer of Where are the most common locations for...

Question 10

How do OHV engines typically deliver pressurized oil to the upper part of the engine and valvetrain?

Accepted Answer

The answer of How do OHV engines typically deliver pressurized...

Question 11

The cetane rating of diesel fuel is an indication of:
A) How quickly the fuel burns
B) The sulfur content
C) The percentage of water content
D) How easily the fuel ignites

Accepted Answer

The cetane rating of diesel fuel is a measure of how easily the fuel will ignite, which in turn affects combustion efficiency and engine performance. A higher cetane rating indicates that the fuel will ignite more easily and completely, resulting in better overall performance.

Question 12

At sea level, what is the boiling point of water written in Fahrenheit and Celsius?

Accepted Answer

The answer of At sea level, what is the boiling...

Question 13

All of the following API classifications of oil are currently in use EXCEPT ____.
A) SM
B) SN
C) SL
D) SK

Accepted Answer

There is no current API classification of oil with the designation "SK". The most recent classifications are SM, SN, and SL.

Question 14

Technician A says that AGM batteries should only be tested using a conductance tester. Technician B says that AGM batteries should only be charged using a special charger. Who is correct?
A) A only
B) B only
C) Both A and B
D) Neither A nor B

Accepted Answer

The answer of Technician A says that AGM batteries should...

Question 15

Technician A says that batteries can be cleaned with a baking soda and water solution. Technician B says that a baking soda and water solution may be used if a battery failed the battery case test. Who is correct?
A) A only
B) B only
C) Both A and B
D) Neither A nor B

Accepted Answer

Both Technicians A and B are correct. Batteries can be cleaned with a baking soda and water solution to remove any corrosion that may have formed on the terminals. Additionally, if a battery fails the battery case test, a baking soda and water solution may be used to clean any corrosion that may be causing the problem.

Question 16

Technician A says gasoline that is used in year-round warm climates has the same volatility as a fuel blended for use in colder winter climates. Technician B says a fuel with too high of a volatility in warm climates can cause vapor lock.
A) Technician A
B) Technician B
C) Both A and B
D) Neither A nor B

Accepted Answer

Technician A is incorrect because fuel blended for use in colder winter climates typically has a higher volatility to aid in cold starting. On the other hand, fuel blended for use in warmer climates typically has a lower volatility to minimize evaporative emissions. Therefore, gasoline used in year-round warm climates has a lower volatility compared to fuel blended for winter use. 
Technician B is correct because fuel with high volatility in warm climates can cause vapor lock, which occurs when the fuel cannot flow smoothly from the tank to the engine due to the formation of bubbles in the fuel line. This is why fuel with lower volatility is recommended for use in warmer climates to reduce the risk of vapor lock.

Question 17

At the normal service interval for an oil change, the technician notices the oil level reads just below the normal level on the dipstick before beginning to drain the oil. Technician A says that all engines will consume some amount of oil within the normal service interval. Technician B says that the technician should check any TSBs related to oil consumption and inform the customer. Who is correct?
A) A only
B) B only
C) Both A and B
D) Neither A nor B

Accepted Answer

Both technicians are correct. Technician A is correct that it is normal for engines to consume some amount of oil within the service interval, especially as the engine gets older. Technician B is also correct that the technician should check for any TSBs related to oil consumption and inform the customer, as there may be a known issue with the engine that needs to be addressed.

Question 18

Technician A says engine cooling fans are only necessary when the vehicle is moving slowly or stopped. Technician B says modern aerodynamic shapes have increased the need for operating the cooling fan. Who is correct?
A) Technician A
B) Technician B
C) Both A and B
D) Neither A nor B

Accepted Answer

Technician B is correct, as modern aerodynamic shapes create less air flow through the engine compartment when the vehicle is in motion, so the cooling fan needs to operate more frequently to keep the engine at a safe operating temperature. Technician A is incorrect, as cooling fans are necessary at all speeds, as airflow through the radiator is reduced when the vehicle is traveling at highway speeds.

Question 19

While performing a starter draw test on a car, it is noted that the starter has a slow cranking speed and a lower than normal amperage draw. What is the most likely cause?
A) worn starter brushes
B) worn starter bushings
C) incorrect ignition timing
D) hydrolocked engine

Accepted Answer

A slow cranking speed and lower than normal amperage draw are both indicative of worn starter brushes. Worn starter bushings might also cause a slow cranking speed, but they would not typically affect the amperage draw. Incorrect ignition timing would not affect the starter directly, while a hydrolocked engine would prevent the starter from cranking at all.

Question 20

All of the following could cause low oil pressure during a pressure test EXCEPT ____.
A) excessive bearing clearance
B) gas dilution
C) oil pump wear
D) tight valve adjustment

Accepted Answer

Tight valve adjustment would not cause low oil pressure during a pressure test. Excessive bearing clearance, gas dilution, and oil pump wear can all contribute to low oil pressure.

Quiz 4: Engine Operating Systems

Technician A says that oil pumps are all negative displacement types. Technician B says that many oil pumps are driven by the front of the crankshaft. Who is correct?

What part is attached to the cooling system and designed to warm the passenger compartment?

Which PCM input sensor measures the pressure in the intake manifold?

Cooling systems are being discussed. Technician A says that removing the radiator cap should only be done when the engine is cold. Technician B says that most cooling systems are filled with a mix of 50/50 antifreeze to water. Who is correct?

A car has a no-crank situation. The starter motor spins, but the engine does not rotate. What is the most likely cause?

What component helps the engine to heat up to operating temperature as quickly as possible?

As coolant temperature increases, the resistance of the typical NTC (Negative Temperature Coefficient) engine coolant temperature sensor:

What is used with chemical dye to aid in finding external oil leaks?

Where are the most common locations for oil leakage?

How do OHV engines typically deliver pressurized oil to the upper part of the engine and valvetrain?

The cetane rating of diesel fuel is an indication of:

At sea level, what is the boiling point of water written in Fahrenheit and Celsius?

All of the following API classifications of oil are currently in use EXCEPT ____.

Technician A says that AGM batteries should only be tested using a conductance tester. Technician B says that AGM batteries should only be charged using a special charger. Who is correct?

Technician A says that batteries can be cleaned with a baking soda and water solution. Technician B says that a baking soda and water solution may be used if a battery failed the battery case test. Who is correct?

Technician A says gasoline that is used in year-round warm climates has the same volatility as a fuel blended for use in colder winter climates. Technician B says a fuel with too high of a volatility in warm climates can cause vapor lock.

Technician A says engine cooling fans are only necessary when the vehicle is moving slowly or stopped. Technician B says modern aerodynamic shapes have increased the need for operating the cooling fan. Who is correct?

While performing a starter draw test on a car, it is noted that the starter has a slow cranking speed and a lower than normal amperage draw. What is the most likely cause?

All of the following could cause low oil pressure during a pressure test EXCEPT ____.