POSTAL AUTOMOTIVE
TECHNICIAN 2025/2026 EXAM 944
QUESTION AND ANSWER
1. The vibration damper on an auto engine is fastened to the ______.
• A) Camshaft
• B) Flywheel
• C) Crankshaft
• D) Transmission input shaft
,,answer,,,: C. Crankshaft
Rationale: The harmonic balancer (vibration damper) is mounted on the
front of the crankshaft to absorb torsional vibrations.
2. Most small gas engines use a _________ ignition system.
• A) Magneto
• B) Battery coil
• C) Electronic control unit (ECU)
• D) Distributorless
,,answer,,,: A. Magneto
Rationale: Small engines (lawnmowers, chainsaws) often use a magneto
system because it does not require a battery.
3. Icing occurs most often ______.
• A) On hot dry days
• B) On cool damp days
, • C) In freezing rain
• D) During high humidity only
,,answer,,,: B. On cool damp days
*Rationale: Carburetor icing is most common in cool, damp weather
(typically 30-50°F) where humidity freezes due to the temperature drop from
fuel vaporization.*
4. The function of the float in a carburetor is to ______.
• A) Meter air flow
• B) Close the needle valve
• C) Regulate idle speed
• D) Control the choke
,,answer,,,: B. Close the needle valve
Rationale: The float rises with the fuel level to close the needle valve,
stopping fuel flow once the bowl is full.
5. To improve stability when cornering manufacturers added a device to cars
called ______.
• A) Anti-roll bar
• B) Stabilizer bar
• C) Sway bar
• D) All of the above
,,answer,,,: D. All of the above
Rationale: "Stabilizer bar," "Sway bar," and "Anti-roll bar" all refer to the
same component designed to reduce body roll.
6. Adjustment of the rods on a car will affect ______.
• A) Camber
• B) Caster
• C) Toe-in
, • D) Steering angle
,,answer,,,: C. Toe-in
Rationale: Adjusting the tie rods changes the toe alignment (the difference in
distance between the front and rear of the front tires).
7. A restriction in the exhaust system is indicated on a vacuum gauge by a
______.
• A) Sudden drop to zero
• B) Gradual decrease in reading
• C) Fluctuating needle
• D) Steady increase in vacuum
,,answer,,,: B. Gradual decrease in reading
Rationale: As RPM increases, a restricted exhaust (clogged catalytic
converter) causes backpressure, which makes the vacuum reading slowly
drop rather than hold steady.
8. Disc brakes on a car have a distinct advantage over conventional drum
brakes in that they ______.
• A) Are cheaper to manufacture
• B) Fade less when hot
• C) Require less maintenance
• D) Last longer
,,answer,,,: B. Fade less when hot
Rationale: Disc brakes dissipate heat faster because the rotor is open to the
air, unlike drum brakes which trap heat inside the drum.
9. In a diesel engine, the fuel is ignited by the ______.
• A) Spark plug arc
• B) Glow plug
• C) Heat of compression
, • D) External flame
,,answer,,,: C. Heat of compression
Rationale: Diesel engines use compression ignition; air is compressed until
it reaches a high temperature, then fuel is injected and ignites
spontaneously.
10. Engine timing is generally set by using a ______.
• A) Dwell meter
• B) Multimeter
• C) Strobe light
• D) Vacuum gauge
,,answer,,,: C. Strobe light
Rationale: A timing light (strobe light) flashes when the #1 spark plug fires,
allowing the technician to view the timing marks on the harmonic balancer.
11. If an engine is operating for long periods of time at part throttle opening
the ______.
• A) Pistons will overheat
• B) Spark plugs will become covered with carbon
• C) Valves will stick
• D) Fuel mixture will lean out
,,answer,,,: B. Spark plugs will become covered with carbon
Rationale: Prolonged low-speed or idling operation leads to incomplete
combustion, resulting in carbon fouling of the spark plugs.
12. Leaking intake valve guides will cause ______.
• A) Low compression
• B) Excessive oil consumption
• C) Coolant in the oil
TECHNICIAN 2025/2026 EXAM 944
QUESTION AND ANSWER
1. The vibration damper on an auto engine is fastened to the ______.
• A) Camshaft
• B) Flywheel
• C) Crankshaft
• D) Transmission input shaft
,,answer,,,: C. Crankshaft
Rationale: The harmonic balancer (vibration damper) is mounted on the
front of the crankshaft to absorb torsional vibrations.
2. Most small gas engines use a _________ ignition system.
• A) Magneto
• B) Battery coil
• C) Electronic control unit (ECU)
• D) Distributorless
,,answer,,,: A. Magneto
Rationale: Small engines (lawnmowers, chainsaws) often use a magneto
system because it does not require a battery.
3. Icing occurs most often ______.
• A) On hot dry days
• B) On cool damp days
, • C) In freezing rain
• D) During high humidity only
,,answer,,,: B. On cool damp days
*Rationale: Carburetor icing is most common in cool, damp weather
(typically 30-50°F) where humidity freezes due to the temperature drop from
fuel vaporization.*
4. The function of the float in a carburetor is to ______.
• A) Meter air flow
• B) Close the needle valve
• C) Regulate idle speed
• D) Control the choke
,,answer,,,: B. Close the needle valve
Rationale: The float rises with the fuel level to close the needle valve,
stopping fuel flow once the bowl is full.
5. To improve stability when cornering manufacturers added a device to cars
called ______.
• A) Anti-roll bar
• B) Stabilizer bar
• C) Sway bar
• D) All of the above
,,answer,,,: D. All of the above
Rationale: "Stabilizer bar," "Sway bar," and "Anti-roll bar" all refer to the
same component designed to reduce body roll.
6. Adjustment of the rods on a car will affect ______.
• A) Camber
• B) Caster
• C) Toe-in
, • D) Steering angle
,,answer,,,: C. Toe-in
Rationale: Adjusting the tie rods changes the toe alignment (the difference in
distance between the front and rear of the front tires).
7. A restriction in the exhaust system is indicated on a vacuum gauge by a
______.
• A) Sudden drop to zero
• B) Gradual decrease in reading
• C) Fluctuating needle
• D) Steady increase in vacuum
,,answer,,,: B. Gradual decrease in reading
Rationale: As RPM increases, a restricted exhaust (clogged catalytic
converter) causes backpressure, which makes the vacuum reading slowly
drop rather than hold steady.
8. Disc brakes on a car have a distinct advantage over conventional drum
brakes in that they ______.
• A) Are cheaper to manufacture
• B) Fade less when hot
• C) Require less maintenance
• D) Last longer
,,answer,,,: B. Fade less when hot
Rationale: Disc brakes dissipate heat faster because the rotor is open to the
air, unlike drum brakes which trap heat inside the drum.
9. In a diesel engine, the fuel is ignited by the ______.
• A) Spark plug arc
• B) Glow plug
• C) Heat of compression
, • D) External flame
,,answer,,,: C. Heat of compression
Rationale: Diesel engines use compression ignition; air is compressed until
it reaches a high temperature, then fuel is injected and ignites
spontaneously.
10. Engine timing is generally set by using a ______.
• A) Dwell meter
• B) Multimeter
• C) Strobe light
• D) Vacuum gauge
,,answer,,,: C. Strobe light
Rationale: A timing light (strobe light) flashes when the #1 spark plug fires,
allowing the technician to view the timing marks on the harmonic balancer.
11. If an engine is operating for long periods of time at part throttle opening
the ______.
• A) Pistons will overheat
• B) Spark plugs will become covered with carbon
• C) Valves will stick
• D) Fuel mixture will lean out
,,answer,,,: B. Spark plugs will become covered with carbon
Rationale: Prolonged low-speed or idling operation leads to incomplete
combustion, resulting in carbon fouling of the spark plugs.
12. Leaking intake valve guides will cause ______.
• A) Low compression
• B) Excessive oil consumption
• C) Coolant in the oil
