ASE Practice Test (A1: Engine Repair) 1 — Questions and Answers

Question 1: The cylinder head's surface has just been machined. What will have to do to the valve train?

Grinding valve stems (Correct answer)
Lengthening the push rods
Shim the head
Increasing valve spring tension

Correct answer: Grinding valve stems

Machining the cylinder head surface removes material, effectively lowering the head and bringing the valves closer to the camshaft/rocker arms. This reduction in height can cause the valve stems to protrude too far, leading to incorrect valve lash or even coil bind. Grinding the valve stems shortens them, restoring proper valve train geometry and ensuring correct valve operation after the head has been resurfaced.

Question 2: A cylinder leakage test is used to diagnose an engine miss. Technician X says that any cylinder with over 20 percent leakage has excessive leakage. Technician Y says that air leaking from the tailpipe indicates a cracked cylinder head. Who is right?

Both X and Y
Neither X nor Y
Y only
X only (Correct answer)

Correct answer: X only

Technician X is correct because a leakage rate exceeding 20% is generally considered excessive and indicates a significant problem within that cylinder, such as worn rings or valve issues. Technician Y is incorrect; air leaking from the tailpipe during a cylinder leakage test typically indicates a leaking exhaust valve, not necessarily a cracked cylinder head. A cracked cylinder head would more likely show leakage into the cooling system or an adjacent cylinder.

Question 3: The engine is making a rattling noise, according to a client. It's coming from the drive belt/serpentine belt system, according to Technician A. The following step is to:

Replace the drive belt
Inspect the pulleys for signs of excess play or bearing noise (Correct answer)
Replace the drive belt tensioner
Inspect the drive belt for signs of wear

Correct answer: Inspect the pulleys for signs of excess play or bearing noise

If a rattling noise is identified as coming from the drive belt system, the next logical step after initial diagnosis is to pinpoint the exact source. Pulleys with excessive play or worn bearings are common culprits for rattling or squealing noises in the serpentine belt system. Inspecting them directly helps identify the failing component before simply replacing parts.

Question 4: Which of the following causes a flapping noise near the front of the engine?

Drive belt too tight
Timing belt tension too loose (Correct answer)
Drive belt too loose
Timing belt tension too tight

Correct answer: Timing belt tension too loose

A loose timing belt can cause a flapping or slapping noise because it has too much slack and can whip around as the engine operates. This excessive movement can lead to the belt hitting components or simply creating noise due to its uncontrolled motion. Proper tension is critical for the timing belt's quiet and efficient operation.

Question 5: When the engine is cold, an engine noise sounds like a knock on the side of the engine. When the engine achieves operational temperature, the noise goes gone or is lessened. Which of the following is the MOST LIKELY reason for the problem?

Piston slap (Correct answer)
Cam bearing
Wrist pin
Main bearing

Correct answer: Piston slap

Piston slap occurs when there's excessive clearance between the piston skirt and the cylinder wall, especially when the engine is cold. As the engine warms up, the pistons expand more than the cylinder walls, reducing this clearance and causing the knocking noise to diminish or disappear. This characteristic behavior is a classic symptom of piston slap.

Question 6: An idle vacuum test is carried out by a technician. The 2001 Sedan's test results show a pressure of 11 in. Hg. What should the technician check next?

Check for proper timing (Correct answer)
Look for weak valve springs
Check for exhaust restriction
Look for a sticking valve

Correct answer: Check for proper timing

An idle vacuum reading of 11 in. Hg is significantly lower than the normal range (typically 17-21 in. Hg at sea level), indicating a potential engine problem. Low vacuum can be caused by several issues, but incorrect ignition timing (retarded timing) is a common cause that directly affects engine efficiency and vacuum production. Checking timing is a logical and relatively easy diagnostic step to perform next.

Question 7: While cleaning the pleated paper-type air filter element, the air gun should be held:

Directly against the inside of the air filter element.
Away from the outside of the air filter element.
Away from the inside of the air filter element. (Correct answer)
Directly against the outside of the air filter element.

Correct answer: Away from the inside of the air filter element.

When cleaning a paper air filter with compressed air, the air should be blown from the *inside out* to push trapped dirt particles away from the clean side. Holding the air gun *away* from the inside allows the air to expand and gently dislodge particles without damaging the delicate filter media. Blowing from the outside in or holding the gun too close can embed dirt deeper or tear the filter.

Question 8: When doing an engine compression test, you must disable the fuel injection, ignition systems and all of the following reasons, except:

Prevents damage to the ignition system during the test
Prevents fuel injection into the cylinders
Prevents shop engine fire
Prevents inaccurate readings (Correct answer)

Correct answer: Prevents inaccurate readings

Disabling the fuel injection and ignition systems during a compression test is primarily done to prevent fuel from entering the cylinders (which could wash down cylinder walls or create a fire hazard) and to prevent the ignition system from firing (which could damage components or cause a shock). It does not directly prevent inaccurate readings; rather, it ensures safety and prevents secondary issues that could complicate the test. Accurate readings are achieved by following the correct test procedure, not by disabling these systems for accuracy itself.

Question 9: A power balance test is being performed on an engine. Technician X says to note the engine RPM before and during the test for each cylinder. Technician Y says to record the RPM drop for each cylinder. Who is right?

Neither X and Y
Both X and Y (Correct answer)
X only
Y only

Correct answer: Both X and Y

Both technicians are correct. A power balance test involves individually disabling cylinders and observing the resulting RPM drop. Technician X's approach of noting RPM before and during the test is necessary to calculate the RPM drop. Technician Y's instruction to record the RPM drop is the direct measurement used to compare the power contribution of each cylinder. Both steps are integral to accurately performing and interpreting a power balance test.

Question 10: An air leak within the cylinder is what you're searching for when performing an engine compression test. This test will reveal air leaks in all of the following, with the exception of which?

Cylinder head gasket
PCV valve (Correct answer)
Intake or exhaust valve
Piston rings

Correct answer: PCV valve

An engine compression test measures the ability of a cylinder to hold pressure, thereby revealing leaks past the piston rings, intake/exhaust valves, or the cylinder head gasket. The PCV (Positive Crankcase Ventilation) valve is part of the crankcase ventilation system and is external to the combustion chamber's sealing integrity during a compression test. While a faulty PCV valve can cause vacuum leaks, it does not directly affect the compression within the cylinder itself.

Question 11: What might happen if new rings are installed without removing the ring ridge?

The connecting rod bearings may be damaged.
The piston ring or top compression ring may crack or break (Correct answer)
The piston skirt may be damaged
The piston pin may be broken.

Correct answer: The piston ring or top compression ring may crack or break

A ring ridge is a wear step at the top of the cylinder bore, above the travel of the top piston ring. If new rings are installed without removing this ridge, the top compression ring will hit it during upward piston travel. This impact can cause the new, sharp-edged ring to crack, break, or become severely damaged, leading to immediate compression loss and engine failure.

Question 12: Technician X says the closed coil end of a valve spring should go against the cylinder head. Technician Y says all valve springs use shims to control free spring height. Who is right?

Y only
X only (Correct answer)
Neither X nor Y
Both X and Y

Correct answer: X only

Technician X is correct. Valve springs often have a 'closed' or tighter wound coil end, which is designed to be placed against the cylinder head or spring seat. This helps reduce spring resonance and provides a more stable base. Technician Y is incorrect; not all valve springs use shims. Shims are used when necessary to adjust spring installed height and tension to specification, but they are not universally required for every valve spring application.

Question 13: Technician X says old antifreeze may cause corrosion build-up in the cooling system. Technician Y says some original equipment manufacturers (OEM) recommend that the coolant be changed at specified intervals. Who is right?

Both X and Y (Correct answer)
X only
Neither X nor Y
Y only

Correct answer: Both X and Y

Both technicians are correct. Over time, the corrosion inhibitors in antifreeze deplete, allowing rust and other deposits to form, which can damage cooling system components. Therefore, OEMs specify regular coolant change intervals to maintain proper corrosion protection and ensure optimal cooling system performance. Neglecting these intervals can lead to significant engine damage.

Question 14: A customer complains about white smoke coming from the exhaust system. You should start by checking which system for low fluid levels?

Brake Master Cylinder
Transmission
Cooling System (Correct answer)
Engine Oil

Correct answer: Cooling System

White smoke from the exhaust typically indicates that coolant is entering the combustion chambers and being burned. This is often a symptom of a leaking head gasket or a cracked cylinder head. Therefore, checking the cooling system for low fluid levels is the most logical first step to confirm if coolant is being consumed, which would support this diagnosis.

Question 15: Technician X says a special puller and installer tool is required to remove and install the vibration damper. Technician Y says that if the intertia ring on the vibration damper is loose, the damper must be replaced. Who is right?

Both X and Y (Correct answer)
Y only
Neither X nor Y
X only

Correct answer: Both X and Y

Both technicians are correct. Vibration dampers (harmonic balancers) are often press-fit onto the crankshaft, requiring specialized pullers and installers to prevent damage during removal and installation. Furthermore, the inertia ring, which is crucial for dampening engine vibrations, is bonded to the hub. If this bond fails and the inertia ring becomes loose, the damper's effectiveness is compromised, and it must be replaced to prevent excessive engine vibration and potential damage.

Question 16: When adjusting valve lash on engines with overhead camshaft cylinder heads, all of the following statements are correct, EXCEPT:

The follower or rocker must be on the base circle of the camshaft when measuring.
Clearance is measured between the camshaft and follower or rocker on most engines.
The engine must be cold for all engine manufacturers (Correct answer)
Shims may be used to make adjustments.

Correct answer: The engine must be cold for all engine manufacturers

While many manufacturers specify valve lash adjustments on a cold engine, it is not universally true for *all* engine manufacturers. Some engines, particularly older designs or specific performance applications, may require hot adjustments to account for thermal expansion. Therefore, stating that the engine *must* be cold for *all* manufacturers is an incorrect generalization.

Question 17: In the illustration, what engine seal is shown?

Throttle valve
Valve (Correct answer)
Rear main
Camshaft plug

Correct answer: Valve

Assuming the illustration shows a valve stem seal, this component is a small rubber or synthetic seal that fits around the valve stem. Its purpose is to prevent engine oil from leaking down the valve guide into the combustion chamber, which helps control oil consumption and prevents carbon buildup on the valves. This is a critical seal for the engine's proper operation.

Question 18: Which components inside the valve train are most likely to create a significant amount of excess engine noise?

Worn rod bearing
Worn connecting rods
Worn or dirty rocker arms (Correct answer)
Worn crankshaft seal

Correct answer: Worn or dirty rocker arms

Worn or dirty rocker arms, especially their pivots or contact surfaces with the valve stem or pushrod, can lead to excessive valve lash. This increased clearance causes a distinct ticking or tapping noise as the components impact each other with greater force. Other valve train components can also cause noise, but worn rocker arms are a very common source of noticeable engine noise.

Question 19: When pressing the wrist pin into the piston and connecting rods, which of the following steps is the technician LEAST likely to perform?

Heat the small end of the rod
Make sure that position marks on the piston and connecting rod are oriented properly
Heat the wrist pin (Correct answer)
Align the bores in the piston and connecting rod

Correct answer: Heat the wrist pin

For press-fit wrist pins, it's common practice to heat the small end of the connecting rod. This causes the rod's bore to expand, allowing the wrist pin to be pressed in more easily and securely. Heating the wrist pin itself would cause it to expand, making it *harder* to press into the rod, which is the opposite of the desired effect. Proper orientation and alignment are also critical steps.

Question 20: Below are the following ways the piston is attached to the rod, EXCEPT:

Woodruff key (Correct answer)
Press fit to piston
Press fit to rod
Free floating

Correct answer: Woodruff key

Pistons are typically attached to connecting rods via a wrist pin (also called a gudgeon pin) using one of three common methods: press-fit to the piston, press-fit to the rod, or free-floating (secured by circlips). A Woodruff key is a crescent-shaped key used to secure components like gears or pulleys to a shaft, preventing rotational movement, and is not used in piston-to-rod attachment.

Question 21: A technician is testing the ECT (Electronic Controlled Throttle) circuit with a stored DTC P1121 on a laptop computer with manufacturer software (Electric Throttle Control Actuator). Which of the following customer complaints might be caused by a defective ECT return spring malfunction?

Low power (Correct answer)
Rough idle
Detonation
High idle

Correct answer: Low power

A defective ECT return spring, indicated by DTC P1121, means the throttle plate may not fully open when commanded. This restriction in airflow to the engine prevents it from achieving its full power potential. Consequently, the engine will produce less power than expected, leading to a customer complaint of low power.

Question 22: A customer complains that their engine isn't producing enough power. It was an sudden change. The technician notices that the engine coolant is low and that there is white smoke coming from the exhaust during the check. Which of the following best describes the situation?

Faulty main bearing insert
Faulty valve guide
Cracked cylinder wall (Correct answer)
Worn piston ring

Correct answer: Cracked cylinder wall

White smoke from the exhaust, combined with low engine coolant and a sudden loss of power, is a classic symptom of coolant entering the combustion chamber. A cracked cylinder wall allows coolant to leak directly into the cylinder, where it burns and produces white smoke. This internal leak also compromises cylinder compression and combustion, leading to a noticeable and sudden reduction in engine power.

Question 23: Technician X says before you remove an engine assembly, the battery must be disconnected. Technician Y says to assist in reassembly, you should take a photograph of the engine compartment before you remove any components or connectors. Who is right?

X only
Y only
Neither X nor Y
Both X and Y (Correct answer)

Correct answer: Both X and Y

Technician X is correct because disconnecting the battery is a fundamental safety precaution before working on major engine components, preventing electrical shorts or accidental starting. Technician Y is also correct, as photographing the engine compartment provides an invaluable visual record for proper reassembly, ensuring all components and connectors are returned to their correct locations. Both practices are essential for safe and efficient repair.

Question 24: The noise fades while a cylinder is being evaluated during the cylinder balancing test, and the engine makes a knocking sound that changes with RPM. Which of the following could be the root of the problem?

Main bearing
Rod bearing (Correct answer)
Burnt Valve
Piston slap

Correct answer: Rod bearing

A knocking sound that changes with RPM and fades when a specific cylinder is deactivated during a balancing test strongly points to a connecting rod bearing issue. When the load on a cylinder is removed, the stress on its rod bearing decreases, causing the characteristic knock to diminish. This diagnostic method helps isolate the problem to a specific rod bearing.

Question 25: Which of the following is the best diagnostic approach for identifying if a fuel injector is defective without having the manufacturer electrical specifications?

Determine if all injectors have the same electrical resistance (Correct answer)
Test for fuel pressure at the fuel rail
Remove them and clean them
Look to see if they squirt fuel

Correct answer: Determine if all injectors have the same electrical resistance

When diagnosing a potentially defective fuel injector without specific manufacturer electrical data, comparing the electrical resistance (ohms) of all injectors is the most effective approach. All injectors of the same type should exhibit very similar resistance values. A significant deviation in resistance for one injector indicates an internal electrical fault, such as an open or short circuit, confirming it as defective.

Question 26: Which of the following processes is NOT necessary when refilling a cooling system?

Bleeding the air out of the system
Check the radiator cap for proper fit
Mixing the proper ratio of water to coolant
Mixing tap water and distilled water (Correct answer)

Correct answer: Mixing tap water and distilled water

Mixing tap water and distilled water is not a necessary process when refilling a cooling system; in fact, it's counterproductive. Tap water contains minerals and impurities that can lead to scale buildup, corrosion, and reduced cooling efficiency over time. Only distilled water should be mixed with coolant, or a pre-mixed coolant solution should be used, to maintain system integrity.

Question 27: Technician X says the voltage required maintaining spark is referred to as the spark line and the duration of the spark line is based on total primary circuit resistance and coil voltage available. Technician Y says problems with the burning (called fuel propagation) will show up within the spark line. Who is right?

Neither X nor Y
Both X and Y
Y only (Correct answer)
X only

Correct answer: Y only

Technician Y is correct because the spark line on an oscilloscope provides crucial information about the combustion process, including how well the fuel is burning (fuel propagation). Issues like lean mixtures or misfires will directly impact the appearance and duration of the spark line. Technician X's definition of the spark line and its duration factors is inaccurate.

Question 28: You run a cylinder compression test and get a zero compression rating along with a lot of engine blowby. Which of the following is indicated by this?

A hole in a piston (Correct answer)
Severely burned exhaust valve
Cracked cylinder head
Leaking head gasket

Correct answer: A hole in a piston

Zero compression in a cylinder, coupled with significant engine blowby (combustion gases escaping into the crankcase), is a definitive indicator of a major mechanical failure. A hole in a piston would directly cause a complete loss of compression and allow a large volume of combustion gases to bypass the piston, resulting in excessive blowby. Other issues like a burnt valve or cracked head would typically show some, albeit low, compression.

Question 29: Which of the following showed that the cooling system is contaminated?

ATF (automatic transmission fluid) in the coolant (Correct answer)
Pink colored coolant
Orange and slimy feeling coolant
Bubbles when the radiator cap is removed

Correct answer: ATF (automatic transmission fluid) in the coolant

The presence of Automatic Transmission Fluid (ATF) in the coolant is a clear sign of cooling system contamination. This typically indicates an internal leak in the transmission cooler, which is often integrated into the radiator. The cooler allows ATF to mix with the engine coolant, signifying a breach in the system.

Question 30: What should you do first when attempting to diagnose coolant consumption?

Check engine oil condition and level
Visually look for external cooling system leaks
Either A or B
Perform a cooling system pressure test (Correct answer)

Correct answer: Perform a cooling system pressure test

When diagnosing coolant consumption, the most effective first step is to perform a cooling system pressure test. This test pressurizes the entire system, making it easier to identify both external leaks that might not be visible under normal conditions and internal leaks, such as a faulty head gasket or a cracked block, by observing a pressure drop.

ASE Practice Test (A1: Engine Repair) 1

The cylinder head's surface has just been machined.
What will have to do to the valve train?