ASE Engine Repair and Performance 2 — Questions and Answers
Question 1: A cylinder leakage test shows 30% leakage on cylinder 3, and air can be heard escaping from the oil fill cap. What is the most likely cause?
- Burned exhaust valve
- Worn piston rings or cylinder wall (Correct answer)
- Leaking intake valve
- Blown head gasket between cylinders
Correct answer: Worn piston rings or cylinder wall
Air escaping through the crankcase (oil fill or PCV) indicates leakage past the piston rings.
Question 2: During a cylinder leakage test, air is heard escaping from the throttle body. Which component is most likely at fault?
- Exhaust valve
- Piston rings
- Intake valve (Correct answer)
- Head gasket
Correct answer: Intake valve
Air exiting through the intake system means the intake valve is not sealing.
Question 3: A wet compression test raises a low cylinder reading significantly. What does this indicate?
- Worn piston rings (Correct answer)
- Burned valve
- Cracked cylinder head
- Worn camshaft lobe
Correct answer: Worn piston rings
Oil temporarily seals worn rings, so compression rises when rings are the problem.
Question 4: An engine vacuum gauge reading fluctuates rhythmically between 14 and 18 in. Hg at idle. Technician A says this can indicate a burned or sticking valve. Technician B says it indicates a restricted exhaust. Who is correct?
- Technician B only
- Both A and B
- Neither A nor B
- Technician A only (Correct answer)
Correct answer: Technician A only
A regular rhythmic drop points to a valve problem, while exhaust restriction causes vacuum to slowly fall with rpm.
Question 5: Which tool is used to measure cylinder bore taper and out-of-round?
- Outside micrometer
- Dial bore gauge (Correct answer)
- Feeler gauge
- Plastigage
Correct answer: Dial bore gauge
A dial bore gauge measures bore diameter at multiple points to determine taper and out-of-round.
Question 6: An engine produces blue smoke on startup after sitting overnight, then the smoke clears. What is the most likely cause?
- Worn piston rings
- Leaking head gasket
- Worn valve guide seals (Correct answer)
- Rich fuel mixture
Correct answer: Worn valve guide seals
Oil seeps past worn valve stem seals while the engine sits and burns off at startup.
Question 7: What is the purpose of a torque-to-yield (TTY) cylinder head bolt?
- It is stretched into its elastic/plastic range for consistent clamping force (Correct answer)
- It can be reused indefinitely
- It requires no specific tightening sequence
- It is tightened only by torque, never by angle
Correct answer: It is stretched into its elastic/plastic range for consistent clamping force
TTY bolts are stretched past their yield point for precise clamp load and are normally replaced, not reused.
ASE Engine Repair and Performance 2
A cylinder leakage test shows 30% leakage on cylinder 3, and air can be heard escaping from the oil fill cap.
What is the most likely cause?