ASE Engine Repair 3 — Questions and Answers
Question 1: A cylinder leak-down test showing air escaping from the tailpipe points to a leaking:
- Exhaust valve (Correct answer)
- Intake valve
- Head gasket to coolant
- Piston ring
Correct answer: Exhaust valve
Air heard at the tailpipe indicates the exhaust valve is not sealing.
Question 2: Air bubbling in the radiator with the engine running often indicates:
- Combustion gases leaking past the head gasket (Correct answer)
- A stuck thermostat
- Low oil level
- A worn water pump belt
Correct answer: Combustion gases leaking past the head gasket
Combustion gases entering the cooling system bubble into the radiator, signaling head gasket failure.
Question 3: Valve stem seals primarily control:
- Oil entering the combustion chamber along the stem (Correct answer)
- Valve timing
- Combustion sealing at the seat
- Coolant flow
Correct answer: Oil entering the combustion chamber along the stem
Stem seals limit oil from running down the valve stem into the chamber.
Question 4: A dial indicator is used to measure crankshaft:
- End play (Correct answer)
- Oil clearance
- Bearing crush
- Ring gap
Correct answer: End play
A dial indicator measures crankshaft end play by reading axial movement.
Question 5: An overheating engine with a collapsed lower radiator hose at high RPM indicates a faulty:
- Hose or missing internal spring (Correct answer)
- Thermostat
- Head gasket
- Oil pump
Correct answer: Hose or missing internal spring
A collapsing lower hose lacks its anti-collapse spring or has softened, restricting flow.
Question 6: Ring end gap that is too small can cause:
- Ring ends butting and scoring the cylinder (Correct answer)
- Excessive oil consumption
- Low compression
- Blow-by past the rings
Correct answer: Ring ends butting and scoring the cylinder
Insufficient end gap lets the ends touch when hot, scuffing the bore.
Question 7: A camshaft lobe with measurable wear will most directly affect:
- Valve lift and engine performance (Correct answer)
- Oil pressure
- Coolant temperature
- Crankshaft balance
Correct answer: Valve lift and engine performance
A worn lobe reduces valve lift, hurting breathing and power.
ASE Engine Repair 3
A cylinder leak-down test showing air escaping from the tailpipe points to a leaking: