AERA Component Inspection & Quality Control 5 — Questions and Answers
Question 1: What is the purpose of checking valve margin (head thickness) during a valve inspection?
- To determine correct spring installed height
- To ensure the valve can withstand heat without burning or mushrooming (Correct answer)
- To set valve lash correctly
- To confirm the valve stem length is correct
Correct answer: To ensure the valve can withstand heat without burning or mushrooming
Insufficient valve margin (thin head edge) means the valve cannot absorb and dissipate combustion heat adequately, leading to burning and failure.
Question 2: Which condition would cause a connecting rod to fail a 'stretch' measurement?
- Oil hole misalignment
- The rod has been subjected to overload, causing permanent elongation (Correct answer)
- Incorrect bronze bushing material
- Excessive big-end bore diameter
Correct answer: The rod has been subjected to overload, causing permanent elongation
A rod that has been overstressed will be permanently stretched beyond its original center-to-center length, making it unfit for reuse.
Question 3: Before assembling bearings, the oil clearance is measured by which method that uses a compressible plastic strip?
- Bore gauge and micrometer method
- Plastigage method (Correct answer)
- Lead wire method
- Feeler gauge method
Correct answer: Plastigage method
Plastigage is a crushable plastic strip placed between the bearing and journal; the width of the crushed strip corresponds to the oil clearance on the included scale.
Question 4: When a valve spring is tested for squareness, the maximum allowable lean from perpendicular is typically:
- 1/32 in (0.8 mm)
- 1/16 in (1.6 mm) (Correct answer)
- 3/32 in (2.4 mm)
- 1/8 in (3.2 mm)
Correct answer: 1/16 in (1.6 mm)
Most specifications allow a maximum of 1/16 in (1.6 mm) lean from perpendicular; a spring leaning more than this produces uneven side loads on the valve stem.
Question 5: A fluorescent dye penetrant inspection requires what final step before the part is examined under UV light?
- Application of developer powder or spray (Correct answer)
- Heating the part to 200°F
- Rinsing with hot water only
- Applying a second coat of penetrant
Correct answer: Application of developer powder or spray
Developer draws the penetrant out of defects and provides a contrasting background, making cracks visible as bright fluorescent indications under UV (black) light.
Question 6: When inspecting a used timing chain, the maximum allowable stretch before replacement is typically measured as:
- Any elongation beyond original length
- Elongation that causes timing to be retarded more than 3–5 degrees (Correct answer)
- More than 1/2 in of slack in the chain run
- Chain pitch increase of more than 0.010 in per link
Correct answer: Elongation that causes timing to be retarded more than 3–5 degrees
If chain stretch causes camshaft timing to retard more than 3–5 degrees from specification, valve timing and engine performance are compromised enough to require replacement.
Question 7: Which of the following is the FIRST step when establishing a quality control inspection sequence for rebuilt engines?
- Torquing all fasteners to spec
- Verifying all component part numbers match the build sheet (Correct answer)
- Performing a hot leak-down test
- Checking final assembled weight
Correct answer: Verifying all component part numbers match the build sheet
Confirming every component matches the build sheet before assembly prevents incorrect parts from being installed, which is a foundational QC step.
AERA Component Inspection & Quality Control 5
What is the purpose of checking valve margin (head thickness) during a valve inspection?