AERA Component Inspection & Quality Control 3 — Questions and Answers
Question 1: A camshaft lobe lift measurement that is below specification by more than 0.005 in indicates:
- Excessive end play
- Lobe wear requiring camshaft replacement (Correct answer)
- Incorrect base circle runout
- Normal break-in wear
Correct answer: Lobe wear requiring camshaft replacement
Significant lobe lift loss means the lobe profile has worn down, reducing valve lift and engine performance, requiring camshaft replacement.
Question 2: To check valve stem-to-guide clearance, a technician inserts the valve and rocks it sideways while measuring movement with a:
- Telescoping gauge
- Dial indicator at the valve head (Correct answer)
- Feeler gauge between stem and guide
- Small-hole gauge
Correct answer: Dial indicator at the valve head
A dial indicator positioned at the valve head rim measures total side-to-side movement, which is then compared to the stem-to-guide clearance specification.
Question 3: What does a blued (heat-discolored) zone on a crankshaft journal indicate?
- Proper hardness from induction hardening
- Overheating from oil starvation or bearing failure (Correct answer)
- Successful nitride case treatment
- Normal oxidation during engine break-in
Correct answer: Overheating from oil starvation or bearing failure
Blue discoloration on a journal indicates it reached temperatures exceeding 400°F, typically caused by oil starvation or a spun bearing, compromising the journal's hardness.
Question 4: When inspecting pistons, which area is most critical to measure for diameter to determine piston-to-bore clearance?
- Top of the piston crown
- Below the oil ring groove at 90° to the pin bore (Correct answer)
- At the pin bore centerline
- At the top ring groove land
Correct answer: Below the oil ring groove at 90° to the pin bore
Piston diameter is measured at the thrust face (90° to pin bore) near the skirt bottom where the piston is largest and controls bore clearance.
Question 5: Dye penetrant inspection (Zyglo) is used on aluminum and non-ferrous parts because:
- It is faster than magnetic particle testing
- Non-ferrous metals cannot be magnetized for mag-flux testing (Correct answer)
- It detects subsurface cracks better than magnetic methods
- It requires no cleaning of the part after testing
Correct answer: Non-ferrous metals cannot be magnetized for mag-flux testing
Magnetic particle inspection requires ferrous metals; dye penetrant works on any material and is therefore the NDT method of choice for aluminum castings.
Question 6: When measuring piston ring gap, the ring must be squared in the bore using:
- A ring compressor tool
- The piston itself pushed inverted into the bore (Correct answer)
- A feeler gauge set flat in the bore
- A ring expander tool
Correct answer: The piston itself pushed inverted into the bore
Inverting the piston and pushing the ring down with it ensures the ring sits perpendicular (squared) to the bore walls for an accurate gap measurement.
Question 7: What is the correct procedure for checking camshaft bearing bore alignment in a block?
- Use a straight edge across the top of the bores
- Insert a long, straight mandrel through all bearing bores and check for binding or light gaps (Correct answer)
- Measure each bore individually with a bore gauge
- Check oil passage alignment with a probe
Correct answer: Insert a long, straight mandrel through all bearing bores and check for binding or light gaps
A precision mandrel passed through all camshaft bores simultaneously reveals misalignment if it binds or if light is visible between the mandrel and any bore.
AERA Component Inspection & Quality Control 3
A camshaft lobe lift measurement that is below specification by more than 0.005 in indicates: