AERA Engine Rebuilding Techniques & Procedures 3 — Questions and Answers
Question 1: What is the recommended honing angle (crosshatch pattern) for most cylinder bores to achieve proper ring seating?
- 15–20 degrees
- 45–60 degrees included angle (Correct answer)
- 75–90 degrees included angle
- Over 90 degrees included angle
Correct answer: 45–60 degrees included angle
A crosshatch angle of 45–60 degrees (included) provides the correct oil retention and ring-seating characteristics for most applications.
Question 2: What does 'deck height' refer to in engine rebuilding?
- Distance from crank centerline to block deck surface (Correct answer)
- Height of the cylinder head above the block
- Piston protrusion above the block deck at TDC
- Thickness of the head gasket
Correct answer: Distance from crank centerline to block deck surface
Deck height is the distance from the crankshaft centerline to the top (deck) surface of the block, a critical dimension for compression ratio and gasket selection.
Question 3: Which condition requires replacement rather than reconditioning of a crankshaft?
- Journal surface finish rougher than spec
- Out-of-round journals within 0.001 inch
- Cracks detected by magnetic particle inspection (Correct answer)
- Journals undersize by 0.010 inch
Correct answer: Cracks detected by magnetic particle inspection
Cracks discovered by magnetic particle or dye penetrant inspection are cause for crankshaft rejection; cracked cranks cannot be safely reconditioned.
Question 4: When installing camshaft bearings, what alignment is critical?
- Bearing parting lines must face up
- Oil hole in bearing must align with oil passage in block (Correct answer)
- Bearing must protrude 0.005 inch above bore
- Bearing width must exceed journal width
Correct answer: Oil hole in bearing must align with oil passage in block
The oil feed hole in each camshaft bearing must align precisely with the corresponding oil passage in the block to ensure proper lubrication.
Question 5: What is 'bearing crush' and why is it important?
- The oil film thickness under load
- The amount bearing shell extends beyond the housing bore to create interference fit (Correct answer)
- The difference between rod bore and crankpin diameter
- The preload on the bearing cap bolts
Correct answer: The amount bearing shell extends beyond the housing bore to create interference fit
Bearing crush is the slight protrusion of each bearing half beyond the housing parting face; when the cap is torqued, this interference locks the bearing in place and improves heat transfer.
Question 6: Which tool is used to measure piston ring end gap?
- Ring groove micrometer
- Feeler gauge with ring positioned squarely in the bore (Correct answer)
- Outside micrometer
- Dial bore gauge
Correct answer: Feeler gauge with ring positioned squarely in the bore
Ring end gap is measured by placing the ring squarely in the cylinder bore at the wear limit and measuring the gap with a feeler gauge.
Question 7: During engine assembly, why must all oil passages be verified clear before installation?
- To reduce pumping losses
- To prevent metal debris from starving bearings of oil and causing immediate failure (Correct answer)
- To increase oil pressure readings
- To comply with EPA standards
Correct answer: To prevent metal debris from starving bearings of oil and causing immediate failure
Any blockage in an oil passage will starve downstream bearings of lubrication, leading to seizure within seconds of startup.
AERA Engine Rebuilding Techniques & Procedures 3
What is the recommended honing angle (crosshatch pattern) for most cylinder bores to achieve proper ring seating?