Score lines are defects that are linear and found on parts that move long distances in the same direction, such as pistons.

Score lines are defects that are linear and found on parts that move long distances in the same direction, such as pistons.

• A. Not stated
• B. True
• C. False
• D. Only on rotating parts

Answer: (B)

Score lines are linear wear marks formed when surfaces slide against each other in a consistent direction. In engines, reciprocating parts like pistons move a long distance in the same general path during each stroke, so any rubbing or abrasive contact can leave these straight grooves along that direction. They indicate surface damage from rubbing, usually due to insufficient lubrication, debris, or improper clearances that allow metal-to-metal contact as the parts move. That’s why the statement is true: score lines are a linear defect associated with parts that travel long distances in one direction, with pistons being a classic example. The idea that this would only happen on rotating parts isn’t accurate, since reciprocating components can also develop score marks. Not stated isn’t correct because the description accurately describes score lines. False isn’t correct because the defect is indeed linear and linked to directional movement.

Score lines are linear wear marks formed when surfaces slide against each other in a consistent direction. In engines, reciprocating parts like pistons move a long distance in the same general path during each stroke, so any rubbing or abrasive contact can leave these straight grooves along that direction. They indicate surface damage from rubbing, usually due to insufficient lubrication, debris, or improper clearances that allow metal-to-metal contact as the parts move.

That’s why the statement is true: score lines are a linear defect associated with parts that travel long distances in one direction, with pistons being a classic example. The idea that this would only happen on rotating parts isn’t accurate, since reciprocating components can also develop score marks. Not stated isn’t correct because the description accurately describes score lines. False isn’t correct because the defect is indeed linear and linked to directional movement.