Piston slap is when one or more pistons are too small for the cylinder bore either through incorrect fitting during manufacture or due to excesive wear for whatever reason (oil level too low, wrong grade of oil, etc) and instead of travelling up and down the cylinder in a parallel manner, because the piston diameter is smaller than the cylinder then the piston tends to tilt on the downstroke and the noise is generated when the direction of piston travel changes to the upstroke and the piston is tilted in the opposite plane and the piston skirt "slaps" the cylinder wall.
This is why over a period of time that the excesive wear is generated at the bottom of the cylinder bore.
This used to be a common problem in high mileage cars in the 60' and 70's but is relatively rare in modern engines unless like probably in this case it is a manufacturing fault.
This is why over a period of time that the excesive wear is generated at the bottom of the cylinder bore.
This used to be a common problem in high mileage cars in the 60' and 70's but is relatively rare in modern engines unless like probably in this case it is a manufacturing fault.