At he Wheel

NZ Truth, Issue 1198, 15 November 1928, Page 20

At he Wheel

PISTON SLAPJS COMMON Often Mistaken For Valve Noise

gCORES of engines m what might be termed the middle age » period of their existence, that is, between 18 and 30 thousand j^ miles, suffer from piston slap, without their owners having any I idea that anything is the matter.

1 CLIGHT piston slap can very easily kJ be mistaken for valve clatter, but it has this important difference, whereas the noise of a valve is present under all conditions .of driving, piston slap is more audible when the engine is being hard driven, and frequently disappears when the car is pushing the engine. Piston slan also seems ' n accountably to disappear for short nerinrift ant\ *hnn „„(,„„. ; .•u. I waging * " without " ' It Is an annoying- phenomenon, but as Jong as the engine is treated care-' 1 ;- ■■■■ • •■: :. . ■ ■

fully and- not raced, the engine*can run and perform creditably without much danger. When, however, the noise becomes loud and bell-like, it is time to have repairs undertaken, Except where the cylinder has become scored, oversize pistons will usually cure the trouble, but as piston trouble is sometimes met with after a temporary shortage of oil, it sometimes happens that the cylinder wall itself nag l sU&htly damage*. In this case the cylinder will have to be scraped, and m bad cases rebored. - —v . ■- • •