What indicates that a bore is past its wear limit?

The measurement of a bore exceeding the engine cylinder specification is critical because it directly reflects the wear and degradation of the cylinder over time. Engine cylinders are designed with precise specifications that dictate their maximum allowable dimensions. When the bore measurement surpasses these specifications, it indicates that the cylinder has worn out beyond the point of acceptable limits. This excessive wear can lead to insufficient sealing and a loss of engine efficiency, increased oil consumption, or even mechanical failure.

In contrast, simply matching engine cylinder specifications does not provide any indication of wear—it shows that the cylinder is still within acceptable limits. A shiny appearance may signify normal wear or polishing of the cylinder walls but does not necessarily correlate to them being over the wear limit; polishing can occur from proper operation. Additionally, producing less noise typically indicates smooth running and effective operation, not related to the bore's wear findings. Thus, exceeding the specified bore measurement is the definitive sign of wear that exceeds acceptable limits.