What is the primary issue associated with excessive wear of valve guides after an engine overhaul?

Excessive wear of valve guides after an engine overhaul is primarily associated with inadequate lubrication. The valve guides are designed to allow the valve stems to slide smoothly while providing support and maintaining proper alignment. When lubrication is insufficient, friction increases between the valve stems and the guides, leading to accelerated wear.

This situation can arise from various factors, such as improper oil passage configurations, using the wrong type of oil, or failing to replace worn components during the overhaul process. Without adequate lubrication, the oil cannot effectively reduce friction and dissipate heat, causing premature wear of the guides, which can ultimately lead to performance issues and engine failure if not addressed.