Effects of Engine Oil Supply on Rocker Arm and Ball Wear

Wear of engine components is affected by lubricant quality and flow and by the metallurgy of the rubbing parts. Recent studies have shown that after starting an engine at sub-zero temperatures, more than 6 min elapsed before oil reached all of the rocker arm assemblies of a V-8 engine. Since this could have an adverse effect on rocker arm and ball wear, the effects of intermittent and zero oil flow on rocker arm and ball wear were investigated. The metallurgy of the rocker balls influenced ball wear greatly. Even when run for 9 h with no oil flowing to them, sintered iron alloy balls had very little scuffing or wear, whereas sintered iron balls were heavily scuffed and worn. In addition, the impregnant used in sintered iron alloy balls influenced wear. With one type of organophosphorus impregnant, excessive scuffing and wear was observed, whereas with another organophosphorus and an oleic acid impregnant, little wear and no scuffing were found.