Rocker Arms & Components

Rocker components transfer camshaft motion to the valves. Designs vary by engine: rocker shaft assemblies with adjusting screws on many diesel and truck engines, roller rocker arms (finger followers) with hydraulic lash adjusters on overhead-cam engines, and pushrod systems on some commercial engines.

Wear comes from poor lubrication, sludge and extended oil change intervals, causing noise, loss of valve lift and incorrect clearances. Specify by engine code, intake or exhaust position, and whether rocker arms include rollers or adjusters. Hydraulic lash adjusters should be stored upright and kept sealed to avoid air ingress and contamination. See cylinder head components.