The Lubrication of Engine Valve Trains Equipped with Ceramicized Followers

The valve train wear characteristics of motored 2.2 l and 2.3 l engines were examined using ceramic and conventional metal cam followers. Under regular wear conditions with fully formulated motor oils, minimal wear was observed on the metal cam lobes running with either the ceramicized or metal followers. Running under chemically accelerated wear conditions with low quality oil, however, cam lobe wear with ceramicized followers was observed to be significantly less than that with metal followers. The difference in wear was diminished when testing high quality oils under chemically accelerated conditions. Typical testing revealed that the metal follower pads quickly developed considerable wear in a characteristic pattern, while the ceramic followers exhibited only slight polishing. Scanning electron photographs revealed details of the used ceramic surfaces, and that wear took place by polishing and by intergranular fracture with subsequent material removal.