Some Observations of the Effect of Lubricating Oil Properties on Combustion Generated Engine Vibrations 690451
Engine noise of the type related to a bending vibration of the crankshaft was investigated in a V-8 spark ignition engine. Abnormally high rates of combustion pressure rise were induced by introduction of carbon particles into the intake manifold, thereby providing multiple ignition sources in one cylinder.
It was determined that wide variations in oil temperature and viscosity had no influence on the occurrence of vibration or the apparent magnitude of the accompanying noise. However, lubricating oil bulk temperature and viscosity did each have some measurable effect on the magnitude of the crankshaft deflection.
Upon completion of the investigation, examination of the bearing disclosed damage, caused by the protracted inducement of bending vibration, apparently while operating with oil at very low viscosity.