Feasibility studies have shown that radioactive test techniques can be used to investigate engine-oil-fuel compatibility problems. A chrome faced piston ring set and a cast iron cylinder liner were irradiated and installed in a compression ignition, multifuel engine. The engine was operated under conditions which tend to produce scuffing in the ring belt. Since iron and chromium emit gamma rays at widely different energy levels, it was possible to measure simultaneously the wear in each component by monitoring radioactivity of the lubricating oil.
By this technique the surface condition of the piston rings and of the cylinder liner at any given period was accurately described by the radiation measuring instruments. Changes in wear rates as rings became seated, or with changes in lubricant were clearly shown. The start of scuffing (marked by a radical increase in wear rate- 2000% on liner) was also clearly defined. It was possible to tell which component scuffed first, the time interval before the other component started scuffing, and the effect of engine operating conditions on the severity of scuffing.
This feasibility study showed that radioactive techniques can make a worthwhile contribution to engine-oil-fuel compatibility testing. The capability of this technique to develop data unobtainable by any other method far outweighs the added cost and complexity of its use.