CYLINDER WEAR

Stratford Evening Post, Volume II, Issue 355, 12 September 1933, Page 3

CYLINDER WEAR

o Results of Experiments THEORIES UPSET All theories of the cause of cylinder wear have been upset by the recent publication by the Institute of Automobile Engineers in England of the results of exhaustive research, states a motoring journal. The results are so startling and contradictory to accepted ideas that many exi perienced motorists will hesitate to take advantage of them. Tn the past the aluminium alloy piston was thought to be largely the cause on the ground that its comparatively soft composition permitted abrasive particles to become embedded in the bearing surfaces, where they scored the cylinder walls. Then the more exacting working conditions of the modern high speed engine, excessive ring pressure, ring hammer, and faulty lubrication were blamed in turn, but all attempts at improvement failed. The report places the blame in an entirely new quarter. It states that the result of many carefully conducted experiments has proved that the wear is caused by the corrosive action of the moisture resulting from combustion in the cylinder head. This moisture was minimised, if not eliminated, once the temperature of the cylinder walls exceeded 125 deg. centigrade. Stopping and starting tests showed that, provided that the engine was warmed up snlllicently fast, delayed lubrication and strangling of the carburetter did nut accelj erato wear. This, of course, means that the habit of letting an engine “tick over” slowly when starting from cold is more likely to cause harm than good. Another unexpected result is that dilution of the lubrication oil with kerosene up to 90 per cent, did not produce accelerated wear except when the oil was contaminated with abrasive matter. It did, however, cause trouble with other moving parts of the engine. It was also discovered that with cylinder wall temperatures of 125 deg. to 265 deg. ceni tigrade, under steady running conditions, a deficiency of oil was unlikely to bo a factor of practical importance in cylinder wear. As the | temperature diminished, however, even with good lubrication, the wear rapidly increased. This research was carried out under the most exacting conditions, and should prove of material assistance in overcoming the difficulty and preventing the need for re-boring. The solution of excessive cylinder and piston ring wear will, it is expected, be found in the use of metals having a very high resistance to corrosion, such as an iron containing 14 per cent of nickel, 6 per cent, of copper and 2 to 4 per cent, of chromium. According to these results users of cars themselves can help to reduce the rate of wear by “warming up” their engines as quickly as possible, by keeping the radiator covered, and by shielding part of it. Radiator shutters or a thermostat device arc, of course, also useful. The oil in the crank case should be maintained at a high level, and to help to prevent corrosion before the engine become warm some upper cylinder lubricant should be used, or 1 to 2 ounces of oil should be added to each gallon of petrol. The upper-cylinder lubricant is preferable, however.