CYLINDER WEAR

Rotorua Morning Post, Volume 2, Issue 237, 27 May 1932, Page 2

CYLINDER WEAR

LUBRICATIQN TROUBLE IN STARTINGr FROM COLD. LET ENGINE IDLE. That the upper portions ■ of the cylinders in motor engines should receive positive lubrication when the car is new, and also upon starting from cold, is continually pointed out by technicians and lubrication engineers. The piston rings are for providing and maintaining a seal b'etween the combustion chamher and the sump of the motor, and only a minute quantity of oil reaches them. On starting from cold, the oil in the sump is sluggish and somewhat gummy if ^ has been in use for a considerable period. Further, after the motor has been standing for a considerable period the oil on the cylinder walls drains back in to the sump, and there is no lubrication of the cylinder walls until the oil becomes warm, and consequently thinner and freer flowing. When starting from cold a considerable time elapses before the sluggish oil breaks up into a' mist, and until then lubrication of the cylinder walls does not take plaoe. Furthermore, in starting from cold a rich mixture is required and th,e choke control is generally pulled out to provide this. Only a portion is burned, and the rest condenses on the cold cylinder walls, breaking down what scanty lubrication may exist there. Heavy Wear. It will be seen, -then, that upon starting the cylinders are subject to very heavy wear, since there is a definite absence of lubrication for an appreciable period. It is a mistake to drive off without waiting for th'2 oil to reach the cylinder walls. It is a mistake, also, to raee the engine, and it is a further mistake to idle too slow. The engine should be run for five minutes or so, with the car still, at between 500 and 1000 revolutions a minute. To provide lubrication for the upper parts of the cylinder walls special oil is sometimes mixed with the benzine. An alternative method is to have an independent container from which the special upper cylinder lubricant is drawn by vacuum through a pipe leading to the induction pipe, whare is mixes with the petrol mixture and is carried into the combustion chamber. Very little oil will do. Several twostroke engines are solely lubricnted by oil mixed in the petrol. Some car manufacturers have provided positively for upper cylinder lubrication. It is at the start, however, that upper cylinder lubrication iS so necessary, and any method that will give it until the oil is flowing freely is advisable. The golden rule is never to drive straight off after starting up from cold, but always let the engine idle at the speed mentioned, and on a thin mixture (to prevent dilution) until it has warmed up. iviore cylinder wear takes place in the few minutes of starting than 011 many miles of heavy touring. This is why running a car about town is so expensive; the engine is never really in a fit contlition to do the work required of it. It usually takes about ten miles on the road to bring an engine into good working condition.