WHEN A BIG-END “GOES”

Dominion, Volume 21, Issue 17, 14 October 1927, Page 9

WHEN A BIG-END “GOES”

tVAALUX* X * IM A.AWXUW A run-out . big-end generally is the cause of a great deal of noise, often so bad that pedestrians will hear a car on which such a bearing has given out approaching some distance away. The noise is generally hard, sharp, and loud,, except in less severe cases, where it is first noticed as a dull thudding. The sound caused by a run-out big-end bearing varies also according to how much the engine is pulling, and is less conspicuous if the engine be pulling hard, as when ascending a steep hill slowly. A main bearing that is giving trouble generally causes a dull thudding sound, accompanied by a very considerable vibration. Sometimes, especially in six-cylinder engines, a misfiring sparking plug will cause vibration, and a dull thudding sound similar to that caused by slightly-worn big-end or main bearing, instead of making itself more evident. Therefore, the owner-driver who suspects a worn-out bearing as the result of a persistent thudding, accompanied by a lack of power, would do well first of all to examine and clean all the sparking plugs, noting then whether there is any improvement. A similar effect may be produced if, after an overhaul, the firing order is upset, and is set, say, so as to fire in the order 1,2, 4,3, instead of 1,3, 4,2, or vice versa. However, such a mistake is invariably denoted by obvious misfiring, and the remedy simply consists of changing over the high-tension wires to the two middle cylinders, which will not have been firing on the compression stroke; numbers 1 and 4 only working.