THE CAR EOF A MOTOR CAR.

Taihape Daily Times, 14 October 1919, Page 5

THE CAR EOF A MOTOR CAR.

It is strange how often one hears, a motorist boast of the fact that his? car has run for two or even three years without being overhauled or tuned up.‘ Where this occurs, it is generally to be found that the owner is without that sensibility and sympathy which enables him t-0 realise when his power ‘plant begins to slowly, but surely, fall olf in vetfectiveness. The change is slow and gradual, no doubt, -but still it should be possible to locate it, and it is of great importance that it should be realised at once, for it inevitably denotes the need for attention. The most serious source of loss, as a. rule, is want of compression. This may arise from a variety of canes, such as the pitting of the valves, the fact t‘ha.t.. one -or other of the ‘valves fails to close absolutely, due to the end_of the tappet rod remaining in contact, the breakage or wear ‘of piston rings, or the shifting of same, so that the slots come adjacent to each other; a bad joint in th-e cylinder he.ad, allowing the escapelof compression; or wear in the cam surfaces (which is rare). Sometimes the trouble may be only in on-e cylinder, making it more difiicult to diagnose‘. If the trouble is serious one can test it by slowly turning the starting handle, but as a: rule, ‘at compression -gauge is necessary, and unless the owner ha.s some expert knowledge, it would be better for him to take the car to an expert. Another fruitful source of trouble is the deposit of carbon on the tops of the pistons and the walls of the combustion chamber, due, usually, -to excessive lubrication causing the oil to get past the piston rings, and in some: cases to faulty carburation. Such deposit, needlessto say, reduces the size -of the l combustion chamber, and also is likely to cause pre ignition. The Valve timing also may be faulty, needing the resetting of the tappets». The clearane-e should be only just. sufiicient to leave i the "smallest possible space betw"éen the top of the tappet an-d the {ralve stem—- , abeutl-64th of an ,in:cll_,,i,smani'ple. Igniy tion troubles, also, will cause a fallingR off in power. These may result from ordinary short circuits, or,may_be__due lto the ends of the plug electrodes be- ‘, iilg_.too far apar.t,gal_ld_, to en_sure_their I synchronisation, "gho"uld‘ be ch_ecke'd"at l regular intervals Wear ‘in the contact. l maker disc, or contact pointspvitill "also 5 cause trouble, and sonietim'es'the fibre ‘laisc is at fault, or thddistributor is dirty or worn. An occasional’ overl- : haul of a car is wise, and a payable out. i lay in the long run. ‘