MOTORDOM

Greymouth Evening Star, 16 April 1937, Page 9

MOTORDOM

NEWS OF THE ROAD

(By

“Gearbox”)

TRACING TROUBLE. THE MISFIRING ENGINE. Ten years ago expert knowledge of tbo causes of misfiring was part of tno equipment of every motorist worthy oi the name, and as the trouble was failcommon, the average driver had plenty of opportunity to practice his skill in tracing and rectifying the fault. On the whole, trouble of this sort today is rare. Nevertheless, every man and woman who drives a car is almost certain to meet with it at some time or another. If, when the car is stationary a “miss” is suspected and the engine is running so quietly that it is difficult to decide with definiteness from beside the bonnet, the best thing to do is to walk to the back of the car and listen to the exhaust. When the engine is firing with regularity, th eexhaust will play what amounts to a quiet, steady tune, but if one cylinder is not firing there will be a curious and regular break in the noise, so that the steady purr becomes a beat. When driving the car, it is more difficult to decide whether the engine is misfiring, so well balanced are modern engines. But by listening carefully, and separating the engine sound from the other noises a car makes when it is travelling fairly fast, the irregular firing will often be manifested by an unaccustomed drone, accompanied perhaps by a noticeable, though small, increase in vibration felt through the throttle pedal, which is extraordinarily sensitive, to variations in engine behaviour.

In older, noisier and rougher engines, it is impossible to overlook misfiring, as one cylinder out of action will upset the whole power unit, and often there is a definite and regular break in the running of the unit.

To return to modern cars, there are other symptoms which indicate trouble. "One is the rapidity of the rate of acceleration. For example, a motorist having become familiar with car, may know that his car will accelerate to 30 m.p.h. within a certain distance in second gear. If acceleration is palpably slow, and is not caused by gradual, general deterioration in engine tune, a misfiring sparking plug may reasonably be suspected, especially if this slow acceleration is accompanied by the altered engine note. But perhaps the best way of deciding whether misfiring is present is to make the car accelerate in top gear from a very low speed, say 10 m.p.h. The unusual load placed on the engine will have the effect of exaggerating the irregularity, and engine operation will be definitely “rough.”

FINDING ERRING PLUG. Once the conclusion is reached that one spark plug is not functioning properly, the next step is to discover which plug is at fault. Open the bonnet and look along the plug wires to see if one wire has become detached from its terminal. If it has, the plug to which that wire belongs is almost certain to have become covered with oil, and should be removed and thoroughly cleaned or replaced with a new plug.

However, the chances are that all the plug wires will be in place. That will mean that one plug is faulty. To determine which one, the neon tube type of tester is frequently useful. This tester is not a costly item of equipment, and is worth having in the tool kit, especially if a long trip is being undertaken. The tester is applied to each plug terminal in turn while the engine is running, and if the plug is sparking at the points a spark will also occur behind the little window in the side of the device. When a plug is tested and no spark occurs, then the faulty one has been found, and it can be replaced immediately. There are some types of plugs which, for some reason or other, do not give good results with the neon tester. The old screwdriver test will then have to be made. Choose a screwdriver, the steel blade of which does not also form part of the handle, otherwise a severe electric shock will be received. In testing the plugs with this first apply the metal blade to some metal part of the engine, such as the edge of the cylinder head or the exhaust branch, and then apply the tip of the blade to the terminal of the plug. This short circuits the plug out of action, and if the engine slows immediately that particular plug is in good order. But if no difference is made in the engine speed, then the plug has not been 'sparking at the points, and it obviously is the faulty one. It is possible, of course, that the misfiring may not be caused by a faulty plug. Apart from other little derangements in the ignition system which may be responsible, more or less similar irregularity in running may finally be traced to loss of compression in one cylinder, perhaps caused by piston rings sticking in their grooves, I but more likely by a burned valve or a tappet “riding” on the valve stem, so that the valve cannot close completely.

If the valves are suspected, the tappets should be tested first when the engine is hot, making sure that each cam is clear of its tappet before coming to the conclusion that one tappet is tight against the valve stem. With the cams clear there should be a perceptible clearance between each tappet and valve stern, and if in one case there is not. then it is fairly certain that the trouble has been found, and slacking off Ihe tappet to provide the requisite clearance often will effect a cure. It should be remembered, however, that if the tappet has been “riding” for any length of time, it. is possible that the edge of the valve has become burnt.

through its exposure to the hot exhaust gases. In that case tiie damage has been done, and the only thing to do is to remove the head and regrind or replace the valve. Similarly, removal of the head and examination of the valve; heads and pistons is the course which must be followed if all other means to cure irregular running fail.

THE GARAGE. PLANNING HINTS. Many new motorists imagine all that is. needed for a garage is some form of erection which will just bouse the car. They estimate the dimensions according to the overall size of their present car and think that because the car is sft. Gin. in width, the garage need be little more. This is entirely wrong. It is essential to allow considerable additional overall width, sufficient at least for the door on one side of 'the car to be swung open fully, when driven close to the. other wall. A door is anything from 2ft. Gin. to 3ft. in width—possibly more on a close-coupled saloon with a single door on each side.

If ground space permits, it is best not to think in the terms of your present car, but rather the one.which you may be acquiring in due course. Reckon on having a big one (say 6ft. in width) and using this as a basis, plan a garage which is at least Bft. Gin. across and 18ft. long—better still, go even to 20ft. or more to give plenty of room at the forward end for the election of a bench. Naturally, the bigger the garage be the better for those concerned when working therein at any time. . If it has to be built behind the house, slightly overlapping, see to it that the garage is not put too close, as this will make it difficult to manoeuvre a car in and out through the restricted area between the house and the side fence. Put in 14ft. or so from the house; such spacing will give room for a wash down.

GOOD LIGHT NEEDED. Plenty of head room should, of course, be provided. The space above the rafters, if an inverted V-roof is employed, can be put to very good service for storage purposes. Remember that a garage is so often used for housing equipment for which loom cannot be found elsewhere. Make sure that there is good light; a window at the forward end and a window in each side wall is to be recommended. For working after dark have an electric light point laid on, together with a wall plug, which will enable-) you to use an inspection lamp on the end of a length of flex. A lamp of this type is, incidentally, an important part of the garage equipment, as it enables the light to. be thrown directly on the work in hand. Secuie enc which has a fairly stout handle and a wire cage over the bulb. A power point should be fitted as well so that a heater can be employed, and it will enable one to make use also of a vacuum cleaner for freshening up the inside of the car, particularly upholstery of the moquette type. An electric soldering iron is another item ot equipment which comes to mind, demanding a power point. Any spare tools should be mounted on a board and held by spring clips, Odd nuts, bolts and small incidentals can be stored in racks all marked ac-< cording to contents, whilst . cleaning materials should bo kept in a cupItems of garage equipment which come to mind as being useful tor all general service include a long-reach, jack on a pair of trolley wheels; hose with adjustable jet and nozzle; foot pump or a small mechanical compressor; the requisite supply of lubricant for treatment of the chassis bearings; a spray for the springs, a particularly strong wrench; a vice; a hand drill; a selection of files and a hack saw; a hand grinder and, if elaborate repair work is to be undertaken, such tools as taps and dies, a lathe, bearing scrapers, etc.

CAR RADIO IN U.S.A.

E.S.T. in “The Motors” (London) states that in America motorists who equip their cars with radio enteitain net only themselves but the man in the street—to say nothing about the traffic “cop.” “I happened to be in Harlem, the coloured quarter of New York, on the night of the Louis-Sclnneling light, he says. “On each side of Lexington Avenue, the main thoroughfare, I saw nothing but parked cars with a knot of persons around listening to the radio commentary on the fight. The drivers obligingly turned up the volume so that as many persons as possible could hear. It was almost practicable to hear the whole commentary by walking up and down the street, taking up the description from car to car. “Harlem is a heavily-policed district—there are two or more officers to every block. Naturally the police were not going to forgo heai ing the broadcast, and usually the officer seized the best position—head inside the open window of the car, and the rest of his anatomy outside. At one time I saw a vista of nearly a dozen cars, each with the. rear portion of a policeman protruding, while excited piccaninnies scampered about the running boards. “It wa£ the same during the political conventions. Frequently in the big cities 1 saw a parked car with the radio turned on at a generous blast for the benefit of pedestrians who were j interested in the political antics at Cleveland or elsewhere. During a I traffic block a score or more loudI speakers would be broadcasting the I same announcement, and it was obviI ous that the point-duty policeman on ! occasions were lending an interested ear - "Scenes like these are to be observled in American towns whenever there lis an important sports or , political bioadcast on a wide ‘hook-up.’ motor-driven bicycle.

Far many years there has appeared to bo a big potential field for a. small, i Oieicnt power unit that could be built into :• pedal bicycle, thereby providing the. rider with the means of combining th'? utility and pleasure of cycling, yet lidding him of much labour- Such a unit is now in production in England. 1! is a !i<S c.c. two-stroke engine, which js built into an ordinary bicycle in an ingenious manner, the frame of the machine being specially strengthened. This motor-assisted bicycle, known the “Cyc-auto,’’ is stated to be easily. handled with simple controls. There. are. no gears to change, no clutch to operate, and no ignition control to juggle with. while the . carburettor is entirely automatic in action. - The tiny engine is set in front

of tile crank-bracket, to which it is &-'! fixed, while a. half-gallon petrol tank is, I laced behind the saddle of the nia(him . Tiammiis.’son is by chain. T’ho machine is ridden primarily as a Irec-j wheel pedal cycle would be. To start i the fi'. ine, the. rider pedals oil lrom| . i-m-istill. Until the little enginci gets into its stride the pedals are used; to help it. along, but once the unit hast wanned to its work the rider can cease pedalling, and simply coast along. The maximum speed is about 30 miles pet hottr under favourable conditions. A gallon of petrol is sufficient to run machine, about 110 miles. I lie lidci, with light pedalling, can climb long stiff gradients with ease. The outfit weighs only 851 b., and fully equipped sells in England for £l7/17/-.