HINTS FOR MOTORISTS

Bay of Plenty Times, Volume LVII, Issue 10146, 8 August 1929, Page 4

HINTS FOR MOTORISTS

NEW EQUIPMENT FOR T'HE SERVICE GARAGE.

Inability to determine, by exact methods of measurement, the horsepower actually delivered by the driving tyres of a car that is not performing properly, has always tended bo render cufficult the tracing and correction of defects in running. Moreover, the lack of practical means'for testing: engines under load, with the car at rest, has hitherto made it very difficult to locate abnormal engine noises, which could only bo heard with the car on the road, under conditions which made exact methods of diagnosis impossible of application. In technical schools and motor car factories, there have been in use electric and other types of dynamometers upon which a oar -could be run and given a “brake horsepower” test, but access to such apparatus has, generally speaking, ■ been out of the question. Recently, however, o iif keeping with the general 1 -trend in the motor ' car business to substitute exact testing and service methods for rule-ot-thumb and hit-or-miss procedures, there have been devised and placed upon the market, for installation in serlvice (stations, dynamometer testing stands, somewhat similar in arrangement to the brake testing installations now well known in the industry. A oar can be driven on to one of these dynamometer installations and run under varying loads, as if it were on the road, the power delivered by the wheels being absorbed by a hydarulic or .other form of brake, while tests are conveniently made upon the engine or other units to determine actually what is wrong. . „ . ~ While not as yet in sufficient y widespread use to be generally available, it is not unsafe to predict that, in the not distant future, they will be found in many of the first-class service stations. These devices are likely to become as useful as the various brake testing devices which service stations are now installing. A year or two ago “hit-or-miss methods of adjusting brakes were customary even in fairly well equipped garages. . The mechanic jacked up the car, screwed the lock-nut brake adjusting device until the brake band could be heard scraping against the hub, slacked it back until the scraping sound disappeared, and then repeated the process with the remaining throe wheels. If, after the four wheels had been attended to, the braking seemed to be better than it was before, the mechanic reported all correct. Usually the car was given a run on the road, but such runs told nothing except that stopping was reasonably satisfactory. There was then no means in general vise of deciding whether maximum efficiency had been achieved with the brakes. Some manufacturers, and some more than usually well-equipped service stations, could actually test the brakes by means of mechanical devices, but [these devices were too expensive to come within the scope of the small garage. . Lately a number of new devices have been introduced to make for better braking tests. A simple instrument is the decelerator. The inertia of a column of liquid is used to check the stopping distances of the car on a level road. A more elaborate device is the H.F. brake tester. This enables the power of the brakes at varying loads to be tested while the oar is in the garage. Briefly, the brake pedal is kept depressed at a standard pressure—usually one hundred pounds. The car is jacked up, supported in a level position by means of wooden blocks, and the jack removed. The wheel of which the brake is to be tested is put on to a framework containing two ridged rollers. Then a chain and sprockets are used to turn the wheel against the pressure of the brake, and the movement of the rollers beneath the wheel sets a gauge in motion. This indicates the braking force when the pedal is depressed at the standard pressure. * A device is incorporated that enables the weight carried by the wheel in question to be decided before the braking test is carried out. FAULTY CARBURETTER. A. L. D. writes: The carburetter of my car troubles me considerably by running over and I have to get out and turn the float round several times to stop it. What .is the remedy for this? Answer: Unless this flooding is caused by dirt which passes* through with the petrol and gets caught in the float valve seat, you will probably find it advisable to replace the float and valve parts, which you can have done at the service station of the manufacturer of your carburetter. Formerly it was customary to grind fin float valves, repair floats and straighten bent parts, but now it hardly pays to do this, considering the high price of labour and the ‘relatively low cost of replacement parts. Answer to R. H., whose oar is deficent in power: You had better have the compression of this engine tested with a compression-gauge and corrct any defects in gas-tight-ness of the cylinders which the test may disclose. Also make sure that the valve-setting and the ig-nition-setting are in accordance with directions. Have the carburetter inspected at the service station and have the spark coil tested. See if the car pushes over the garage floor harder than it ought, and, if so, locate the seat of friction and have it removed. EXCESSIVE OIL CONSUMPTION. A. L. D. writes: Last summer, my engine used too much oil, bub I wa« not surprised at this, as 1 knew that new piston-rings were needed. The new rings were put in and thert is now no oil pumping, but more oil than before is being used. Where, does it go ? Answer: There may be leakage directly from the crankcase. This often occurs when the engine is running, but ceases when it is shut down. Sometime when you drive into your garage, with the' engine warm, lay clean paper on the floor under the whole power-plant and let the engine run idle for a few minutes at, , say, 25 ra.p.h. speed. If you find oil droppings on the paper, it will indicate ia leak and give some idea a® to , it® location. If white smoke escapes from the muffler, considerable oil must be passing the pistons, although not enough to collect on the pistonheads* perhaps. Perhaps there may be considerable loss of oil in vapour form from the breather. Possibly a differeint brand or grade of oil would esifcape less rapidly.