HIGHROAD & BY-ROAD

Waikato Times, Volume 107, Issue 17964, 8 March 1930, Page 11 (Supplement)

HIGHROAD & BY-ROAD

■ •> *mi DIAGNOSING TROUBLE.

Coincidences are sometimes frightfully misleading, which is another way of saying that things are not always what they seem when it comes to diagnosing road trouble. As an example, consider the experiences of the motorist who stalled his motor in shifting gears. However, before he could put his foot on the starter pedal a big cloud of 'blue-grey smoke arose from tlic region of the switch-panel on the instrument board, accompanied by an ominous splitting produced by a heavy short circuit. Frantic operation of the various switches did no good and for an instant it looked as though the car might catch fire, but a moment later a hot sizzling wire dropped to the floor and the danger was passed, the spluttering stopped and the smoko melted away. The insulation of this wire was charred, but examination showed that none of the other connections had been harmed. First thought was that this trouble was the cause of the stalled engine and much annoyance ensued until it was suggested that the burning wire was merely coincidental with the stalling, which was accidental. Thereupon, the ignition switch was turned on, the starter pedal pressed 'and away the motor whirred, as good as ever, yet the charred wire was still lying on the floor where it had dropped. Later inspection showed that the electric system was in good working order, with the exception of one headlight.

SPARK PLUG EFFICIENCY.

A spark that will jump across a gap in the open air may not have the power to jump the same gap under compression. Consequently, the spark must be especially strong and capable of jumping a gap under compression as well as in the open air. That is a point sometimes overlooked, and it often is thought that just because the spark plug is operating corrocrly when tested in the atmosphere, it will do so when screwed into the cylinder. 1L is a mistake easy to make and one well worth considering when conducting a test. Try, therefore, to adjust the gap to achieve a compromising distance. If the points are too close together it may be 'mpossiblc to run slowly, for the actual area of flame will be too small to fire toe charge at the instant the power impulse is needed. On the 'Other hand, if the gap is too wide it may cause misfiring on a high compression engine because the compression is greatly increased every time the throttle is suddenly opened for quick acceleration. Therefore, try to keep the gap at a happy medium—-about .025 of an inch, or equal to the thickness of a visiting card. This gap will take care of practically any condition of ignition and show the best results.

GET EXPERT ADVICE. One of the most frequent causes of purchasers buying, their experience in second-hand cars in the bitter school of disappointment, is the reluctance of the average man to admit that he doesn’t know anything about the inner mechanism of a car. If your knowledge is limited to ability to drive it from one place to another, then, before purchasing a second-hand car, admit the fact and seek the advice 'Of someone who does know, and when you feel that, the advice is impartial relief and act upon it. No second-hand car can be purchased without first having subjected it to a road test. Not just a run up and down a level street, but a real spin on an average give-and-take road, if you are satisfied with the car’s performance on the road and wish to go further in the matter, the next step should be a thorough examination.

WHEN THE “VAC” TANK J!SS. The most common cause of the failure of the vacuum tank is from leakage of air which prevents the intake manifold connection doing its work of creating a vacuum to induce the flow of petrol from the main tank to the vacuum tank. Sometimes, some foreign substance may cause a stoppage of the petrol feed from the “vac.” tank to the carburettor. This may easily be tested by unscrewing the drain plug underneath the tank, when, if the tank Is apparently full, it may safely be assumed that the fault does not lie within the mechanism of the tank, but most probably is due to a dogged outlet pipe. If the tank floods when the engine is running, It is a pretty sure indication that either the float or the vaouum tank have beoome punctured or that the valve mechanism has jammed. It Is not uncommon for the motorist to find that the liquid rubber cement In his tube-patching outfit has deteriorated with age when he finds it necessary to repair a puncture far from the world of garages 'and service stations. One motorist in such a predicament made a satisfactory repair in the following manner: a rough sort of vulcanising being resorted to. ’lhe punctured portion of the tube was cleaned and roughened with a scraper as usual, and then a few drops of petrol were poured on It. This was fruited with a match and allowed to bum until consumed. The cold patch was then applied immediately and pressed firmly in place. This completed the repair, which proved to be quite satisfactory for several hundred miles.