CARE OF THE CAR.

Auckland Star, Volume LXVII, Issue 206, 1 September 1936, Page 16

CARE OF THE CAR.

TRAVEL IN SUMMER. OVERHEATING PROBLEMS. ADJUSTMENTS TO BE MADE. Comfortable travel in hot weather is partly dependent upon the well-being of the chassis. No driver can feel happy if the water in the radiator boils upon the slightest provocation, or if an overheated exhaust pipe is cooking the floor beneath his feet, states "Tlie Motor," London. Simple adjustments often suffice to remedy overheating troubles. The fan belt, for example, may have been neglected right through the winter, with results that are only noticed on the first hot day. This belt also drives a water impeller in many cars, so that slip will affect both the flow of air and the circulation of water.

In modern cars tlie adjustment is usually easy to effect by an outward movement of one of the belt-driven components. Some of the older cars are ino'o troublesome, particularly in where the adjustment takes the forjn of a divided pulley. The idea is to move the pulley flanges closer to one another so that the belt rises in the "V" and becomes tighter. It is an exhausting process because the belt tends to jam and so resists adjustment.

Too tight a belt will cause undue wear in the bearings without any compensating virtue. Oil or grease on the belt will promote slip, no matter what adjustment is attempted. Fan bearings should be kept lubricated, and, for the pump, grease of good quality should be used which will resist boiling water.

Persistent trouble with boiling is often due to accumulations of fur and hard deposits in the radiator core, cylinder jackets, etc. Powerful flushing

may prove a sufficient remedy. Violent cleansing agents should not be used, because they may attack the soldered joints. Proprietary compounds are available which are safe and effective. By consistently using soft water for replenishment these troublesome deposits can be avoided. When Boiling Occurs. Boiling may occur for some time on the road, with the car moving fast, before the driver becomes aware of the trouble; the steam blows away unnoticed beneath the chassis. When this has been happening the radiator filler cap should be treated with caution after allowing time for the temperature and pressure to fall. Never pour cold water into an overheated engine; either obtain hot water or allow the systeta at least half an hour to cool down before replenishment.

Overheating, troubles are by no means always caused.by defective cooling. The ignition system, for example, may provide an inadequate advance for the spark, with the result that the mixture is burnt inefficiently. The quantity of heat passing/ to the cooling system will then be increased.

Similar results will follow if the carburetter is set to supply an unduly weak mixture or a very rich mixture. Instead of burning "with a bang," combustion proceeds slowly throughout the firing stroke, so that an abnormal number of heat units pass through the cylinder walls.

The amount of heat which disappears down the exhaust pipe is ' also affected by ignition "timing, mixture strength, valve timing and a general condition of the engine. An efficient power, unit, by making the best possible use of the fuel with which it is supplied, wastes a correspondingly small proportion of heat energy in the cooling system and the exhaust pipe. The choice of suitable sparking plugs is also important. Especially in low-built cars, the exhause pipe is often located in uncomfortable proximity to the front floorboards. In bad cases it'is .worth while to have a pipe specially frnade which will provide«. more clearance. Alternaare to wrap the pipe with asbestos fibre, or to arrange a scoop which will direct air between pipe and flooring when the car is on the move. Sometimes the rear edge of the bonnet can be wedged open, with advantage, to allow hot air to escape. Fuel Starvation. A most annoying trouble which- sometimes occurs in very hot weather is fuel starvation, indicated by a gradual i drying of the engine. The symptoms

are just the same'as would apply if the petrol pump had ceased to work. The cause, however, is the exaporation of petrol in the suction pipe, which produces a vapour lock and so prevents the pump from drawing more fuel from the tank. The only remedy is to wait for 15 minutes or more until the pipe cools down. 5 ' Then, if there is a hand primer on the pump, use this to bring the fuel from the tank instead of turning the engine for a long period with the starter motor. A vapour lock of this kind is usually formed at a point where the fuel pipe passes very close to the exhaust. If the trouble is persistent" it is worth while to have a new pipe-line fitted with a greater clearance.

Air-cooling is also very important around the sump. Excessive oil temperatures imply a risk of starved bearings and will usually be indicated by an abormally low reading oil the oil pressure gauge. The cleaning »f oil filters, regular replenishment and the .choice of a good and suitable lubricant are of especial importance under the more difficult conditions imposed by summer motoring.

Similar remarks apply to the gear box and back axle. Both these units contain oil, which is cooled by the movement of the car through the air, so that when atmospheric temperatures are high the oil tends to become over-heated. This reduces the "body" of the lubricant, lowering its efficiency, and enables it to escape more readily between shafts i ( uid their bearings.

The action of the brakes involves the dissipation of considerable quantities of heat to the atmosphere. The drums are not always cooled as efficiently as might be wished, particularly at the back, where they are often tucked away in the shelter of wide wings. Over-heating results in lost efficiency, because the drums expand (in some cases they also become distorted) and the pedal gets nearer and nearer to the floor boards. The Considerate Driver.

A considerate driver can make things easier for the engine and other chassis components by handling the gear box

and accelerator with discretion. Very high "revs" on the indirect gears result in excessive inertia loading on the bearings; on the other hand, labouring up a long hill at a low speed 011 top gear will aggravate cooling difficulties by cutting the flow of air. A reasonable use of the gear box should be attempted, with the aim of steering a middle course between these harmful extremes.

* There is a general impression that the inflation pressure of a tyre rises considerably on a hot day. it is true that a rise takes 'place, but, as a rule, this does not amount to more than two or three pounds per square inch. Tyres wear much more rapidly in the summer than in the winter, partly because they work at a higher tenipemture, but also because of the scrubbing and abrasive action of dry and gritty roads. Consequently, pressures should be watched, to ,givc the tyres every chance of standing up to the more sever conditions.