COOLING THE ENGINE

Rotorua Morning Post, Volume 3, Issue 700, 28 November 1933, Page 2

COOLING THE ENGINE

POINTS ABQUT YOUR AIR AND OTHER COOLING * . SYiSTEM. Mjany cars which have completed several thousand miles will be apfc to overheat if certain; matters bave been neglected. In the first place, the radiator cap should be removed at regular interr vals in order to miake sure that the water level is near to the top. If this simple precaution be negelected the level will graduaJly drop and, particularly in clars witli thermo-syphoh circulation, a critical stage is so'on reached. This, according to an article in a recent issue of The Motor, occurs. When the top of the pipe leaddng from th'e engine to the radiators hecomes unoovered; circulation will carry on for a longer period with'ouit sbowing signs of distress, but, here again, regular lattention is highjy.desirable. When Boiling Occurs. Should shortage of water or some other cause result in boiling when the car is on the road, the symptoms are usually loss of power accompanied hy pinking, but stCam may not be visihle so long as th'e car is running. This is hecause /the vapour plassesdown an overflow pipe and is carried away beneath the vehicle without hedng seen. As soon as the car is brought to a standstill, the steam rises around the radiator and one can hear sizzling land bubbling noises

which sh'ow that boiling is in progress. IGreat care should he taken when removing the radiator cap in such oircumstances, hecause a considerr able : pressure of scteam may have been cre'ated which will hlow the cap into the air, with a gush of boiling Water, so .soon as it is unscrewed. Th'e hest plan is therefore to wait for ten minutes or so before making an investigati'on. It is also very important to give the engine quite a long time in which to cool down before adding fresh cold water. The fluid may have boiled away to helow the level of the cylinder heads, in which case all these matai parts miay well h'ave be^come nearly red hot before the car was brought to a standstill. Cold water impinging upon such surfaces is very likely to produce cracks. Fan Belt Adjustment. Turning to the precautions which should he taken to avoid boiling trour bles, the first point to consider is usually the tension of the belt imployed to drive the fan. In many rnodem cars th'e fan spindle projects into the front of ,the water jacket and carries an impeller, or bladed wheel, which assists water circulation. Should the belt become slack it will slip in the pulley, so reducirig the speed of the fan. Less air will then pass through th'e radiator and, if an impeller he also iniconporafeed, tihe rate of water flow will simultaneously deerelase. As a rule, some quite simple means is provided for the adjustment of the fan belt, either hy rai'sing the fan unit as a whole or by closing together •the flanges of the fan pulley. Exfreme tightness is not desirable hecause it dncreases the wear and tear on the belt and hearings, to no useful purpose. Wlater leaks are not liable to occur in a fairly new car, although some trouble with hose connectdons may follow when an engine has been decarhonated. The only other eommon source of leakage is at the gland which is provided to sea! the orifiee through' which -the spindle emerges from the pump or impeller housmg* Tightness Not Desirable. In the course of time the packing ibecomes worn and. it can then he

forced into closer contact with the ispindle iby screwing the gland nut through' part of a turn. Here aigadn, undue tightness is not desirable, as the compressed packing may damage , the spih#e. «In! course of time ithe packing loses elasticity, becomdng dry and hard, so that no amount of adjustment will prevent leakage of water. In such circumstances, of course, it is neces'sary to have the packing renewed. It remains to point out that the heat to h.e dds$ipate,d hy the co.oling ( system will increase if the engine is j not working efficiently. An und.uly ' weak mixture, for example, hy burn- j ing slowly through'out the expansion • strofce, will give up more heat to the | bore than will a quick-burning ch'arge of the correct petrol-air ration. Simi•larly, a retarded spark may cause trouble.