Problems with cooling systems are probably amongst the most frustrating a caravanner can encounter. Overheating should be avoided at all cost as it can lead to costly repairs. On vehicles fitted with an automatic transmission, overheating can increase the likelihood of the added complication of damaging the transmission. The main function of an automatic transmission fluid is to transmit power, just like axles or drive shafts. While doing this the oil generates heat.
Under normal operating conditions the temperature is kept at safe levels by circulating the oil through the radiator. However when additional loads are placed on the transmission, as in the case when towing, the additional heat build up cannot always be taken care of by the standard radiator To prevent any damage occurring from the extra heat an auxiliary transmission oil cooler must be fitted if the vehicle is used for towing. Not only does it keep the oil temperature down, it will also reduce the engine coolant temperature.
Unless otherwise recommended by the manufacturer, the transmission oil should bypass the normal radiator and only pass through the auxiliary oil cooler to achieve maximum cooling eHiciency. It is highly undesirable to use normal tap water in cooling systems. Sooner or later it will result in untimely and expensive breakdowns.
Modern cooling systems use a variety of coolants. Each type must be used as recommended to ensure many years of trouble free engine operation. Always follow manufacturers instructions in regard to topping up the system. Never add water to a system which contains some other substance unless as a last resort.
Something else that can contribute to overheating, and often not realised by motorists is the use of an air-conditioner. Whenever this is switched on the cooling system is subjected to additional heat. If the engine temperatures appear to be increasing more that "normal", when the airconditioner is used, always switch the unit off until such time as the temperature is down to a safe level.
Motorists faced with overheating problems should seek the advice of a radiator specialist. Generally these people are familiar with problems associated with particular vehicles and may recommend a large radiator, new thermostat, or just a clean out.