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How to warm up a cold engine?

Cold starting is the procedure that really ruins our engines. A lot of engines would last much longer, if they weren't forced to press cold, stiff and non-lubricating oil through the oil-pump, until it, more or less, does it's job. All this time, the engine suffers from mixed- or even dry-friction. Our engines, also and particularly, the petrol driven ones, would last much longer, if they were to run continuously.

Indeed, the veteran cars with a seasonal number plate are better off. Through the winter months they stand protected in the garage, probably with fresh oil and corrosion prevention sprayed into the spark plug holes. These expensively restored or even rebuilt babies are far too valuable to be taken out at icy temperatures, just for the sake of driving a few kilometers. If however, they have to be driven, it is advisable to learn how an engine is properly warmed up.

What can be seen in the above picture, is an absolute jewel of an engine. It was created by the famous Italian tuner, Carlo Abarth, who after the Second World War, spurred not only the little Fiats on to breathtaking performance. He himself, had a very unique way of warming up the engine. He would drain off the oil, then warm it up in a sort of saucepan. Some may have shaken their heads at this rather wierd method of race- preparation, but basically, this was the right thing to do.

Not the temperature of the cooling liquid, but that of the oil is vital. Unfortunately, in modern cars nowadays, the oil-temperature-gauge has all but dissapeared. Indeed, if one has been added, it is more than likely wrongly installed, e.g., with the sensor replacing the drain plug, you can read why here. The higher an engine is stressed by the displacement power, the more important it is to allow the engine oil to reach approx. 80°C before high performance is demanded. A great deal of damage to the engine could be prevented by not overstraining the cold engine.

The additional danger with engines which suffer from cold-running damage, is that one does not notice it immediately. In this respect by the way, the petrol engine is traditionally more at risk than the Diesel, because in this operational range, it runs with a richer mixture, from which a portion is mixed in with the oil and this reduces the effectivity. The intact Diesel engine never runs as rich, indeed, there are recently oil additives being used which serve the regeneration through supplementary injection.

So, what it's all about is damage to the engine that the user hardly notices. Earlier, the Diesel engines, e.g., used to hammer loudly when they were still cold. This however, has been, as a concession to the respective neighbours, largely eliminated. It became even worse. Because these engines are trimmed for less and less fuel consumption, they also have less heat-loss, which delays their warming up process.

We are simply becoming more comfort-conscious. Nowadays, hardly anyone can even imagine doing without the interior heating for a while, for the sake of the engine. Indeed it does only make a certain degree of sense, because with air-conducted heating in a small circuit, the heat exchanger is provided with warmth right from the word go. At least it doesn't cool down that quickly, if it is not fed with cold air to the interior.

In days gone by, with the air-cooled engines, the warmth was provided free of charge, because fresh air was always sucked in from outside to cool the engines. However, even at the time of, e.g., the VW-Beetles, a bellows-thermostat filled with alcohol regulated the heating, indeed, whether the air was guided to the interior or to the outside, didn't make any difference to the engine. Apart from that, they were later converted to 'fresh-air'-heating by heating the air separately through the exhaust warmth. Either way, the result was pretty poor.

Nowadays, instead of the Abarth-method, one uses stationary heating, available as an optional extra. Of course, the engine only profits from this method, if the heating also heats the coolant. In North America and in Scandinavia, some cars are fitted with simple electric block-heaters, which can be connected to the available mains outlets in all public car-parks. In Germany e.g., the vehicles of the fire brigade are fitted with such systems.

Thus, we normal car drivers simply can't avoid warming up the engine by driving, even if we combine the trips in winter. Thereby basically, high RPM proves to be the certain death of the engine. It's not how the gas pedal is handled, but the gear lever, the higher gears are to be reached as quickly as possible. Whether you put your foot down or not, has almost no meaning as far as the temperature increase of the engine is concerned.

We say 'almost', because in summer you may notice that the temperature gauge (coolant) rises a little when you drive uphill in top-gear. In most cars the cooling pump is coupled directly to the crankshaft, which at high RPM, provides more heat circulation and thus, good cooling.

This is why the newer systems are better, instead of having one thermostat to regulate the coolant circulation at low temperatures, they have either electrically driven pumps or they can be switched off completely. Indeed, these are still quite rare. The way to do it is, don't let the engine idle for longer than necessary, drive off straight away and change to the next higher gear as soon as possible, above all, avoid high RPM. This also saves fuel in this operational range where the engine has a tendency to excessive fuel consumption anyway.

One solution to the problem could be the developing hybrid-area, however, only in the area where the batteries can be charged from the mains (plug-in). Perhaps only three kilometers are needed for your errands (or maybe later more). You may also have the time and the possibility to recharge on your way. For longer stretches you can first run the batteries down (e.g., through stop-and-go) and then let the engine recharge them again, which will certainly warm it up faster.

VW also has solutions for the current cars. The warmer side of all transverse mounted engines would be moved to the rear. The intercooler is placed directly before the cylinder inlets, and to achieve a better heat control, is fitted with its own, electrically driven, cooling circuit. This way the heat distribution could be better regulated. In addition, the exhaust manifold part of the cylinder head, and thus the heat exchange with the cooling system, should be intensified.

If you don't have a plug-in hybrid or the newest VW-technology, give a thought to Carlo Abarth. Remember, not the coolant-, but the oil temperature is what it's all about and generally, this takes very much longer. Also, if you have a manual gearbox, then change gears a little slower than usual, since also here, the oil must first be warmed up through the movement of the gear-wheels. 01/12