CHAPTER XXIX

OVERHEATING THE ENGINE IN SUMMER

The automobile engine will heat up too quickly in hot weather, just as an individual will. No, we did not say overeat; though if you let the engine gorge itself too long on motor fodder, it will help to overheat as well as overeat. There are a variety of reasons for the overheating, which it is well for the novice to understand.

Those who have found it necessary during the winter to cover the radiator and take off the fan belt and do other things to keep the engine hot enough to run smoothly and with the proper vaporization and firing, may find in summer that they are having as much or more trouble in keeping the engine cool enough to run properly.

Generally speaking, the nearer to the boiling point we can run the engine without actually having the water boil and steam away, the more efficient it will be. Some engines, in fact, develop much less than the maximum horse-power because they are too well cooled, and yet we hear a great many complaints about the water boiling in the radiator and the engine overheating.

This would not occur if everything were working as the designer intended it should. During cold weather the man who drives with a retarded spark uses up more gasoline than necessary, but he is not bothered with overheating. When the mercury goes up he finds that his engine overheats and gives him trouble. He has not changed his manner of driving, and cannot understand why there should be trouble.

Driving the engine at high speed with the spark retarded is one very good way of overheating the engine. As a matter of fact, the battery ignition systems which are now coming more into use require considerable manipulation of the spark-control lever, and the tendency is, because the engine knocks at low speed, to leave the lever partly retarded, instead of advancing it, when a higher speed is reached.

With the magneto, it is the general practice to advance the lever to three-fourths or seven-eighths of the full range right after the engine is started and leave it there for practically all work, except very high speeds. This may be done largely with such a system, because the nature of the spark given by the magneto changes somewhat with the speed of the engine, and the equivalent of an automatic advance and retard of the spark occurs with the variation of speed of the motor. With the battery system, however, there is very little change in the nature of the spark effected by the engine speed.

A frequent cause of chronic overheating may be traced to sediment in the radiator which cuts off free radiation of the heat. This usually may be removed by the use of a saturated solution of washing soda and water. With the advent of summer each year it would be well to fill the cooling system with a solution of this sort and run the engine for several hours and then drain it off and refill the system with clean water. If in the system used a pump is employed, one should disconnect the upper hose from the radiator and run the engine to pump the solution out of the system. At the same time water from a hose or other source should be fed into the top of the radiator as fast as it is pumped out, and thus flush the entire system, before connecting up the hose again.

Where the thermo-syphon system is used, which does not employ a pump, this, of course, cannot be done, but one should remove both upper and lower hose connections after running the engine with the solution and wash it out with fresh water as well as possible. A hose inserted in the upper connection probably would force all the solution out with any collection of sediment, and the same process with the radiator ought to clean it out.

Fan belts are more likely to get out of order in hot weather than in cold weather; perhaps this is because the engine throws oil or grease more readily when it is warm. Belts should have grease enough to keep them soft and pliable, of course, but too much causes slipping. They should be wiped free of all oil occasionally. There is always a belt adjustment and this should be tightened so that there is sufficient tension to drive the fan at all engine speeds.

Some engines have the spokes of the fly-wheel shaped to form a fan, and where this is the case the oil pan and hood should be kept tight so that air will be drawn through the radiator rather than through other openings. If the radiator is not kept free from oil the outside passages will very quickly collect dust, which will prevent a free flow of air and cut off radiating surface, which also occurs when the front of the radiator is smeared too thickly with paint.

Pumps do wear out, but this is one of the last places to look for trouble. The action of the pump may be determined usually by removing the radiator filler cap when the engine is running and noting whether the water is circulating, but if a baffle plate is placed in the filler opening, it cannot be seen, and a test may be made in the same manner in which the cleaning solution is washed out, namely, by removing the top hose from the radiator and running the engine, while supplying water through the filler opening.

With the thermo-syphon system there is very little pressure generated and a slight obstruction will stop the flow of water. Therefore it is more necessary to keep the system free from sediment and to see that the gaskets at the joints are made with circular openings of the right sizes so as not to obstruct the flow of water. Likewise water must be kept above the top hose of the radiator in order to have any circulation in this type of cooling system.

Another cause of overheating, which it has been found very difficult to locate, comes from carelessness in stretching the hose over the pipe. In doing this sometimes the inner lining of the hose is loosened and folds back, covering the opening of the pipe, so that water does not flow freely. It looks all right from the outside, but an examination of the inside will show that it is almost entirely clogged at the end. Also, the lining of the hose will often loosen up and pieces will lodge where they cut off the circulation.

Keep the engine free from carbon and keep the valve push rods adjusted close, have the mixture as lean as possible and be sure the exhaust from the muffler is free. Taking care of these things and seeing that the other things mentioned are all right, will prevent most of the overheating which troubles the novice, if, indeed, not all of it.

They are things which should not be trusted entirely to chauffeur or garage man, but the owner should learn how to take care of them himself; then if he wants to hire it done he will know if it is being done according to his orders and will recognize the symptoms when anything goes wrong. It may take a little time and get one’s hands somewhat soiled, but it pays in the long run, not alone in the saving of labor but in the absence of annoyance when out on a trip. It is far from pleasant to have to stop along a hot roadside to make repairs which should have been done in the garage, with probable delay and consequent upsetting of the schedule. Therefore, it behooves the owner to look after these things before starting out and to learn his car so well that he will anticipate troubles and by removing causes save time and money.