CHAPTER XI
TROUBLES
Practice and experience are the best instructors in keeping the car running, and the operator quickly acquires the ability to recognize the source of trouble from the action of the engine in failing to deliver power, or from the manner in which it stops. Each part of the mechanism may be counted on to give trouble, and the possibilities are numerous, but in general it may be said that an interference with the proper operation of the engine may be laid to the failure of the ignition system or gasoline supply, a defect of the combustion space in not retaining the pressure, or the overheating of the engine.
IGNITION TROUBLES
The ignition system is the greatest producer of trouble, and the reason is usually difficult to locate. Any interference with the flow of the current, or leaks by which it evades passing over the entire circuit, will cause irregular running or the stopping of the engine, and the circuit must be maintained in the best possible condition in order to prevent these as much as possible. The wires should be well insulated, the insulation of the secondary circuit being heavier than that of the primary because of the higher pressure of the current that must be retained. The constant vibration to which the wires are subjected requires the use of cable composed of a number of strands of fine wire rather than a single heavy wire, for the latter is much more liable to be broken; but in securing the end of a cable under a nut, great care must be exercised that all of the strands are bound. A single strand is hardly noticeable, but if it comes into contact with uninsulated metal, it will permit the current to leak. In making connections, the best plan is to solder the end of the cable to a copper or brass terminal which holds the strands secure, and gives a firm bearing for the nut. Before making connections the terminals should be scraped bright, and after running the nuts down firmly, covered with vaseline to prevent corrosion. Corrosion of copper or brass produces a greenish deposit (copper sulphate) which is an insulator, and when it forms between the terminals of the conductor it produces high resistance, cutting down or even preventing the flow of current. A worse effect of corrosion is to bind the nuts on the screws, preventing their removal. A loose connection presents resistance to the flow of current, and the current will flow irregularly, as the vibrations bring the terminals together or separate them. A wire broken at a terminal is easily seen, but when a break occurs inside of the insulation, it is more difficult to detect. When a broken wire is suspected, its circuit may be located by testing, and new wires laid, one length at a time, until the faulty one is replaced. It is poor economy to use cheap wire, for the best is none too good for the hard use to which it is put. The wearing away of insulation by chafing will produce a short circuit, and the wires should be prevented from coming into contact with any part of the car or engine in such a manner as to give this result.
THE BATTERY
When a battery is exhausted, or nearly so, it will not magnetize the core of the coil sufficiently to induce a current that will give a strong enough spark to ignite the mixture. The length of time that a battery should last, or the mileage that it should give, is learned from experience, and when it is exhausted in less time there is evidence that it has either been short-circuited or that the current has been used too extravagantly.
The extra source of current that should be provided should not be switched into circuit until the short circuit that exhausted the regular source has been located and removed, or there will be a further waste of current. It occasionally happens that through carelessness the battery is so connected that one of the cells is reversed, in which case the current will be reduced by the loss of the current from two cells, for the energy of the reversed cell will neutralize that of another. If both sets of battery have become exhausted by short circuit, current for further running may be obtained by connecting the two sets together in multiple, supposing that each set is, as is usual, connected in series.
An apparently exhausted dry battery will recuperate, or pick up, if allowed to stand, but a storage battery that shows 1.8 volts or less for each cell should be immediately recharged, for further use will cause fatal injury.
THE MAGNETO
The principal troubles that come to magnetos are due to lack of lubrication and the weakening of the permanent magnets. The clearance between the armature and the pole pieces between which it revolves is very small, and even slight wear of the bearings through insufficient lubrication will permit the armature to touch. The oil cups with which the bearings are provided must be kept filled, or if the parts are connected to a mechanical lubricator, the proper adjustment must be maintained.
When a magnet is permitted to stand without a piece of iron connecting the poles, the magnetism will dissipate; to prevent this, a bar of soft iron, called a keeper, is placed across the poles, the magnetic lines of force flowing through it from one pole to the other, and the strength being retained. The permanent magnets forming the field of a magneto are very strongly magnetized, and the proportion of the strength lost through misuse will be large, resulting in their being weakened to such an extent that the current produced will not be sufficient for ignition purposes. These magnets can be re-magnetized by the makers when this occurs, the magneto regaining its current-producing ability.
The strength of the magnets will be retained for a much longer period if, when the car is standing, the armature is in such a position that it acts as a keeper; this will occur when its iron core is horizontal. As the armature will be in this position when the current is being produced, it is only necessary to bring the engine to a stop at the point when one of the pistons is approaching the end of a compression stroke. On leaving the car, the low speed should be engaged and the clutch withdrawn; the engine may be cranked slowly, and the armature held in position by throwing in the clutch to hold the crank shaft when compression is nearly complete.
It is most inadvisable to take a magneto to pieces without an exact knowledge of its construction. Except for lubricating the bearings, it is best to leave it entirely alone. In setting a magneto, it must be remembered that it is not delivering current continuously, and that when the iron core of the armature is parallel to the poles of the magnets no current is produced. The greatest strength of current is delivered as the core moves into a vertical position, and revolving the armature by the fingers will show this, for during part of a revolution it will turn easily, and during the rest of the revolution there will be resistance. The engine should be cranked until a piston is near the top of a compression stroke; holding it there, the magneto gear may be meshed with that on the half-time or crank shaft in such a manner that the armature core has moved a trifle past the vertical position. This will result in the production of a current at the instant that it is necessary for the ignition of the charge. (See Appendix.)
THE COIL
There is always a small spark between the vibrator contacts of a coil, and in time the platinum will be burned and corroded, the oxide that forms being an insulator and preventing the flow of the current. In such a case the points may be smoothed with a fine flat file and polished on a strip of leather, or if too far gone for this, may be renewed by soldering a short length of platinum wire to the adjusting screw and a plate of the same metal to the blade. While this job is a delicate one, it is not beyond the range of a careful amateur.
When the insulation of the coil or condenser breaks down, as may result from overwork or long use, it should be returned to the maker, for the construction of a coil is exceedingly delicate, and repairs on it require expert workmanship. It is not advisable to take the coil apart in any way, beyond the vibrator parts, for inexperienced handling may injure it beyond repair.
THE SPARK PLUG
The spark plug is a frequent source of trouble, for the insulation may break down, or a carbon deposit may form between the points, either fault permitting the current to pass without jumping the gap. Plugs should be so made that when the parts are screwed together the strain will not come against the insulation. Porcelain insulation is brittle, and may be cracked inside the sleeve, the damage not showing on handling and inspection, but being sufficient to permit the spark to pass inside of the sleeve instead of between the points. Mica insulation is usually formed of a large number of washers squeezed together under great pressure, but the action of the heat and the presence of oil will frequently cause the layers to separate, permitting a short circuit.
The carbon deposit that fouls and short-circuits spark plugs results from a rich mixture, or overlubrication, and this should be prevented by proper adjustments. Under the intense heat the carbon bakes hard, and can be removed only by scraping or by the action of strong ammonia or gasoline. As in scraping the smooth surface of the insulation may be scratched (which would give a rough surface to which a fresh carbon deposit would cling more tightly), the removal of the deposit by ammonia or gasoline, applied with a stiff brush, is recommended.
The points between which the spark passes should be about one thirty-second of an inch apart. After long use, the corrosion due to the heat of the spark will increase this distance, when the points should be bent together. The high compression through which the spark is required to pass presents greater resistance than air at atmospheric pressure, practically in proportion to the pressure, and a current that will produce a spark outside of the cylinder may not have sufficient pressure to give a like result when the engine is running. If the pressure of the compression is four times that of the atmosphere, the current should be able to produce a spark four thirty-seconds, or one eighth, of an inch long outside of the cylinder, and for safety this should be increased four-fold.
THE IGNITER
The stationary point of the igniter is carried on the end of a screw that passes through the cylinder head or wall, and by means of this screw its position in relation to the moving point may be altered as desired. The distance between the points when they are separated should be about one sixteenth of an inch; more than this will result in the formation of a longer spark between them, and as the passage of the spark through the high resistance of the compressed charge will produce great heat, the igniter points will be burned and corroded more than need be. The adjustment may be made by loosening the lock nut on the stationary point, and running the screw down until the stationary point is in contact with the movable when the latter is acted on by the cam. The lock nut should be run down until it bears lightly against the cylinder and the point then unscrewed, the lock nut being carried with it, until the latter is about one sixteenth of an inch away from the cylinder. This gives a corresponding distance between the igniter points, and running the lock nut down firmly will secure it.
The tappet spring should be of considerable strength in order to snap the movable point from the stationary when the tappet ceases to act. Too great strength will bring the movable point against the stationary with such force that the platinum plate that it carries will be battered out of place. The principal difficulty that is encountered is the corrosion of these points, the flow of the current being decreased or stopped by the insulating film that covers them. The blow with which the two come together tends to knock this off and to keep the surfaces flat, but when they become badly worn and pitted they must be filed smooth.
The bearing in the cylinder wall in which the movable point rocks is made after the manner of a valve; the opening must be tight in order to prevent the leakage of compression, but sufficiently free to move as the cam acts on the tappet. This joint cannot be lubricated with oil because of the heat, and the two parts must therefore be kept as smooth as possible. To attain this result they are ground together as engine valves are ground.
THE TIMER
The spring that keeps the revolving part of a timer in contact with the stationary part must be of sufficient strength to squeeze out the vaseline with which the timer is packed, as otherwise the grease will form an insulating film between them, preventing the flow of the current. The timer must be securely attached to its shaft, for if it is loose the contacts will be made at the wrong time, and the sparks will not occur in the combustion space at the correct intervals. All of its parts and connections should be as firm as possible. The rods with which the stationary part is connected to the control lever on the steering column should be provided with adjustments by which lost motion due to wear may be taken up. There are usually several joints in these rods, all of which may wear loose, and if there are no means by which they may be kept tight, the lever will move a considerable distance before the timer will respond. It is often possible to remedy this by placing coil springs in such positions that they take up the lost motion. A timer should be so set on the half-time shaft that the revolving contact is just touching the stationary contact when the piston is at its highest point in the cylinder on the compression stroke, the control lever being in nearly its most retarded position.
As dirt will interfere with the action of a timer, the cover should always be in place and tightly secured.
THE SECONDARY DISTRIBUTER
A secondary distributer will give trouble through loose contacts, dirt, or the splitting of the spark, the effect of the last being the passing of the spark from the revolving part to two or more contact points instead of but one. Particles from the carbon brush in wearing off may stick to the insulating ring between the contacts and form a path, or a strand of wire may project, producing the same result.
THE SWITCH
Loose switch parts will prevent the flow of the current or give a vibrating contact, and should be frequently looked after. If the switch is mounted on metal, as is occasionally the case, a loosening of the parts or the wearing of the insulation will result in a short circuit that is difficult to locate because the good condition of the switch is usually taken for granted.
GASOLINE TROUBLES
Commercial gasoline is frequently dirty, carrying particles of matter that will stop the fine passages and openings of the carburetor, or containing water, the presence of which will prevent the proper operation of the engine. Dirt may be removed by the use of a strainer made of fine wire gauze, and water may be separated by filtering the liquid through chamois skin, the gasoline passing through and the water remaining. It is advisable to have a strainer and trap placed in the piping that connects the tank with the carburetor to form the lowest point of the system, the gasoline passing through it and being cleansed of dirt and water.
THE TANK
The tank of a gravity feed system is always provided with a small hole or vent, usually drilled through the filling cap, through which air may enter to replace the gasoline that is drawn off in the running of the engine. If this hole becomes plugged with dirt, the escape of the gasoline will reduce the pressure in the tank to such an extent that further flow will be prevented, and the engine will stop with all of the symptoms of a lack of gasoline. On opening the tank for the purpose of investigation, the air supply will be renewed, and the engine will again run, to stop slowly as before. Clearing the hole will relieve the condition. This vent may also cause trouble in permitting water to enter and contaminate the gasoline, this being liable to happen when the car is washed.
The pipe by which the gasoline flows from the tank to the carburetor should project slightly above the bottom of the tank, to prevent sediment from being drawn into it.
As gasoline rots rubber rapidly, hose should never be used to conduct it, nor should joints be packed with rubber. Copper and brass are attacked by gasoline less than other metals, and should always be used in preference to iron, which is corroded by the liquid. Joints may be made tight by the use of shellac or soap.
THE CARBURETOR
Besides the possibility of getting out of adjustment, the greatest trouble with a carburetor comes from the clogging of the passages and openings with dirt. When dirt enters, it clogs the gasoline inlet valve and prevents it from seating properly, the float chamber being flooded as a result. When the level in the float chamber is raised, more than the required amount of gasoline flows out of the spray nozzle, and the mixture that is produced is too rich. This will also result from the bending of the valve stem or the wearing of the seat, either of which will prevent the proper shutting-off of the flow when the correct level in the float is reached.
A flooding float chamber may also be caused by a float that is out of adjustment on its stem or too heavy. In the course of time the gasoline will cut a hole through the metal of a float and leak in, and leakage will also occur if the soldered joints open, the float then becoming too heavy and not closing the gasoline inlet valve at the correct time. These holes will be too small to permit the gasoline to be poured out, but by placing the float in hot water, the gasoline will be evaporated and driven out as a gas. In repairing a float, as little solder as possible should be used in order that the weight of the float may not be greatly altered. A cork float will become soggy and heavy if the varnish coating is damaged and the gasoline soaks in.
Carburetors are built so that the float valve and spray nozzle may be easily cleaned, for by withdrawing plugs fine wire may be run through them. When a carburetor is taken apart for more thorough cleaning, the position of the gasoline and air adjustments should be remembered, in order that they may be replaced in approximately the correct positions, thus saving time in making the adjustments that will be necessary.
The main air intake should be kept clean, especially when it is covered with a wire gauze screen. Dirt will reduce the size of the opening, and the air that enters will not be sufficient to give a mixture of the correct proportion. The screen should be kept clean and free from oil, for the latter is a dust collector.
COMPRESSION TROUBLES
A leak in the combustion space will reduce the compression by permitting the fresh mixture to escape during the compression stroke, and will also give an escape for the pressure resulting from the combustion, the pressure on the piston being reduced in consequence. The most frequent cause of leakage is worn valves, the intense heat tending to warp the disks and to roughen their surfaces, the exhaust valve being especially liable to this as it is surrounded by the hot gases during the time that it is open. A badly fitting spark plug, igniter stem, relief cock, or other opening into the combustion space will produce the same result. Whenever possible, these parts should be fitted with copper asbestos washers, which are soft enough to squeeze into the inequalities of the surface, at the same time resisting the heat and pressure.
When piston rings or cylinder walls are cut or scratched by running without oil, the pressure will escape into the crank case, which, while warm when the engine is running properly, will be heated to a very noticeable degree under these circumstances. The only remedy is the use of new piston rings and the reboring of the cylinder. Piston rings, being of cast iron, are brittle, and must be handled carefully. To place them in position in their grooves, thin strips of steel, like pieces of a hack-saw blade, should be bound to the piston, covering all but the lower groove. The ring for this groove can then be slipped on, and when it is in position the steel strips moved upward to expose the upper grooves, one at a time.
Piston rings are usually prevented from revolving around the piston by pins driven into the piston between their ends; if these are not provided, the turning of the rings will bring their ends into line, and the pressure will leak through them. The appearance of the rings is the best indication as to whether they are permitting leakage; if they are tight, they will be smooth and polished all around, but if there is leakage, they will be streaked with black carbon deposit.
Other losses of compression may be due to a cracked piston, cylinder head or wall, the former being indicated by a hot crank case and the latter by the presence of water in the cylinder and crank case.
COOLING TROUBLES
The failing of the cooling or lubrication systems will permit the engine to heat, and if continued will produce disastrous results. The radiator of a water-cooled engine should begin to heat shortly after the engine has started, and will rapidly become warm all over, thus showing that the water is circulating properly. A failure of the circulation may be due to a clogged pump or passage, and the cause should be located and removed without delay. Dirt in the water is the most usual cause of the failure of the pump, and also of the stopping of the circulation in the gravity system. A strainer should be fitted to the filling cap of the radiator to remove bits of wood, leaves, sand, etc. The connections of the water system are frequently made of rubber hose, and this in rotting will free bits of rubber that will prevent the flow. A difficulty occurring at the clamps that attach the hose to the metal pipes is the tearing off of a strip of the rubber lining, which closes the passage after the manner of a valve.
The fan must be kept running correctly, and if belt-driven, the belt must be kept tight and the pulleys free from oil that would permit slipping.
Water that has been heated freezes much more readily than water that has not, and therefore the water system of an automobile must be carefully guarded against low temperatures. A freeze of the water may crack the water jackets or split the radiator, either of which will require the laying up of the car for repairs. The best protection is to draw off the water if there is the slightest danger of freezing, drain cocks being provided at the low points of the system for this purpose. If this is not practicable, a solution of four pounds of calcium chloride to the gallon of water, mixed hot and allowed to cool, may be used, and it will stand a temperature of 15° F. below zero without freezing.
The flanges or corresponding parts of an air-cooled motor should be kept clean, for dirt will prevent the free radiation of heat.
A lack of lubricating oil, either through the failure of the supply or the clogging of the pipes, will cause the engine to heat and the piston to stick or seize. When the car is new, it is better to supply too much oil than too little, but when the bearings have smoothed down the supply may be reduced. The operation of the engine is the only indication as to whether it is receiving a proper amount of oil, and rather than run the risk of underlubricating the piston rings and cylinder walls, it is better to have enough to produce a faint smoke at the exhaust pipe. This will show that the engine is receiving a little more than is necessary. Too much oil in the cylinder will foul the spark plug, and as this would prevent the passing of the spark, it is to be as much avoided as too little.
When the lubricator pipes are clogged, the easiest method of clearing out the obstruction is to force air through them by means of a foot pump.