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Show mAvtonmik Simplified By an Automobile Expert. If there is anything not clear to you, ask the automobile editor about it. An answer will be published on the completion of the articles pertaining to each section under discussion. LESSON NO. 15. Failure to Start. Any of the causes of the sudden stopping stop-ping of the engine, as given in the last lesson, may be the cause of the engine refusing to start. If after cranking the engine five or six times it does not start, stop cranking crank-ing and locate the cause, or you will discharge your battery and possibly cause it. to overheat, thus ruining it. In addition to the troubles which will cause the engine to stop are others which might cause it not to start. When the engine has been running it is hot, and while running. all of the parts are moving mov-ing quickly and the suction is vigorous. When we start after it has been idle for a while, it is cold, and our cranking turns it over very slowly so that the : l!s2J parts are moving slowly and the suction is mild. What effect will the coldness and slow-cranking have on the three essentials, essen-tials, namely, compression, ignition and mixture? The compression is usually less when the engine is cold than when it warm. Can loss of compression, then, be the cause of the engine not starting? It might be, but it is the least likely of the three essentials. Your judgment will tell you whether or not you need consider compression. You know how long the engine has been run without the grinding of the valves, and whether or not it gave power when last used. Jt the engine was powerful the compression com-pression is unlikely to be at fault. Of course, if since the engine was last run you did1 some work on" it, vou mav not have gotten the parts tight, or" mnv ; have poorly set some parts, as, for example, ex-ample, the valve adjusting nut. People, in their desire to have the engine quiet, very often, set the adjustments so that , the valves do not scat properly. We can, therefore, unless our reasoning, as above, makes us suspect compression, ignore ig-nore it as a possible cause of the engine failing to start. What effect will the cold and slow-cranking slow-cranking have on the ignition svstem? If we have a battery for the 'source of the current, it practicallv will not be affected, but if we have a magneto, the slow-cranking may cause the voltage to be so low as not to give a spark. Where this is suspected as the trouble the remedy is to spin the engine vigorously. vigor-ously. Sometimes the voltage is just high enough to cause a spark to jump when the wire is held near the metal when testing the spark, vet not to be great enough to cause the spark to jump through the high-compressed mixture, mix-ture, as it takes more voltage to do this than it. does to cause it to jump across a gap in purt1 uncompressed' air. Should you suspect this to be the case vou can eee if it is bv taking out the plug and opening the points a little farther and laying it on a clean metal part of the engine. If, when cranking, you get a spark over the greater opening vou can feel tlurt you are also getting a spark across the smaller opening in the compressed com-pressed gas. Should you. after getting a spark with the original opening, not pet one with the slightlv greater opening, open-ing, then the voltage may be a little low. The thing to do then is to set the points slightlv closer than they were originally and see if the engine will start. With the exception of the low voltage, due to the slow-cranking when the car is equipped with a magneto, we mipht say that the. ignition' troubles ' which might cause failure to start arc f the same as for the sudden stopping of I the engine. e What about mixture? Here is the : cause of about 00 per cent of the start- ; ing trouble, as both the cold and slow- f era ill in g will al'fect the carbureter ac- tion. It. takes a certain amount of heat : to vaporize gasoline, and. like steam, when the vaporized gasoline strikes a f cold surface it will condense. Lot u? see what happens when we crank the S engine while it is quite cold. Due to ? the suction a certain amount of sraso- t line will be sprayed out of the cariiure- i, ter nozzle and with some air will travel j toward the cylinders, fin the way it will strike the cold mnnifoY, anH much '- of it will condense so that we will prac- ji ticallv get nothing but air into ' the cylinders and the engine will not start. 3 What can be done under these cir- j cumstaiKcs? Why. make the mixture, as I it leaves the carbureter, so rich in gasoline gaso-line that while much will condense on the way enough will reach the cvlinders - to cause the engine to start. After the engine has started the suction will be so vigorous and the speed of the mixture mix-ture from the carbureter to the cylinders cylin-ders so great that the gas will not have a chance to condense, and, moieover, much of the previously condensed gas wiil be drawn along. For this reason practically all cars are equipped with some device which will enrich the mixture mix-ture when starting, such as a device for shutting or choking off the air, thus causing an almost raw gas to be sucked up, or a device for flooding the carbureter. car-bureter. In extreme cold weather even these devices mny not be enough and the engine en-gine will have to Lie primed by pouring some raw gasoline into the cylinders through thu compression cocks or the spark-plug openings. The writer found a squirt can ,as shown in the illustration, illustra-tion, to be a great convenience for priming purposes. This can hold considerable con-siderable gasoline, and, because of the cap on the spout and the oblong shape, it could be conveniently carried in the side pockets of the door. Sometimes, when the choke valve has been used for too long a time, the en-pne en-pne will become flooded. If, after .urning the engino over while cranking a number of times, it does not start, do not keep cranking with choke valve closed or you may flood the engine. When this occurs, open tho compression cocks and, by spinning the engine, blow the excess gasoline out. In cold weather flooring is not liable to cause trouble, but it often does on warm days. Opening the throttle valve too much or not enough will often be tho cause of the engine failing to start. There is no rule which cau be given as to this as some will start only when the throttle throt-tle is wide open, while others will not start, notably the Zenith, under this condition. con-dition. Experience alone will tell you the right position -for the throttle-control lever, though with most carbureters one-third one-third open is about right for starting. Is the carbureter adjustment liable to be the cause of engine not starting? Not if the engine started easily last week aud always before. Where the engine constantly is difficult to Btart, even though it seem to run well after starting, the mixture adjustments may be at fault. The adjusting screws are about the very last thing you should touch, however. I might say here that a tendency of the engine to stop while running slowly and idle is often due to the mixture adjustment. Should our engine then fail to start, how should we proceed and what should we look for? Of course, the first thing to do is to be sure you have done all the things necessary to start it; namely, the throwing on of the switch, the feeding feed-ing of gas to the carbureter, and a gentle gen-tle priming.' Not having forgotten any of these and the day not being cold, we would by flooding the carbureter see if we are getting gasoline. If yes, then we will test the spark, as for stopping. stop-ping. If we get a spark then we can be reasonably sure that trouble is one of mixture. It may be water, so try draining the carbureter and try to start again. If the day be cold then you now can be certain that the trouble is in the failure of the gas to vaporize and reach the cylinders, and you have to resort to priming. 'Should you feel certain that the mixture is not at fault, and get the spark, then, by cranking by hand, test your compression, and that being O. K., try the spark plugs. |