KEKOSENE AND GASOLINE ENGINES 



455 



By having at hand a condensed chart showing most of the pos- 

 sible causes of the various irregularities, considerable time will 

 often be saved by using it as a reminder. With all the possible 

 causes in mind, a little reasoning and perhaps a few tests will 

 nearly always enable one to reach the correct conclusion. The 

 chart shown on this page shows the most common causes of 

 engine troubles and it is hoped that gas engine operators may 

 find it of value for reference. It is suggested that it be cut out, 

 pasted on a piece of cardboard and kept in a convenient place 

 for use when needed. 



A TROUBLE CHART FOR INTERNAL COMBUSTION ENGINES 



Combus 

 tion 



Fuel 



CARBON: 



'Results from incomplete com- 

 bustion of fuel or lubricat- 

 ing oil ■which enters the 

 combustion chamber; most 

 often the latter. Oil in 

 combustion chamber is usu- 

 ally due to worn or poorly 

 fitting piston rings, too 

 much oil in crank case, or 

 being fed by oiler. 



Too rich a mixture or poor 

 carburetion is usually re- 

 sponsible for carbon forma- 

 tion from unburned fuel. 

 Poor carburetion is often 

 due to the use of a lower 

 grade of fuel than the car- 

 buretor can handle prop- 

 erly. 



LOSS OF POWER: 



Spark occurring too late. 



Spark weak because of partial 

 short circuit or battery be- 

 coming exhausted. 



Dirty spark plugs. 



Poor connections. 



Dirty timer. 



Poor or broken wiring in case 

 of magneto. 



Breaker points worn, oily, or 

 out of adjustment. 



Commutator brush dirty or 

 oily. 



Mixture too lean or too rich. 



Supply pipe partly clogged. 



Inlet valve not opening suf- 

 ficiently, due to wear. 



Water in fuel. 



Leaks around intake mani- 

 fold. 



Ignition 



'Overheating in cylinder or 

 bearings. 



Gummy, inferior or insuffi- 

 cient oil. 



Exhaust pipe partially clog- 

 ged. 



Governor out of adjustment. 



Lack of compression, which 



Motor -^ ^^^ ^^ ^"^ ^^ worn, stuck, 

 or broken piston rings. 



Scored cylinder walls. 



Leaks through and around 

 head joints. 



Valves sticking, worn, pitted, 

 or not seating properly be- 

 cause of dirt. 



In cold weather engine and 

 cooling water too cold. 



MISFIRING: 



Weak batteries. 



Poor connections. 



Dirty timer. 



Vibrator or breaker points 

 , . . pitted, dirty or poorly ad- 



Ignition ^ justed. 



Dirty or cracked plugs, points 

 of plug not properly spaced. 



Make and break points not 

 touching properly. 



Mixture too lean or too rich. 

 Fuel passage partly clogged. 

 Water in fuel. 



Fuel 



Fuel 



fLack of compression. 

 Motor s Valves stick or not working 

 L properly. 



EXPLOSIONS IN EXHAUST PIPE:* 

 Ignition flr'-^g^ilar ignition. 



t_ Poor spark, or very late spark. 

 Fuel Mixture too lean or too rich. 



* Often occurs just after starting, due to first charges not firing in cylinder and 

 passing through into exhaust pipe, where burning gases from first few explosions 

 will ignite them. 



