(_d_) _Is the engine very stiff to turn over?_
Stiffness is due as a rule to lack of oil on the cylinder walls, caused by absence of oil in crankchamber or the film of oil on the cylinder walls having been washed off when _priming_ the engine with petrol in attempting to start it. If a connecting rod is bent, or the crankshaft distorted or a piston ring broken, stiffness will also be noted. Very often by removing the valve caps and pouring a teaspoonful of oil or paraffin into each cylinder the engine may be freed by vigorously turning the starting handle by hand until the cylinders and pistons are well lubricated.
(_e_) _Is there any sign of an attempt to fire the charge_ such as an occasional puff of smoke from the exhaust or inlet, or an occasional jerk round of the engine as you turn the starting handle, or an occasional “bang” in the exhaust box?
If the ignition is “_on_” and the carburettor jet clear, the compression good and the engine quite free, yet there is no sign of a “fire” from any of the cylinders, it is possible that air is leaking into the induction pipe through a faulty joint or any one of the following ignition troubles may have occurred:—
(_f_) _Defective sparking plug or plugs._ This may arise from water or oil or dirt between the plug points; or from faulty insulation in the body of the plug. To test whether the plugs are at fault an easy method is to take a screwdriver with a wooden handle and place the metal blade on the terminal of the plug, letting the point come about one thirty-second of an inch from the metal of the cylinder or any of the pipes; when the engine is turned by hand the spark will be seen to pass across this improvised gap if the magneto and leads are in order.
The high tension cables may be broken, or disconnected, or short-circuited. The _earth_ wire may be short-circuited (i.e., in electrical contact with some other wire or metal fitting). There may be a short-circuit in the ignition switch.
The low tension contact breaker lever may be jammed so that the make and break is inoperative, or one of the carbon brushes may have got broken. Occasionally one finds the magnets of the machine have lost their power; or there is some electrical defect in the armature or condenser. The battery may have become exhausted. The trembler blade may be stuck up. Water may have found its way on to the high tension electrode or into the safety spark gap.