The Birmingham age-herald., 1918-06-09

of overheating. If for any reason the thermostat fails to act when the water gets hot so that the passages remain closed and the water is prevented from circulating. oyerheating will quickly re- suit, The function of the thermostat, it must be remembered, is not to help cool the water after it gets hot, but to heat it when it is cold.
 Perhaps the most common cause Of overheating is the presence of carbon deposits in the cylinders of the engine. In fact, overleating is one important indication that carbon deposits have been formed in the cylinders and on the pis- ton heads. As a matter of fact, over heating due to carbon is generally ac- companied by knocking, bac<firing and a sort of general debility of the motor, loss of power is the common descrip- tion.
 CARBON
 Carbon in the cylinders causes pre-igni- ton. That is to say, the explosion oc- CUTS before the piston has reached top dead center, which causes knocking of no doubtful nature. The outstanding par ticles of carbon become incandescent and continue to glow after the explosion has taken place The incoming gas charge touches these red-hot particles and is ignited instantly, without waiting for the intended spark Naturally an en- zine that has very heavy carbon de- posits requires frequent replenishment of it's water It makes no difference how the spark lever is moved, the incan= descent carbon particles in the cylinders cause ignition quite regardless of the spark. Therefore, the only cure for over heating induced by this condition is to have the carbon removed. In cases where overheating develops while the car is on an extended tour, carbon re- rnoval can be attended to in some of thc shops that make a speciality or the work. when the tourists are stopping for the night. Every city has a garage or repair shop that will attend to this work.
 But overheating may have other fun- damental causes than these, The trn- ing of valves and ignition often plays a considerable part in this trouble, not to mention carburetion. If carburetion is poor, so that an unsatisfactory mix ture is fed to the cylinders, the fuel will burn instead of exploding and the effects will be the same as if one had run with a retarded spark. The mix ture burning slowly, instead of exploding quickly comes in contact with greater area of cylinder wall than it should. greater volume of heat is passed through into the cooling water and the fesdh is overheating.
 CARBURETION
 The modern carbureter mas such wide range of adjustment that there should be no trouble in finding Just the right mixture not only to avoid over heating. but to get maximum power and snap out of the engine Car owners Wno have tried the experiment of using either kerosene or a mixture of kerosene ana gasoline, have probably had more or less trouble from overheating and knocKins. In this case the trouble can be pretty certainly cured by reducing the com pression, placing a plate between the cylinder head and the motor block or under the block, or more easily by ln- stalling one of the devices which Will feed water with the fuel.
 Valve and ignition timing. as men toned above, do play part in causing oyerheating However, faulty valve and ignition timing is not a condition that develops suddenly, while the car IS on | the road it is something that has ex- | isted for considerable time. Unless the | car owner understands the subject oi , retirning. he had better leave the matter | to the service station,
 l Faulty fabrication will cause oyerheat- 1 ing matter that I pointed out at the beginning of this article. If the oil film l that separates the moving parts is elm | mated, the intense friction that results generates terrific heat. Also, if an oi l not adapted to the service is employed l the film will break down. perhaps no' entirely, but enough to allow the nov l ing parts to rub slightly and this, too 1 will cause overheating.
 | Much of the distortion of cylinders and pistons k due simply to running l while overheated. The periods of such
 running may be individually short. but
 the effect Is cumulative. Sooner or later the cylinders are worn oval and