The appearance of the spark plug
Examining any spark in the first place pay attention to snuff. Nagar - it is a good conductor, so it is the cause of the leakage current in the spark plug. The leakage current from a new candle is very small and does not affect the operation of the ignition system. In operation, the candle sludge thickness increases, resistance decreases and the leakage current increases. With the growth of the leakage current decreases the voltage between the electrodes of the spark plug. As a result, there comes a time when the candle stops working.
Fouling the insulator - a phenomenon the inevitable. However, finding a deposit, take the time to clean it. Please pay attention to the thickness and color. If the candle is covered with a thin layer of soot from gray-yellow to light brown in color, it can not be removed as it does not affect the operation of the ignition system. However, if the thickness of the layer of soot is high or it is dark, then a candle need to be cleaned.
On appearance of the spark plugs, you can determine if it is working candles, whether they are suitable for this engine is working well injection system, what is the condition of the working mixture and the condition of the engine (piston, piston rings, and so on).
It should be guided by the following rules.
The candle looks flawless
The heat insulator is covered with a light cone, in most cases the powder coating from gray-brown to yellow. Electrodes have, depending on the scale from the surface of the blue-yellow to brown powder coating. The inner part of the housing has a light brown or yellowish-brown to black plaque.
In this case, the motor in order. The heat of combustion of candles is correct.
Heat the cone insulator, the electrodes and the inner surface of the body, in most cases have a thick powder, black and gray velvety coating.
The reason for this is too rich fuel mixture, a lack of air, too great a distance between the electrodes, the spark is too high calorific value and is too cold during operation of the engine. As a workaround, you can offer to insert a candle on the other calorific value.
Heat the cone insulator, the electrodes and the body are covered with candles oily, shiny soot (formation of oil carbon). The reason for this may be the engine oil which has got into the combustion chamber or worn cylinders and pistons.
The thermal insulator cone is covered with dark-brown to gray-black, glassy or hard parched bloom. In most cases at the end of the thermal insulator cone are thick and glassy formation. The electrodes, especially central, have traces of aggressive action. The surface of most of the rough, corroded or swollen.
The reason may be lean fuel mixture, loose spark badly closing valves or plug with too low calorific value which when the engine overheats.
Clean the deposits between the porcelain insulator of the central electrode and the body of the candle, if possible, by means of sandblasting. Before you wrap the candle carefully clean it with thread. Be sure to pay attention to the tightening torque (25 or 30 Nm).