Interelectrode distance of the candle "A"
Spark plugs have a thread with a diameter of 14 mm. Manufacturers recommend a certain type of spark plug, but suitable spark plugs with the appropriate heat rating from other manufacturers can be used. The distance between the electrodes of the candles is 0.7-0.8 mm and is measured in place (A), shown in fig.
Spark plugs should be cleaned with a sandblaster every 10,000 km. In this case, set the appropriate interelectrode distance. When adjusting the distance, never bend the middle electrode, as the porcelain insulator may burst.
Before unscrewing the candles, check that there are no foreign objects in the niches of the candles. Washers, bolts or pebbles in the spark plug holes will destroy the valves, valve seats or cylinder head when the engine is first started.
By the appearance of the candle, we can conclude about the operation of the candles, the adjustment of the carburetor, the state of the mixture and the condition of the engine (pistons, piston rings, etc.) (see photographic inserts).
Coal deposits
Symptoms: The presence of soot indicates an over-rich air/fuel mixture or a weak spark. Causes misfiring, difficult starting and engine instability.
Recommendations: Check if the air cleaner is clogged, if the fuel level in the float chamber is too high, if the air damper is stuck, and if the contacts are too worn. Try using plugs with a longer insulator, which increases fouling resistance.
Oiling
Symptoms: Lubrication of the spark plug is caused by wear on the valve stem seals. Oil enters the combustion chamber through worn valve guides or piston rings. Causes misfiring, difficult starting and engine instability.
Recommendations: Carry out mechanical restoration work and replace the spark plugs.
Overheat
Symptoms: Porous, white insulator, electrode erosion and absence of any deposits. This will shorten the life of the spark plug.
Recommendations: Check if it meets the requirements Specifications number of glow plugs installed, ignition timing correct, air/fuel mixture too lean, intake manifold vacuum leaks, and stuck valves. Also check the coolant level and check if the radiator is clogged.
Too early ignition
Symptoms: The electrodes are melted. The insulator is white, but may be dirty due to misfiring or foreign particles entering the combustion chambers. May lead to engine failure.
Recommendations: Check the glow number of the installed candles, the ignition timing, the quality of the mixture (isn't it too poor), whether the cooling system is clogged and the lubrication system is functioning properly.
Electrically conductive gloss
Symptoms: The insulator has a yellowish color and a polished appearance. It speaks of a sudden increase in temperature in the combustion chambers during sharp acceleration. At the same time, ordinary deposits are melted, acquiring the appearance of a varnish coating. Causes misfiring at high speeds.
Recommendations: Change spark plugs (colder, while maintaining driving style).
Closing the electrodes
Symptoms: Waste products of combustion enter the interelectrode space. Solid deposits accumulate, forming a jumper between the electrodes. Leads to ignition failure in the cylinder.
Recommendations: Remove deposits from the interelectrode space.
The normal state of the candle
Symptoms: Gray-brown color and slight wear of the electrodes. The number of glow plugs corresponds to the type of engine and its general condition.
Recommendations: When replacing spark plugs, use spark plugs of the same type.
Ash formation
Symptoms: Soft brownish deposits on one or both spark plug electrodes. The source of their formation is the additives used in oil and/or fuel. Excessive buildup can insulate the electrodes and cause misfiring and engine instability when accelerating.
Recommendations: If deposits build up quickly, change the oil seals to prevent oil from entering the combustion chambers. Try changing the brand of fuel.
Wear
Symptoms: Rounding of the electrodes with a slight accumulation of deposits at the working end. The color is normal. Causes engine start difficulty in cold, wet weather and increased fuel consumption.
Recommendations: Replace the spark plugs with new ones of the same type.
Detonation
Symptoms: Insulators may be chipped or cracked. Insulator damage can also result from inaccurate spark plug gap adjustment. May damage pistons.
Splashing
Symptoms: After misfiring for a long period of time, deposits can loosen while maintaining the operating temperature in the combustion chamber. At high speeds, deposits flake off the piston and adhere to the hot insulator, causing misfiring.
Recommendations: Replace spark plugs or clean and reinstall old ones.
Mechanical damage
Symptoms: May be caused by foreign material entering the combustion chamber or by the piston hitting a spark plug that is too long. Lead to cylinder failure and piston damage.
Recommendations: Remove foreign particles from the engine and/or replace
Since the service life of the candles is usually 15,000 km, it is sufficient to clean them every 8,000 km. When screwing in the spark plugs, make sure that they are not overtightened, as the sealing washer may be damaged. The tightening torque must not be exceeded.
To maintain engine power, spark plugs must be replaced at least once every 2 years.
Instruction. Spark plugs of the new X 22 XE engine (volume 2.2 l) require replacement every 4 years or 60,000 km.
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