The glow number characterizes the degree of thermal load of the spark plug. The lower the glow number of the spark plug, the higher the degree of its thermal load. At the same time, the spark plug removes heat better, thereby eliminating the possibility of glow ignition of the fuel mixture. A spark plug with a high thermal characteristic has the disadvantage that its self-cleaning temperature is higher. It is more prone to carbon formation, in particular when the engine often does not reach its operating temperature during operation, for example, driving in the city, short trips in winter.
The correct glow plug rating is determined by the vehicle manufacturer. There are spark plugs with one or more ground electrodes, with different thread lengths and diameters. When replacing a spark plug, only spark plugs that comply with the vehicle manufacturer's instructions must be installed.
The average service life of a spark plug varies. The electrode material also plays a significant role. Chrome-nickel alloy is characterized by very high thermal conductivity and high corrosion resistance. Silver has the best heat dissipation, and platinum electrodes have high corrosion resistance and resistance to burning. The service life of spark plugs is between 20,000 and 100,000 km, depending on the material of the electrodes and their number.
Depending on the engine design, there are two types of seals between the spark plug and the cylinder head.
The flat seal has an outer sealing ring that is not lost and is fixed to the spark plug body. With a conical seal, no additional sealing elements are required. In cases where installation space is limited, spark plugs with a flat seating surface and a small spanner size are used in most cases. Spark plugs with a conical seating surface have smaller dimensions due to their compact design.
Spark plugs should be changed every 60,000 km.
The appearance of the spark plug can be used to draw conclusions about the operation of the spark plugs, the carburetor adjustment, the condition of the mixture and the condition of the engine (pistons, piston rings, etc.) (refer to photographic inserts).
When screwing in the spark plugs, make sure that they are not overtightened, as this may damage the sealing washer. Do not exceed the tightening torque specified in the Specifications.
Coal deposits
Symptoms: The presence of soot indicates an over-enriched fuel-air mixture or weak spark intensity. It causes misfires, makes starting difficult and leads to instability of engine operation.
Recommendations: Check for a clogged air cleaner, too much fuel in the float chamber, a stuck choke, or excessively worn contacts. Try using spark plugs with a longer insulator, which increases resistance to contamination.
Normal condition of the candle
Symptoms: Gray-brown color and slight wear of the electrodes. The glow number of the spark plugs corresponds to the type of engine and its general condition.
Recommendations: When replacing spark plugs, install spark plugs of the same type.
Oiling
Symptoms: Oiling of the spark plug is caused by wear of the H m spark plug caps. Oil gets into the combustion chamber through worn valve guides or piston rings. It causes misfires, makes starting difficult and leads to unstable engine operation.
Recommendations: Perform mechanical repairs and replace spark plugs.
Ash formation
Symptoms: Soft, brownish deposits on one or both spark plug electrodes. They are caused by the additives used in the HMW and/or fuel. Excessive build-up can lead to insulation of the electrodes and cause misfires and rough engine operation under acceleration.
Recommendations: If deposits accumulate quickly, replace the H m slag caps, which will prevent H m slag from entering the combustion chambers. Try changing the H m slag fuel.
Overheat
Symptoms: Porous, white insulator, erosion of electrodes and absence of any deposits. Leads to a reduction in spark plug life.
Recommendations: Check that the spark plug heat range is correct, that the ignition timing is set correctly, that the fuel/air mixture is not too lean, that there are no vacuum leaks in the intake manifold, and that the valves are not stuck. Also check the coolant level and that the radiator is not clogged.
Wear
Symptoms: Rounding of the electrodes with a small accumulation of deposits at the working end. The color is normal. It leads to difficulty in starting the engine in cold, wet weather and increased fuel consumption.
Recommendations: Replace the spark plugs with new ones of the same type.
Too early ignition
Symptoms: The electrodes are melted. The insulator is white, but may also be contaminated due to misfires or foreign particles entering the combustion chambers. May cause engine failure.
Recommendations: Check the glow number of the installed spark plugs, the ignition timing, and the quality of the mixture (isn't it too poor?), whether the cooling system is clogged and whether the lubrication system is functioning normally.
Detonation
Symptoms: Insulators may be chipped or cracked. Inaccurate spark plug gap adjustment techniques may also damage the insulator. Piston damage may result.
Conductive gloss
Symptoms: The insulator has a yellowish color and a polished appearance. Indicates a sudden increase in temperature in the combustion chambers during sharp acceleration. Normal deposits melt, acquiring the appearance of a varnish coating. Leads to misfires at high speeds.
Recommendations: Change the spark plugs (cooler, while maintaining the same driving style).
Splashing
Symptoms: After a long period of misfire, deposits may become loose while the combustion chamber remains at operating temperature. At high speeds, deposits flake off the piston and stick to the hot insulator, causing misfires.
Recommendations: Replace the spark plugs or clean and reinstall the old ones.
Short circuit of electrodes
Symptoms: Waste combustion products enter the interelectrode space. Solid deposits accumulate, forming a bridge between the electrodes. Leads to ignition failure in the cylinder.
Recommendations: Remove deposits from the interelectrode space.
Mechanical damage
Symptoms: Can be caused by foreign materials entering the combustion chamber or occur when the piston hits a spark plug that is too long. Leads to cylinder failure and piston damage.
Recommendations: Remove foreign particles from the engine and/or replace the piston.