Components for installing spark plugs and ignition coils
1 - Ignition coil; 2 - spark plug
Attention! Spark plugs should only be replaced when the engine is cold or slightly warm. Removing spark plugs while the engine is hot can damage the threads in the cylinder head.
1. Turn off the ignition and remove the air intake sleeve together with the air cleaner housing (see chapter Power supply and exhaust systems).
2. Separate a socket of electroconducting of the coil of ignition, turn out a fixing bolt and remove the coil from a spark plug.
3. Unscrew the spark plug using a long 16 mm socket wrench, being careful not to tilt it.
4. Assess the condition of the spark plugs (see illustrations below). If necessary, correct possible problems that can be judged by the condition of the candles. Charcoal deposits on the electrodes can be removed with pressurized compressed air 588 kPa within 20 seconds, do not use a wire brush for this purpose. Checking and adjusting the electrode gap in the intervals between replacing the candles is not required.
5. Under normal circumstances, standard spark plugs should be used. «Hot» spark plugs should be installed if standard spark plugs become dirty under conditions such as frequent engine starts and low air temperatures. «Cold» Spark plugs should be installed if standard spark plugs cause detonation under conditions such as prolonged high speed driving and frequent engine revs.
6. Install new spark plugs and tighten them securely 19.6÷29.4 Nm.
7. Further installation is carried out in the reverse order. Bolts of fastening of coils of ignition tighten with effort 3.8÷4.4 Nm.
Coal deposits
Symptoms: The presence of soot indicates an over-rich air-fuel mixture or a weak spark intensity. 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 candle is caused by wear of 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 repairs and replace spark plugs.
Overheat
Symptoms: Porous, white insulator, electrode erosion and lack 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 fall into 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, replace the oil seals to prevent oil from entering the combustion chambers. Try changing the brand of fuel.
Wear
Symptoms: Rounding of 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 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 caused by a piston hitting a spark plug that is too long. Lead to cylinder failure and piston damage.
Recommendations: Remove foreign matter from engine and/or replace spark plugs.