Regarding the replacement of spark plugs, refer to the materials of Section Checking and replacing spark plugs.
Manufacturers recommend a certain type of spark plug, but suitable spark plugs with the appropriate heat rating from other manufacturers can be used.
It is advisable to clean the spark plugs with a sandblaster every 20,000 km. At the same time, set the appropriate interelectrode distance if conventional type candles are used (with one earth electrode). 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 operation of the injection system, the state of the mixture and the state of the engine (pistons, piston rings, etc.).
Since the replacement interval for spark plugs is 40,000 km, it is sufficient to clean them every 20,000 km. When screwing in the spark plugs, make sure that they are not overtightened, as the sealing washer may be damaged. Do not exceed the tightening torque of 25 Nm.