Removal spark plugs
1. Grasp the spark plug wire tip and pull it off the spark plug. Do not pull on the wire.
2. Unscrew the spark plugs with a spark plug wrench and place them in the order of the cylinders.
3. If the spark plugs are very tight, do not use force, otherwise you may strip the threads on the cylinder head.
4. Warm up the engine and remove the spark plugs. Be careful not to burn yourself.
5. When installing, never screw cold spark plugs into a warm engine, otherwise you will not be able to unscrew them later.
6. Spark plugs with sealing ring should be tightened to a torque of 25 Nm. If a torque wrench is not available, screw the spark plug in by hand until the sealing ring of the spark plug fits snugly against the mounting point. Then tighten the spark plug with a spark plug wrench by a quarter of a turn (90°).
7. For used spark plugs with an already compressed sealing ring, tighten it with a spark plug wrench by 15°, this will be enough.
Note: Recommendation: To ensure that the spark plug unscrews easily, you can apply a small amount of graphite from a soft pencil to the threads or coat them with a thin layer of heat-resistant copper grease. If you apply regular grease, the spark plug will burn to the threads of the cylinder head.
Spark plug diagnostics
The appearance and color of the spark plug electrodes allow you to find out whether the engine is working properly. Before doing this, you should warm up the engine well on a high-speed highway. Checking after a short trip can lead to erroneous conclusions.
- The top of the thermal cone of the insulator is light gray to brownish in color: the injection system is in good condition, the engine operates economically.
- Heavy deposits: may be caused by additives in engine oil or fuel, or increased oil consumption due to damaged valve stem seals. Changing the brand of oil, fuel, and valve stem seals may help.
- Black, soot-like deposits: spark plug not warming up to self-clean at high temperatures due to frequent short-distance driving, incorrect fuel combustion temperature, too high carbon monoxide content.
- The top of the thermal cone of the insulator is painted whitish: the ignition timing is set incorrectly, the ignition timing adjustment is not working properly and, accordingly, the knock sensor is damaged.
- Melted spots on the middle and side electrodes: overheating due to carbon deposits in the combustion chamber, overheated valves, faulty ignition timing adjustment, or overheating due to poor cooling.
- Fracture of the top of the insulator thermal cone: at the initial stage it is a thin, hair-thin scratch: detonation combustion due to poor fuel, malfunction of the ignition timing adjustment, faulty knock sensor, insufficient engine cooling or lean mixture.
- Yellowish film on the top of the insulator's thermal cone: gasoline and engine oil additives have formed deposits that condensed under sudden and full engine load and became electrically conductive. This is a manifestation of the consequences of misfiring. Do not immediately load the engine at full power after frequent short-distance trips.
- Oil layer on the electrodes and inner surfaces of the spark plugs: piston rings, valve guides or oil-deflecting caps are faulty.
- If the engine starts poorly or stalls, although the spark plug looks normal, the spark plugs may still be the cause. An accurate diagnosis can be made using an oscillator in a car repair shop.
Gap between communication electrodes
Original article is on the portal (RENAULTBOOK)
The working mixture and the waste mixture cause corrosion on the metal electrodes of the spark plugs, and the high voltage when the spark jumps tears off a small particle of metal, as a result of which the gap between the electrodes of the spark plug increases over time.
If the gap between the electrodes is too large, a higher secondary voltage of the ignition system is required, and this can lead to misfiring. The engine may not start at all. Therefore, bend the side electrode of the spark plug if the gap is too large.