Every car maintenance is more than just replacing consumables and troubleshooting. It is also a diagnosis that avoids breakdowns, since most of them can be prevented even at the appearance stage. Not a single fault appears on its own. This phrase applies to the entire car, especially its power unit, which consists of a gearbox and engine. The latter is a complex “organism”, whose “organs” work in harmony and understanding with each other or do not work at all, there is no third.
Over time, the engine exhausts its resource, becomes not so powerful and economical. For some, this resource is several tens of thousands of kilometers, for others, it exceeds a million. But age is not the only factor that affects engine performance. Perhaps its adjustment is simply violated, which means that the "organs" are working, but incorrectly.
The surest way is to inspect the spark plugs. A black candle can tell a lot to the right owner. First of all, you need to check why the candles are black. To do this, try to erase the black coating on the electrodes and see how tight it sits. If you can do it with your finger, then a black candle is not too scary. Here, everything can be limited to adjusting the carburetor or replacing the electronic control unit. It must be said right away that the combustible mixture entering the cylinders is too rich in gasoline. As a rule, in this case, the car can be observed puffs of black smoke, especially with engine loads. In this case, it is worth going to a service station and adjusting the fuel system in accordance with toxicity standards, this will be the surest way to eliminate this malfunction.
Another unpleasant situation that the black candle talks about is the wear of the piston rings. In this case, the oil, which serves to lubricate the walls of the cylinder, passes under the oil scraper rings, and then rises into the combustion chamber. Here it is coked at the electrodes. Black spark plugs should make you think about valve stem seals. Naturally, all engine parts have approximately the same resource, after which they need to be changed all together. So, rings and caps are just such details. In order to verify the correct diagnosis, you again need to turn to the exhaust pipe, the blue smoke from which indicates exactly this. Naturally, it will not be dark blue, but slightly bluish.
It happens that a black candle indicates late ignition, because at the moment the piston is at top dead center, it does not occur, therefore, part of the fuel remains on the electrodes. The combustion temperature in this case is significantly reduced.
In conclusion, it is worth saying that a black candle can be the result of low-quality fuel. In this case, you just need to change the gas station. Naturally, you should not rush to extremes, you must first determine the nature of the malfunction, because for different models and brands of the car, the repair price varies, and in vast limits that are simply impossible to limit.