85425ea0

3.1.3.1.2. Replacement of spark plugs

The correct functioning of spark plugs – one of the most important conditions of effective operation of the engine. It is necessary that on the engine spark plugs only the ordered type were established. At the serviceable engine cleaning of spark plugs – rare operation.

General information on spark plugs

There are two types of consolidations at installation in a cylinder head: with a flat saddle and elastic (steel or copper and asbestos) laying or with a conic saddle without laying. At installation of a new candle first of all it is necessary to check what consolidation is provided in a cylinder head, to specify diameter and length of a carving part. If to establish a candle with a long carving part in a head with a short carving, then the acting part of a candle will become covered by a deposit and pitches, lead deposits. The candle will overheat, perhaps oplavleny carvings. At a reversing of a candle it is possible to damage because of it a carving in a cylinder head. At a short carving part of a candle and long in a head the deposit and various deposits hammer a carving, there is its oplavleniye. After long work it is necessary to pass a tap a carving part in a cylinder head, but so that dirt did not remain in the cylinder.

Depending on purpose of a candle have a number of design features. So, screened candles with tight consolidation of a wire of high voltage are applied to the cars and motorcycles working in severe road conditions when hit on the water engine is possible and at increased requirements to the level of a radio noise. For the purpose of increase in stability of work of candles on the case several electrodes sometimes become or at all there are no side electrodes (with a floating electrode).

Depending on features of working process of a candle are carried out with the insulator drowned in the case or with the acting insulator (for combustion chambers from intensive turbolizatsiy mix in the combustion chamber).

The major parameter characterizing a candle is temperature condition of its elements, first of all the central electrode and a surface of a skirt of the insulator. The main problem during creation of a candle for the high-speed engine is implementation of contradictory requirements. On the one hand – to provide rather high temperature of a skirt of the insulator that during the long work on small loadings and idling to prevent formation on it of the deposit leading to shunting, especially at low temperatures. Upon transition to big loadings at high temperatures there is a self-cleaning of the insulator of a candle due to burning out of deposits on it. On the other hand, at high numbers of turns and big loading temperature of the central electrode and lower part of the insulator should not exceed the top limit at which there is kalilny ignition (mix ignition even before emergence of a spark from system of ignition). To a cycle ignition comes from a cycle earlier and earlier, temperature of details grows until something does not burn down – at best a candle, in the worst – the piston. So because of a small candle there can be big troubles.

How to prevent a possibility of emergence of kalilny ignition? First of all, it is necessary to watch for correct (according to the instruction) installation of corners of an advancing of ignition, without allowing too early ignition. At contact system the corner of an advancing of ignition can increase unexpectedly, for example, if jumps aside one of the soldered contacts of the breaker.

The second condition – always to fill in the gasoline corresponding to engine forsirovka level (to extent of compression, the nominal frequency of rotation, filling, etc.). The it is lower than an octane number, the tendency to kalilny ignition is more. And if after all low-octane gasoline is filled in, then it is impossible to come to big loadings at high numbers of turns.

The third condition, sometimes the most important – to establish candles with the required kalilny number according to the recommendation of manufacturer of the engine.

The designation of kalilny number at one time accepted by most the European firms on time (in seconds) is the most convenient after which at tests on special installation kalilny ignition begins. The last years most firms passed to a symbol of kalilny number of candles.

Several practical advice at the choice of candles and to their service


Having established new candles after the small run (about 1000 km), it is expedient to unscrew them, having marked number of the cylinder and to attentively examine a condition of insulators. At correctly chosen kalilny number and optimum composition of mix and coal of an advancing of ignition the insulator will be light brown, brown or light gray. Multi-colored deposits on the insulator and electrodes demonstrate availability in fuel or engine oil of a large amount of additives. A black, opaque deposit on the insulator, electrodes and the case – a work sign on the majority of the modes on the reenriched mix or too high kalilny number. It is necessary to check adjustments of the carburetor or system of injection (for example on a gas analyzer) or to establish hotter candle. The brilliant black deposit demonstrates hit in the lubricant cylinder through piston rings and the directing plugs of valves. Repair of the engine is required.

If the insulator of "snow-white" coloring – means, the candle worked at the maximum permissible thermal mode. Reasons: too earlier ignition, reimpoverishment of mix or too "hot" candle for this engine. It is necessary to check adjustments of the carburetor, the characteristic of the automatic machine of an advancing of ignition and if they are normal, to put "colder" candle. Well and the following degree of an overheat of a candle – the melted-off candle electrodes (it is good that not burned through piston bottom).

It can sometimes turn out that all candles of one brand in different cylinders have insulators, different in color. The reasons can be a little. As a rule, in carburetor engines mix (on structure) and anti-detonation additives on cylinders are distributed unevenly.

Engines meet various sizes of extent of compression for each of cylinders. And between engines of one model extent of compression differs sometimes on the whole unit. At the expense of a deviation from technological processes, materials, etc. among candles of one brand the wide spacing on the actual kalilny numbers is also observed. At a big difference in a condition of candles sometimes it is necessary even to install in one engine candles with different kalilny numbers. Always to have a stock on kalilny number in various service conditions, it is expedient to have two sets of candles and to establish in the summer "colder", and in the winter – "hot".

Lately a number of firms releases candles with the expanded thermal field of a candle. For this purpose the central electrode becomes copper, the covering from heat-resistant materials (nickel, chrome) from above is put. Sometimes and side electrodes are made of metal with good heat conductivity and a heat-resistant covering. Other original decision is production of the tiny central electrode from platinum which is not acting from the insulator. Especially "cold" candles with kalilny number 300 above for the forced engines (with турбонаддуовм, duple, etc.) are usually made with a silver electrode of small diameter and a short skirt of the insulator. Before establishing such candles, it is sometimes recommended to warm up at first the engine on "hot" candles and only then to establish "cold".

It must be kept in mind that when cleaning a candle in the sanding device the surface of the insulator collapses. Better, having turned a candle, to fill in solvent, gasoline in the case or to apply a special aerosol barrel. Then a wooden stick to clear the insulator and to blow it compressed air.

PERFORMANCE ORDER
1. Open a cowl. On models of 1,2 l remove the air filter. On models of 2,0 l with 16 valves unscrew screws and uncover high-voltage wires.
2. Mark high-voltage wires in figures from 1 to 4 (the 1st cylinder is located from a gear belt) and remove high-voltage wires from spark plugs.
3. Clear candles, using a brush, the vacuum cleaner or a stream of compressed air that will exclude hit of dirt in engine cylinders after a vyvinchivaniye of spark plugs. Unscrew candles, using a candle key.
4. Visual control of a working part of spark plugs can show a condition of the engine. If the nasal part of the isolation center of spark plugs pure and white, without raid, then it testifies to too poor mix. It also specifies that a candle too hot, that is heat from the central electrode is taken away slowly. If this is so, then it is necessary to adjust composition of fuel mix or to replace a candle.
5. If the nasal part of the isolation center is covered with a black raid, then it means that mix too rich. If the raid black and oily, then it testifies to wear of the engine and need of its check and repair. If the nasal part of the isolation center is covered with a light brown raid, then the composition of mix is optimum and the engine is in good shape.
6. The interelectrode gap of a spark plug is of great importance as at too big and at too small gap the spark size changes that leads to decrease in overall performance of the engine. The gap has to conform to technical requirements always.
7. Check of a gap is carried out by a wire template (the drawing at the left) or the probe (the drawing on the right). Correction of a gap is carried out by a podgibaniye of a side electrode. The central electrode cannot be bent at all as it can lead to breakage of the insulator and an exit of a candle out of operation.
8. For a podgibaniye of a side electrode of a candle it is necessary to use the special tool.
9. Before installation of a spark plug in the engine check that the carving was pure and all threads of a carving – whole.
10. Screw in spark plugs by hand and then tighten them the required moment.
11. For screwing up of a candle on several rounds it is possible to use a piece of a rubber hose into which on the one hand to insert the insulator of a candle and, rotating a hose, to screw up a candle on several rounds. Then it is necessary to remove a hose and to screw up a candle the required moment.
12. Connect high-voltage wires to spark plugs. On models of 1,2 l install the air filter. On models of 2,0 l with 16 valves establish a cover of high-voltage wires and fix it by screws.