Auto Manual of VW Passat B5

1.6. Spark plugs

THE GENERAL DATA

There are two types of consolidations at installation in a cylinder head: with a flat saddle and elastic (steel or medno-asbestine) a lining or with a conic saddle without a lining. At installation of a new candle first of all, it is necessary to check up, what consolidation предусмот рено in a cylinder head, diameter and length of a carving part. If to establish a candle with a long carving part in a head with a short carving the acting part of a candle will become covered by a deposit and pitches, lead adjournment. The candle will overheat, probably, оплавление carvings. At a candle reversing it is possible to damage because of it a carving in a head цилинд ра. At a short carving part of a candle and long in a head the deposit and various adjournment hammer in a carving, occurs it оплавление. After long work it is necessary to pass a tap a carving part in a cylinder head but so that the dirt did not remain in the cylinder.

Depending on appointment, candles have a number of design features. So, for cars and the motorcycles working in heavy road conditions when hit on the water engine is possible, and at increased requirements to level of a radio noise are applied экранированные candles with tight consolidation of a wire of a high voltage. For the purpose of increase of stability of work of candles on the case some electrodes sometimes become or in general lateral electrodes are not present (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 acting insulator (for chambers of combustion with intensive турболизацией mixes in the combustion chamber).

In the major parametre characterising a candle, the temperature mode of its elements is, and first of all is central го an electrode and a surface of a skirt of an insulator. The basic problem at creation of a candle for высокооборотного the engine is performance of inconsistent requirements. On the one hand – to provide the heat of a skirt of an insulator that at long work on small loadings and idling to prevent formation on it of a deposit leading to shunting especially at low temperatures suffices. At transition to the big loadings at heats there is a self-cleaning of an insulator of a candle at the expense of burning out of adjournment on it. On the other hand, at high numbers of turns and the big loading the temperature of the central electrode and the bottom part of an insulator should not exceed the top limit at which arises калильное ignition (mix ignition even before occurrence of a spark from ignition system). From a cycle to a cycle ignition occurs all earlier and earlier, the temperature of details grows until something will not burn down – at the best a candle, in the worst – the piston. So because of a small candle there can be big troubles.

How to prevent occurrence possibility калильного ignitions? First of all, it is necessary to watch for correct (under the instruction) installation of corners of an advancing of ignition, without supposing too early ignition. At contact system the corner of an advancing of ignition can unexpectedly increase, for example, if jumps aside one of напаянных breaker contacts.

The second condition – always to fill in the gasoline corresponding to level форсировки of the engine (degrees of compression, to nominal frequency of rotation, filling, etc.). The more low октановое the number, the is more propensity to калильному to ignition. Well and if all the same it is filled in низкооктановый gasoline it is impossible to leave on the big loadings at high numbers of turns.

The third condition, sometimes the most important thing – to establish candles with demanded калильным number according to рекоменда цией engine manufacturer.

The designation калильного the numbers, at one time accepted by the majority of the European firms on time (in seconds) after which at tests for special installation begins калильное ignition is the most convenient. Last years the majority of firms has passed to a symbol калильного numbers of candles.

Some practical advice for choice candles and to their service

Having established new candles after small run (about 1000 km), it is expedient to unscrew them, having marked cylinder number, and attentively to examine a condition of insulators. At correctly chosen калильном number both optimum structure of a mix and coal of an advancing of ignition the insulator will be light brown, brown or light grey. Multi-coloured adjournment on an insulator and electrodes testify to presence in fuel or engine oil of a considerable quantity of additives. A black, matte deposit on an insulator, electrodes and the case – a work sign on the majority of modes on the reenriched mix or too high калильном number. It is necessary to check up adjustments of the carburettor or injection system (for example on газоанализато ру) or to establish hotter candle. The brilliant black deposit testifies to hit in the greasing cylinder through piston rings and directing plugs of valves. Engine repair Is required.

If the insulator of "snow-white" colouring – means, the candle worked on a maximum permissible thermal mode. The reasons: too earlier ignition, repauperization of a mix or too "hot" candle for the given engine. It is necessary to check up adjustments of the carburettor, the characteristic of the automatic machine of an advancing of ignition and if they in norm, to put colder candle. Well, and the following degree of an overheat of a candle – the melted off electrodes of a candle (not burnt through bottom of the piston is good that).

It can sometimes appear that all candles of one mark in different cylinders have insulators different in colour. The reasons can be a little. As a rule, in carburettor engines a mix (on structure) and antidetonation additives on cylinders are distributed non-uniformly.

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

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

It is necessary to mean that at candle clearing in пескоструйном the device the insulator surface collapses. Better, having turned a candle, to fill in in the case solvent, gasoline or to apply special aerosol баллончик. Then a wooden stick to clear an insulator and to blow its compressed air.