3.26. Replacement of spark plugs

Replacement of spark plugs (through 30 000 km for ethylated gasoline and through 50 000 km for unleaded gasoline) *

For definition of further intervals of conducting this check see appropriate sections of the schedule of routine maintenance of the car.


The correct functioning of spark plugs is vital for the correct and effective operation of the engine. It is extremely important that the candles corresponding to this engine were installed in the car (types of candles are given in Specifications at the beginning of this Chapter). In case of observance of requirements of Specifications, candles should not require special attention in intervals between intervals on the current shift of candles, cleaning of candles which should not be undertaken without existence of the special equipment occasionally can be necessary, otherwise it is possible to damage the working ends of electrodes easily.

The models which are not equipped with system of direct ignition

 PERFORMANCE ORDER

1. Give screws and remove a viewing cover in the center of a cover of a cam-shaft.
2. If tags on high-voltage wires of spark plugs are not visible, mark wires with 1 on 4 according to numbers, the cylinders served by them (numbering of cylinders is carried out from a distributive chain).
3. Remove wires from spark plugs, at the same time it is necessary to pull for a wire tip, but not for a wire, differently it is possible to damage the wire plug. After a detachment of all wires remove a sealing ring from a head of cylinders from the distributor and shift wires aside.

Models with direct ignition

 PERFORMANCE ORDER

1. Disconnect the plug of wires from the ignition block from a flywheel.
2. Give 4 screws fixing the ignition block to the top part of a head of cylinders. For this purpose the key hexagon will be required.
3. Where is available, give a bolt and release the holding clip of wires of the block.
4. There where is available, give a bolt and disconnect a grounding wire.
5. Carefully lift the ignition block, at the same time removing it from tips of spark plugs.

All models

 PERFORMANCE ORDER

1. In order to avoid hit of dirt and foreign particles in cylinders, it is necessary to remove dirt from the surface adjacent to candle openings by means of a brush, a vacuum cleaner or compressed air.
2. By means of a candle key, a suitable tubular key or the deep face screw-driver and the extender unscrew spark plugs. You discipline a replaceable head parallel to a spark plug, in case of moving of a head or its inclination the ceramic case of a candle can be easily damaged aside.


3. After removal of all spark plugs examine them as follows.
4. Survey of spark plugs gives good information on a condition of the engine. If the insulator of a spark plug pure and white, without deposits, indicates it too poor mix or too hot candle (the hot candle transfers heat from an electrode slowly, and the cold candle transfers warmly quickly).
5. If the tip of a candle and the insulator are covered with a thick layer of deposits of black color, it indicates too rich mix. In case the candle has black color and is greasy, then it, generally, indicates strong wear of the engine also, as well as supply of too rich mix.
6. If the insulator is covered with an easy raid of gray-brown deposits, then it indicates the correct mix and that the engine is in good shape.
7. Very important parameter is the gap of electrodes of a candle. So, if the gap is too big or too small, the size of a spark and its efficiency will be seriously reduced. The gap of an electrode has to be established according to the values given in Specifications at the beginning of this Chapter.
8. For installation of a gap of a candle measure a gap by the shchupovy measuring instrument or the wire measuring instrument.
9. Or measure a gap by the wire measuring instrument.
10. Then draw in or unbend an external electrode of a candle before exposure of the correct size of a gap. The central electrode of a candle never has to be turned in as it can lead to cracking of the insulator and irreversible damage of a candle. When using the measuring probe the gap is correct when the probe of the measuring instrument passes a gap between electrodes with a resistance.
11. In shops of automobile accessories there is always a special tool for adjustment of gaps of electrodes of candles.
12. Before installation to the place of spark plugs make sure that the carving ring is strongly fixed and that the external surface of a carving of a candle is cleared.
13. Often it is difficult to insert a spark plug into a nest on a carving. In order to avoid breaking of a carving put on a short piece of a rubber hose with an internal diameter of 7.94 mm the end of a candle. The flexible hose works as the cardan hinge, and will help to level a candle in a carving opening. At a candle perekashivaniye the hose will begin to slip on a candle, preventing thereby a possibility of failure of a carving in the head of cylinders made of aluminum. Remove a rubber hose and tighten a candle with the required effort by means of a candle key, and then a dynamometer key. Similarly establish all spark plugs.

Models with direct ignition

Install the ignition block, working as it should be the return to the procedure of removal. Tighten 4 screws with the required effort.

The models which are not equipped with direct ignition

PERFORMANCE ORDER

1. Connect high-voltage wires, observing an order of their connection according to their marking and establish a rubber ring.
2. Establish into place a viewing cover and tighten fixing screws.