8.7.1. Appearance of a spark plug

Spark plugs have diameter of a carving of 14 mm. The manufacturer recommends certain candles, however it is possible to use also candles and other manufacturers with corresponding warmth of combustion.

Distance between electrodes of spark plugs are presented in the table of adjustments and the control.

Before turning out candles clear wells in which there are candles that after removal of candles the dirt has not got to apertures for them. For removal of candles it is necessary to use only specially for this purpose intended key, and wires ВН on engine VR6 can be removed from spark plugs only the special tool.

At work with spark plugs observe following rules:

- At removal of wire ВН from a spark plug do not pull for a wire, but only for a tip of wire ВН;

- After removal of candles combine them in sequence of an arrangement of cylinders;

- If, at the removal, any candle has become attached, it is not necessary to apply force as it is possible to strip a thread in the head of cylinders made of an easy alloy. In this case as an exception try to remove a candle, having warmed up the engine to working temperature, observing safety measures;

- Before installation of new candles it is necessary to wait, while the engine will cool down. Otherwise the carving will be tightened too strongly (because of thermal expansion of a material of a head of the block of cylinders);

- Spark plugs should be tightened the moment 30 Н·м (2,0 litre engine) or 25 Н·м (engine VR6);

- If is not present динамометрического a key a new candle turn without effort a candle key so that the sealing ring has sat down on the place then tighten it for 90 ° a candle key. If establish old candles tighten them still approximately on 15 °.

In schedules of maintenance service of company "Volkswagen" replacement of spark plugs through each 60 000 km or each 3 years is offered. Even if spark plugs work without problems, equally it is necessary to replace all of them through the recommended time intervals.

Backlash adjustment between candle electrodes

Fig. 224. A backlash between central and lateral spark plug electrodes. Щуп should be inserted into a crack between electrodes

Before spark plug installation check up and adjust a backlash between central and lateral electrodes (fig. 224).

This operation needs to be spent before winter operation of the car. The backlash size between electrodes of candles should be within 0,7—0,9 mm.

In operation this backlash constantly increases because of natural deterioration of a material of contacts. The backlash increase conducts to growth of penetrative pressure that causes infringement искрообразования and the raised expense of fuel.

To check backlashes between electrodes it is necessary by means of round щупа. Flat щуп does not consider heterogeneity of deterioration of electrodes and can give the big error in backlash measurement.

Fig. 225. Adjustment of a backlash by means of the special tool

To increase or reduce a backlash between electrodes it is possible only подгибанием a lateral electrode, by means of the special tool (fig. 225). For this purpose put on a tool hook a lateral electrode and cautiously bend or unbend it.