8.7.1. Appearance of a spark plug

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

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

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

At work with spark plugs observe the following rules:

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

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

- if, at the removal, any candle became 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 precautionary 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 it is necessary to tighten the moment of 30 N · m (2,0 - the liter engine) or 25 N · m (VR6 engine);

- if there is no dinamometrichesky key, a new candle wrap without effort a candle key so that the sealing ring 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 of the Volkswagen company replacement of spark plugs through each 60 000 km or each 3 years is offered. Even if spark plugs work without problems, all the same it is necessary to replace them through the recommended periods.

Gap adjustment between candle electrodes

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

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

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

In operation this gap constantly increases because of natural wear of a material of contacts. The increase in a gap conducts to growth of penetrative tension that causes violation of an iskroobrazovaniye and the increased fuel consumption.

To check gaps between electrodes it is necessary by means of round щупа. Flat щуп does not consider heterogeneity of wear of electrodes and can give a big mistake in gap measurement.

Fig. 225. Gap adjustment by means of the special tool

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