2. Before proceeding with the procedure, wait until the engine has completely cooled down.
Models with ignition distributor
If there is no factory marking, mark the BB wires of the spark plugs yourself with adhesive tape in accordance with the numbering of the cylinders (1 to 4, counting from the timing chain). Disconnect wires from spark plugs (in order to avoid damage to the contact terminal, pull only on the rubber tip, and in no case on the wire itself!).
Models without ignition distributor
![](https://www.skodabook.ru/img/remain/0904.jpg)
1. Disconnect the wiring connector at the end of the ignition coil unit.
2. Using a wrench, remove the two socket head bolts under the block.
![](https://www.skodabook.ru/img/remain/0905.jpg)
![](https://www.skodabook.ru/img/remain/0906.jpg)
![](https://www.skodabook.ru/img/remain/0907.jpg)
3. Gently pulling forward, remove the coil assembly from the spark plugs.
All models
1. Before removing the candles, in order to prevent debris from entering the cylinders, small debris and dirt should be removed from the candle niches - clean the niches with a thin brush, or blow them with compressed air (you can use a regular bicycle pump).
![](https://www.skodabook.ru/img/remain/0908.jpg)
2. Using a special key equipped with an elastic insert, turn out the spark plugs. To avoid damaging the threads, be careful not to twist the spark plugs when turning them out.
3. Analysis of the external condition of the candles can provide a lot of useful information about the degree of engine wear. If the working end of the spark plug is shiny and free from plaque and deposits, then the air-fuel mixture is too lean in the combustion chambers, or the spark plug has an excessively high glow number (heat removal from the electrodes in a hot candle is less intense than in a cold one).
4. If the working end of the plug and the central inner insulator are covered with a thick layer of sooty deposits, then the mixture is too rich. The black color of the working part of the candle, combined with traces of oil, indicates internal engine wear or excessive enrichment of the mixture.
5. Gold or greyish-brown coloration of the working part of the spark plug is evidence of the correct layout of the air-fuel mixture and the good internal condition of the engine.
6. Finally, make sure that the replacement spark plugs match the size just removed from the engine. In most cases, plugs should be flat seated and fitted with a sealing washer, however, on some 135 engines, taper type plugs used without washers are used. Installation on the engine of candles of the wrong standard size is unacceptable. If you are not sure about the selection of candles, please contact the Skoda service center for advice.
7. One of the most important parameters that determine the efficiency of sparking a candle is the size of the interelectrode gap. Nominal values of candle gaps are given in the Specifications.
8. To set the interelectrode gap, measure it with a special probe, and then very carefully bend the side electrode in the appropriate direction. Under no circumstances should you try to correct the position of the center electrode, as this may damage the internal porcelain insulator, which is fraught with the most serious consequences.
![](https://www.skodabook.ru/img/remain/0909.jpg)
![](https://www.skodabook.ru/img/remain/0910.jpg)
![](https://www.skodabook.ru/img/remain/0911.jpg)
9. Gap adjustment should be made using a special tool, which is usually mounted on the body of wire-type probes.
10. Before installing the spark plug on the engine, make sure that the contact tip of the shank is firmly seated. Also check the cleanliness of the threaded part and the outer surface of the insulator. Lightly lubricate the threads with copper grease to make it easier to unscrew next time.
![](https://www.skodabook.ru/img/remain/0912.jpg)
11. Gently thread the spark plug into the hole in the head recess.
Note. It is usually quite difficult to screw a spark plug into the threaded hole of the cylinder head without misalignment. In order to avoid damage to the threads in the body of the head made of soft aluminum alloy, it would be best to screw the candle by the length of the fuel hose, which is put on its outer insulator. In this case, in the event of a skew, the hose will simply begin to turn on the candle without any risk of damaging the thread.
12. Remove the piece of hose from the shank of the spark plug screwed into the head, then tighten the spark plug with the required force using a torque wrench.
Note. If you do not have a torque wrench handy, tighten the spark plug until it stops by hand, then tighten another quarter turn with a spark plug wrench. Install all remaining spark plugs to the engine in the same manner.
13. On models equipped with an ignition distributor, connect the wires to the BB spark plugs in accordance with the marking, then replace the top cover of the engine.
14. On models without a distributor, install the ignition coil assembly in the reverse order of the above. Tighten the coil unit mounting bolts to the required torque.