Mercedes S-class W202

1993-2000 of release

Repair and car operation

Mercedes W202
+ 1.2. The general data
+ 2. Maintenance service
+ 3. Engines
+ 4. Greasing system
+ 5. Cooling system
+ 6. Heating, ventilation
- 7. Ignition system
   7.2. Safety precautions at repair of electronic system of ignition
   7.3. Ignition coils
   - 7.4. Spark plugs
      7.4.2. An index калильного numbers
   + 7.5. The device of a preliminary warming up of a diesel engine
+ 8. Fuel system
+ 9. Transmission
+ 10. A running gear
+ 11. A steering
+ 12. Brake system
+ 13. A body
+ 14. An electric equipment
+ 14.2. Electroschemes

7.4. Spark plugs

7.4.1. Removal, installation, check

Spark plugs should be changed every 2 year or through 30 000 km.

1. Cool the engine to temperature which is maintained by a hand.
2. Remove a cross-section pipe of the air filter.
3. The 4-cylinder engine: unscrew on a cover of a head of the block of cylinders a protective casing of wires of a high voltage (5/1).
4. The 6-cylinder engine: unscrew a protective casing of wires of a high voltage (5/1) on a cover of a head of the block of cylinders. Take ignition coils together with the connected wires of a chain of management and will put them aside.
5. Ослабьте all contact tips of spark plugs, then remove them. Thus pull only for tips, instead of for wires.
6. If probably, cautiously blow compressed air of a niche of spark plugs.
7. Unscrew spark plugs (R4) by means of a suitable candle key, or key HAZET 2776 and check up appearance ввертной candle parts. Having some experience, it is possible to draw conclusions on a working condition of the engine from this. Following rules are fair.
Electrodes and insulators:
  – cреднесерый colour – normal combustion and normal work of a spark plug.
  – Black colour – too rich gas mixture.
  – светлосерый colour – too impoverished gas mixture.
  – Violet colour – faults in work of a corresponding spark plug or bad sealing piston rings.
8. Check up measuring щупом a backlash between electrodes. A preset value: 0,8 mm.
9. For a backlash establishment between contacts unbend a lateral electrode. For this purpose knock sideways on a lateral electrode. At bending back support a small screw-driver edge of a carving of a candle, but at all the electrode middle as differently the electrode can be damaged.
10. Clear a carving on candles and in a head of the block of cylinders.
11. A hand screw in spark plugs up to reliable прилегания on a head of the block of cylinders.
The prevention

Inserting candles, do not warp them. It is necessary to pay attention to it, because at 4-klapannyh candle engines deeply sit in the nests. So it is recommended to apply specially to engines Mercedes corresponding candle key HAZET 2776.

12. Hardly tighten spark plugs with the moment 25 Н.м.
The prevention

The too hardly tightened spark plugs at their twisting can be broken off or damage a carving in a head of the block of cylinders. In this case the carving ввертной can be restored candle parts by means of UTC-inserts (or Heli-Coil).

13. Spread contact tips of spark plugs. Alternately moving there-here, check up a rigid nozzle of contact tips of spark plugs and high voltage wires.
14. The 6-cylinder engine: mount ignition coils together with nests of wires.
15. Screw protective casings on a cover of heads of the block of cylinders. Establish a cross-section pipe of the air filter and fix it шланговыми clips.

The coordination with quality of fuel

S-class engines, as a rule, require in неэтилированном gasoline for высокофорсированных engines with октановым number 96-98 (on ROZ 95). If maintenance with this fuel is not guaranteed, for example, abroad it is possible to refuel temporarily and неэтилированным irregular gasoline (on ROZ 91). The oktanovoe number defined on ROZ, specifies in detonation firmness of fuel.

At engines in volume of 2,2 and 2,8 l thanks to system of detonation regulation, the automatic coordination with corresponding quality of fuel is carried out.

At engines in volume of 1,8 and 2,0 l the coordination is carried out by means of removal levelling штеккера. Thanks to it, ignition is switched to other characteristic of ignition. This new characteristic of ignition allows to maintain the car at use неэтилированного gasoline for cars with moderately forced engines, октановое number to 92 on ROZ 91.
1. Ослабьте the plastic screw of fastening of a tank стеклоомывателя also raise this tank.
2. Remove levelling штеккер (R16/7) which is near to the regulating device of the engine (PMS).
3. If gasoline is again applied to cars with высокофорсированными engines, октановое number 96-98, spread levelling штеккер.
The prevention

At use of gasoline for cars with moderately forced engines it is possible to lower capacity and to raise the fuel expense. Aspire to avoid some full gas.

With higher октановым number, for example, "Super plus" (ROZ 98), it is possible to apply gasoline always without switching levelling штеккера.