Mercedes S-Class W-140

1991-1999 of release

Repair and operation of the car

Mercedes S-Class
+ Mercedes-Benz cars of the class S (W-140)
+ Operation manual
- Routine maintenance
   Active system of the warning of the term of approach planned THAT (ASSYST)
   Schedule of routine maintenance
   General information on control
   Check of levels of liquids, control of leaks
   Check of a condition of tires and pressure in them, designation of tires and disks of wheels, rotation of wheels
   Replacement of motive oil and oil filter
   Check of the brake system
   Check of fuel system, replacement of the fuel filter
   Check of a state and replacement of hoses of a motive compartment, localization of leaks
   Check of a condition of ridge belts of the streaming drive of auxiliary units
   Check of functioning of the cooling system and frost resistance of cooling liquid, liquid replacement
   Check of a condition of system of production of the fulfilled gases
   Check of the ATF level, replacement of the AT filter
   Visual check of tightness of automatic transmission
   Check of a condition of components of a suspension bracket and steering
   Check of a condition of protective covers of power shafts
   Check of the air conditioning system
   Lubricant of limiters of doors and cylinders of locks
   Visual control of a seat belt and block of a safety cushion
   Check of operability of headlights and horn
   Check of a state, adjustment and replacement of brushes of screen wipers
   Check of a condition of the battery, care of it and charging
   Replacement of the saloon filter
   Replacement of brake fluid
   Check and replacement of spark plugs, check of a condition of high-voltage wires (petrol models)
+ Engine
+ Cooling systems, heating
+ Power supply system and release
+ Engine electric equipment
+ Gear shifting box
+ Automatic transmission
+ Coupling
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment


Check and replacement of spark plugs, check of a condition of high-voltage wires (petrol models)

See also Section of the Spark plug of the Head Elektrooborudovaniye of the engine.

Replace spark plugs only on cold or slightly warm engine. If candles are turned out on the hot engine, the carving of the head of cylinders made of light metal can be damaged.

Spark plugs, depending on type, are replaced each 96 000 km or 160 000 km. Before work prepare all necessary tools (some producers of spark plugs deliver special tools for measurement of a candle gap):

  • Candle key of 16 mm, for example, HAZET 900AKF. HUNDRED Mercedes-Benzs apply for this purpose a candle key 3122B.
  • It is in addition recommended to get special pincers, for example, of HAZET 1849 which facilitate an otvorachivaniye of candles. Mercedes-Benz applies for this purpose an assembly key 3277A.
  • Depending on number of cylinders of the engine necessary quantity of spark plugs. The applied spark plugs are listed in Specifications. 2 spark plugs are applied to each cylinder.
  • The best way of replacement of spark plugs is preliminary purchase of new candles, adjustment of their gap and replacement of each candle in turn. Upon purchase of candles it is very important to choose those candles which are intended for the engine of your car. Information on them is provided in Specifications.

    Having near at hand new candles, let's the engine cool down completely before removal of old. During this time it is possible to examine new candles on existence in them of defects and to check candle gaps.

    The candle gap is checked by insertion of the measuring instrument of the necessary thickness between electrodes on the end of a candle. The gap has to correspond specified in Specifications. The delay has to concern each of electrodes only. If the gap does not meet standard, slightly turn in a curved part of an electrode by means of the regulator with notches before achievement of necessary size of a gap.

    At adjustment of a gap of a new candle turn in only the weight electrode basis, without touching its end. If the electrode of weight is displaced rather central electrode, by means of the regulator with notches level them. Check the porcelain insulator for existence of the cracks indicating that, the candle should be replaced.

    Engines of the M104/120 series since 01.10.93 of the issue.

    Replacement of spark plugs on series 104 engines since 01.10.93 of the issue.

    5/1 — the Cover of spark plugs
    5/2 — the Guide
    12 — the Cable pipeline
    R4 — the Spark plug
    T1-T3 — ignition Coils

    Replacement of spark plugs on engines 120 since 01.10.93 of the issue.

    T1/1-T1/6 — Sockets of coils of ignition
    A — the Cover
    In — High-voltage wires


    1. Switch off ignition.
    2. Disconnect the cable pipeline (12). On engines 120.980 the cable pipeline has to be disconnected when replacing spark plugs.
    3. Remove rubber consolidations of a cover (A) and sockets of conducting (V) (see сопр. illustration).
    4. Remove ignition coils. On engines 104 remove coils of ignition T1/1, T1/2, T1/3 with control drives and high-voltage wires of ignition.
    5. Disconnect tips of spark plugs by a soft provorachivaniye. Check an internal part of tips of VV of wires for lack of a side spark (changes of color) and check consolidations for absence of damage.
    6. Wipe tips and blow compressed air.
    7. Replace spark plugs. For prevention of damage of a carving during a wraparound of a candle use the rubber tube (internal diameter of 5/16 inch) which is put on its isolation center. In attempt of a wraparound of a candle not on a carving the rubber tube will begin to be turned on the insulator, without allowing to damage a carving.
    8. Establish tips and be convinced of correctness of their installation.

    Engines of the M119.97/98 series

    Replacement of spark plugs on engines 119.97/98

    A, In — Covers
    21 — the Spark plug
    29/1 — a fastening Element


    1. Uncover (A) and (In).
    2. Remove spark plugs (21).
    3. Apply the spark plugs recommended by the producer. Check a gap between electrodes of 0.8 mm.



    1. Compare the taken-out candle with shown in the Head Elektrooborudovaniye of the engine.
    2. Check the probe interelectrode distance. The required value of a gap is given in Specifications.

    At new candles the interelectrode distance is, as a rule, established correctly.

    3. If the carving of a candle has damage, it needs to be replaced. For this purpose there is the corresponding tool and a repair kit, in particular BERU. By means of a special drill the old carving opening can be passed. The head of cylinders for this purpose does not need to be removed. After that in a head of cylinders the new carving can be cut and by means of a special carving insert the candle is screwed. Carving inserts sit reliably and hermetically.
    4. For installation of distance between contacts turn in the corresponding mass electrode. For this purpose knock sideways on a mass electrode. At a podgibaniye you oboprit the small screw-driver about edge of a carving. Do not lean at all on the central electrode as it can be damaged.
    5. Apply a little cupriferous anti-taking structure on a carving of a new candle. Establish a candle in a head of cylinders and screw it fingers against the stop, then tighten by means of a head of a candle key. If it is possible, use a dynamometer key for tightening of a candle to be sure that it is established correctly. The effort of tightening of candles is included in Specifications.

    In order to avoid a possibility of a vvinchivaniye of a candle not on a carving put on a small piece of a rubber hose or a plastic tube its shaft. The flexible tube will work as universal - the cardan hinge, providing alignment of a candle in relation to a candle nest and in case the candle begins to warp, the hose will slip on it, without giving the chance to strip a thread.

    6. Before connection to a candle of a high-voltage (VV) wire carefully examine it on damages, corrosion of internal contact and measure resistance. If it considerably exceeds 30 kOhm/m - replace all set of wires.
    7. Connect a wire to the established new candle, again using rotary motion and holding the socket until it is put on a candle up to the end.
    8. Repeat the procedure described above for other spark plugs consistently to avoid the wrong connection of candle VV of wires.