- Candle wrench, available in the on-board tool kit or commercially available.
- 316i/3l8i: It is also recommended to purchase special pliers, such as HAZET 1849, to facilitate the removal of spark plug tips.
- 320i/325i: Screwdriver, 10mm socket.
The following wear parts must be purchased:
- Spark plugs of the recommended type.
- 320i/325i: 6 paper spacers for ignition coils as needed.
Withdrawal
- 316i/318i: Remove all spark plug tips, pulling on the tip instead of the wire. Said pliers facilitate removal.
318is:
Remove the cylinder head cover by turning both plastic clips ¼ turn with a coin.
Pull out the spark plugs with plastic tongs. The tongs are located as an on-board tool on the left next to the spark plug tips.
Models 320i/325i/328i:
- Remove the oil filler cap.
- Remove plugs from securing bolts -arrows, unscrew 2 bolts located under plugs. Remove the cylinder head trim.
- Remove the connectors from all ignition coils, to do this, remove the connector brackets.
- Loosen the bolts securing all ignition coils, pull out the ignition coils. Attention: There are ground jumpers on the ignition coils of the 3rd and 6th cylinders. When installing, they should be screwed to the same places.
Blow out the spark plug recesses in the cylinder head with compressed air to prevent dirt from getting into the threaded holes when the spark plugs are removed.
Remove all spark plugs using the special spark plug wrench.
Inspect spark plugs. With some experience, the appearance of the candle can determine how the engine works.
The following rules apply:
Electrodes and insulator
- *Grey = correct carburetor adjustment and normal spark plug operation.
- * Black color = rich mixture.
- * Light gray = lean mixture.
- * Lubrication = failure of the spark plug or insufficient sealing of the piston rings.
Check spark plug insulators for leakage currents. Leakage currents leave thin, uneven traces on the surface. If traces of leakage currents cannot be completely removed, replace the spark plug.
Clean the spark plugs with a brass brush or sandblast.
Installation
All motors except four-valve: Check electrode spacing with feeler gauges. Set value: 0.8-0.9 mm. On new candles, the interelectrode distance is usually set correctly.
To adjust the distance between the electrodes, bend the ground electrode. To do this, there is a simple, practical tool, in the absence of which you can lightly strike the electrode from the side. When bending, rest a small screwdriver against the edge of the thread of the candle, but not against the central electrode, so as not to damage it.
Clean the threads on the spark plugs with a clean cloth.
Screw the spark plugs into the cylinder head by hand as far as they will go. Attention: Do not skew candles.
Tighten the spark plugs to 25 Nm.
Attention: If a torque wrench is not available, then it is necessary to tighten the spark plug with a spark plug wrench by about 90° (¼ turn. Spark plugs that have been in use must be turned back by approx. 15°. Spark plugs that are too tight may break off when they are removed or the threads in the cylinder head may be damaged. In this case, the spark plug holes need to be repaired with UTC or Heli-Coli inserts.
Models 316i/318i/3l8iS: Connect spark plug tips according to ignition sequence 1-3-4-2. Check by shaking the reliability of fastening of candle tips.
Models 320i/325i/328i
Screw on the ignition coils, while correctly installing the paper gaskets.
Check the position of the spark plug tips and install the ground jumpers of the 3rd and 6th cylinders.
Install covers. Installation is carried out in the reverse order.
Checking electrical connections
- Check the security of all electrical connections on the ignition coil and on the ignition distributor.
- Replace damaged terminals.
- Clean rusted connections with a wire brush or sandpaper and spray with contact spray.
- The contacts must not be wet, otherwise clean the contacts and spray with a contact spray.
- Bend the ignition wires at a large angle and check for cracking. Replace all ignition wires if necessary.