Maintenance work on the ignition system (BMW 3 Series E30)

The electronic ignition system does not require any maintenance in principle, except for checking the contacts of the connections and spark plugs as part of the maintenance schedule.

Checking the distributor cap

Remove the distributor cap (see section "Removal and installation the ignition distributor").

The lid must be dry inside.

Check the connection contacts for damage or corrosion; if necessary, clean them with sandpaper.

Check the ease of movement and integrity of the central carbon contact. To do this, press the contact with your finger.

Check the distributor cap for leakage currents. Leakage currents leave thin, uneven marks on the surface of the distributor cap.

Wipe the distributor cap with a clean dry cloth and examine it for microcracks, replace if necessary. Finally, spray the inside of the cap with contact aerosol.

Remove the distributor rotor and check it for microcracks, also check the cleanliness of the contacts, clean them if necessary.

Lubricate the felt on the distributor shaft with a drop of oil.

Put on the distributor rotor. The rotor nose should fit into the groove on the distributor shaft. Turn the rotor in both directions, checking the reliability of its installation.

Install the distributor cap (see section "Removal and installation the ignition distributor").

Checking electrical wire connections

Check the reliability of the fastening of all electrical wires on the distributor and ignition coil.

Replace broken terminals.

Clean corroded contacts with a wire brush or sandpaper, and spray with contact spray if necessary.



The contacts must be dry, otherwise clean them and spray with contact spray.

Check for cracking by bending the ignition wires at a large angle. Replace all ignition wires if necessary.

Checking and replacing spark plugs

Spark plugs should be replaced every 20,000 km. Platinum spark plugs generally have a longer service life. They should be replaced when the central electrode is no longer visible in the insulator leg.

Disconnect all spark plug leads (in this case, you should take hold of the tip, not the wire). Removing the tips is made easier by using special pliers, for example from HAZET 1849.

Blow out the spark plug recesses in the cylinder head with compressed air and use a special spark plug wrench to remove all the spark plugs.

Inspect the spark plugs. With some experience, you can tell how the engine is running by looking at the spark plug.

The following rules apply.

Electrodes and insulator

• Gray color - correct carburetor adjustment and normal operation of spark plugs.
• Black color is an enriched mixture.
• Light gray color - lean mixture.
• Oiling - spark plug failure or insufficient piston ring sealing.

Clean the spark plugs with a brass brush or sandblast.

Check the spark plug insulators for leakage currents. Leakage currents leave thin, uneven marks on the surface. If traces of leakage currents cannot be completely removed, replace the spark plug.

If necessary, bend the central electrode at a right angle to compensate for burning.

Check the interelectrode distance using feeler gauges. Specified value: 0.7-0.8 mm.





To adjust the distance between the electrodes, bend the ground electrode.

Clean the threads on the spark plugs and in the cylinder head.

Screw the spark plugs into the cylinder head by hand until they stop.

Caution: Do not allow the spark plugs to become tilted.

Tighten the spark plugs to 25 Nm.

Note: If you do not have a torque wrench, use a spark plug wrench to tighten the flat-seat spark plug "A" by approximately 90° (¼ turn). Tighten the conical-seat spark plug "B" by approximately 15°, as do used flat-seat spark plugs.

Spark plugs that are too tight can break off when the threads in the cylinder head are turned out or damaged. In this case, repair of the spark plug holes with UTC or Heli-Coli inserts is required.