BMW Coupes and Sedans 1970-1988 Repair Guide

Rotor and Distributor Cap



See Figure 1

To prevent scraping the skin off your knuckles, slide a thin piece of cardboard or equivalent down between the engine and firewall.

  1. Disconnect the high tension wire from the top of the distributor cap and place aside.
  3. Unclip the two retaining clips which secure the distributor cap to the distributor body. Once unclip, lift the cap up.
  5. If replacing the distributor cap, tag each individual wire as to its location on the cap. Then carefully remove the wires. Plug the wires, in their correct order, into the new distributor cap.

Never remove a spark plug wire by pulling on the wire. Always remove a spark plug wire by grasping the boot.

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Fig. Fig. 1: Early clip-type distributor cap-2002 model

  1. If you are not replacing the distributor cap at this time, carefully inspect the metal contact points on the inside of the cap. Some wear is acceptable, but excessive wear, in the form of grooves or burnt contacts, indicates that the cap should be replaced.
  3. To remove the rotor cap, pull the rotor straight up. With the cap off, check the condition of the lubricating wick at the center of the rotor shaft. It should be moist with lubricating oil. If it is not, add several drops of oil to the pad.

To install:
  1. Align the tab on the rotor with the groove on the rotor shaft, then slide the rotor cap on to the shaft. Wiggle the rotor to make sure the alignment is correct. If it is not correct, the rotor will move from side to side.
  3. If you are installing a new distributor cap, and have not already installed the spark plug wires into their correct locations, do this now. Leave the high tension wire to the coil off.
  5. Position the distributor cap on to the distributor body making sure the tabs on the cap and body align correctly. In the event they do not align correctly, you will be unable to fasten both retainer clips.
  7. With the cap positioned, secure by fastening the two clips.
  9. Connect the high tension wire to the distributor cap. Start the vehicle and check for proper operation.


Check the cap and rotor for signs of burning, carbon tracks or excessive corrosion on the terminals. Do not try to clean the terminals. The cap and rotor should be replaced at the same time.

  1. Disconnect the high tension wire from the top of the distributor and the coil.
  3. Remove the distributor cap by prying off the spring clips on the sides of the cap.
  5. Examine the condition of the cap. If it is cracked or the metal tip is excessively worn or burned, it should be replaced.