Definition

1. Noun:
   • A component of an internal combustion engine's ignition system: A distributor cap is the protective cover on a distributor. Its primary function is to house the central rotor and provide insulated terminals for the high-tension wires that carry electrical current from the distributor to each spark plug in the correct firing order.

Usage

• The distributor cap is a crucial part of the ignition system in many older gasoline engines.
• It is typically made of plastic or phenolic resin to provide electrical insulation.
• A faulty or cracked distributor cap can cause engine misfires, rough idling, or a failure to start.

Examples

• Noun:
  • The mechanic removed the distributor cap to inspect the rotor and contacts.
  • A common symptom of a bad distributor cap is moisture inside the cap causing a short circuit.
  • The spark plug wires snap onto the metal terminals on the distributor cap.

Advanced Usage

• "To pull/check the cap": A common shorthand in automotive repair meaning to remove and inspect the distributor cap.
  • The engine was misfiring, so the first thing I did was pull the distributor cap.

Variants and Related Words

• Distributor (noun): The main ignition component to which the cap is attached. It contains a rotating shaft and rotor that directs the high-voltage pulse.
• Rotor (noun): The rotating arm located under the distributor cap that connects to the central terminal and distributes the spark to each outer terminal in sequence.
• Ignition coil (noun): The component that generates the high-voltage electricity sent to the distributor.

Synonyms

• Cap: A general, informal term used in automotive contexts (e.g., "The ignition cap is cracked.").
• Distributor cover: A less common descriptive synonym.

Notes on Meaning

• The term specifically refers to the itself, not the entire distributor assembly. Its core function is to route high-voltage electricity correctly and safely.
• In modern vehicles with distributorless ignition systems (DIS or coil-on-plug), this component is obsolete.

Noun

1. the cap of the distributor that holds in place the wires from the distributor to the spark plugs