Older vehicles with mechanical ignition are equipped with a distributor, a shaft that’s driven by the camshaft
and is responsible for routing and delivering high-voltage spark from the ignition coil to the spark plugs. Most
newer models use coil-on-plug or direct ignition, but there are still thousands of distributor-equipped vehicles
on the road.
The distributor shaft itself will usually last the life cycle of the engine (although it can develop some play
and wear with high miles), but other distributor parts can cause problems. The distributor cap and rotor can
develop oxidation, carbon tracks or can collect condensation. Spark plug wires also wear out over time and need
to be replaced. If you find yourself replacing plug wires, remember to replace them one at a time and match the
length of the old wire and new wire to avoid crossing the wires.