Bad Distributor: Symptoms, Causes and How To Fix

A distributor in a car is a device that plays a crucial role in delivering high-voltage electric current to the spark plugs. Its primary function is to route the ignition coil’s high-voltage output to the correct cylinder at the correct time. The distributor achieves this by spinning a rotor inside a cap that has a series of contacts. These contacts distribute the high voltage from the coil to the spark plug wires leading to the spark plugs in each cylinder.

Inside the distributor, there are several components, including the distributor cap, rotor, ignition coil, and the mechanical advance system. The distributor cap is the cover that fits on top of the distributor and holds the spark plug wires. The rotor is a small rotating piece that spins inside the cap, and its tip passes close to the contacts in the cap. The ignition coil generates the high voltage that powers the spark plugs, while the mechanical advance system helps adjust the timing of the spark based on the engine’s RPM.

If the distributor malfunctions or fails, the engine’s combustion process may be affected, leading to various issues such as misfires, stalling, or difficulty starting the engine. Common symptoms of a bad distributor include engine misfires, a rough idle, difficulty starting, reduced engine performance, and decreased fuel efficiency.

Components of a Distributor

The distributor is made up of several components, including:

1. Cap: This is a plastic or metal cover that fits on top of the distributor and holds the spark plug wires in place.
2. Rotor: A small plastic or metal piece that sits on top of the distributor shaft and rotates as the engine runs. The rotor is responsible for distributing the electrical charge from the ignition coil to the correct spark plug.
3. Ignition Coil: This is a transformer that takes the low voltage from the battery and transforms it into the high voltage needed to produce a spark.
4. Points: These are metal contacts that open and close as the distributor rotates. The opening and closing of the points controls the timing of the spark that is sent to the spark plug.
5. Condenser: A small capacitor that helps control the voltage spikes created by the points when they open and close.
6. Shaft: The central shaft of the distributor that connects to the engine’s camshaft and rotates as the engine runs.

All of these components work together to control the timing of the spark that ignites the fuel in the engine’s cylinders. If any one of these components fails, it can cause problems with the engine’s performance, including misfires, poor fuel economy, and difficulty starting.

Symptoms of a Bad Distributor

Here are the symptoms of a bad distributor:

1. Engine Misfires: A misfiring engine is the most common symptom of a bad distributor. It occurs when the spark plug in one or more cylinders doesn’t fire properly.
2. Starting Problems: A bad distributor can also cause starting problems. The engine may crank, but it won’t start. This is usually due to a lack of spark.
3. Stalling: Stalling is another common symptom of a bad distributor. The engine may start but then stall shortly after. This could be due to a problem with the ignition system or fuel system.
4. Poor Fuel Economy: A bad distributor can also cause poor fuel economy. This is because the engine is not running efficiently, which can cause it to consume more fuel than necessary.
5. Engine Performance Issues: If the distributor is not functioning properly, the engine may have poor acceleration, lack power, or run rough. This could be due to timing issues, poor spark, or other problems with the ignition system.
6. Check Engine Light: If the engine’s computer detects a problem with the distributor, it will turn on the check engine light. This could be due to a problem with the distributor itself or with the sensors that monitor it.

Note that these symptoms can also be caused by other problems with the engine or ignition system, so it’s important to have a professional diagnose the issue before replacing the distributor.

The Causes of Car Distributor Damage

1. Worn Out Distributor Cap and Rotor The distributor cap and rotor are components that are prone to wear out due to constant exposure to high voltage electricity. The cap and rotor work together to ensure that the high voltage electricity is distributed to the correct spark plug. When these components become worn, they can cause misfires, poor engine performance, and eventually, distributor failure.
2. Failed Ignition Coil The ignition coil is responsible for providing the high voltage electricity that the distributor sends to the spark plugs. If the ignition coil fails, it can cause a loss of power, poor fuel economy, and engine misfires.
3. Faulty Distributor Cap and Rotor Connections The distributor cap and rotor must be properly connected in order to distribute the high voltage electricity to the correct spark plug. Loose or corroded connections can cause a loss of spark or misfires.
4. Contaminated Distributor Cap and Rotor Contaminants such as oil, dirt, or moisture can get into the distributor cap and rotor, causing electrical arcing and misfires. This can lead to premature wear and eventual failure of the distributor.
5. Worn Out Distributor Shaft Bushings The distributor shaft is supported by bushings that allow it to spin freely. Over time, these bushings can wear out, causing the shaft to wobble and the distributor to malfunction.
6. Timing Belt or Chain Failure If the timing belt or chain fails, it can cause the engine to run poorly or not at all. The distributor relies on the timing belt or chain to keep it in sync with the engine’s timing, so if the timing belt or chain breaks, the distributor may fail as well.

How to Repair a Faulty Distributor

The distributor is a crucial component in a car’s ignition system that distributes electrical power to the spark plugs in the engine. A faulty distributor can cause a variety of issues, including poor engine performance, misfires, and stalling. Fortunately, repairing a bad distributor is a relatively simple process that can be done at home with some basic tools and knowledge.

1. Diagnose the problem: Before attempting to repair the distributor, it’s essential to diagnose the issue correctly. Symptoms of a bad distributor can include difficulty starting the engine, rough idling, backfiring, and reduced power. Use an ignition timing light to determine if the distributor is functioning correctly.
2. Remove the distributor cap: Once the problem has been identified, remove the distributor cap to access the internal components. Be sure to label the spark plug wires before removing them from the cap to avoid confusion when reassembling.
3. Check the cap and rotor: Inspect the distributor cap and rotor for any signs of wear or damage. The cap should be clean and free of cracks, while the rotor should have a smooth surface and not show any signs of corrosion or pitting. Replace any components that appear damaged.
4. Check the points and condenser: Some older distributors have points and condensers that may require replacement. Check these components for wear and replace them as needed.
5. Inspect the distributor shaft: The distributor shaft can wear over time and cause misalignment. Check the shaft for any signs of wear, and replace the distributor if necessary.
6. Reinstall the distributor cap and wires: Once all necessary repairs have been made, reassemble the distributor by reinstalling the cap and spark plug wires in their proper locations. Be sure to connect the wires in the correct order to avoid issues with timing and performance.
7. Adjust the ignition timing: Use an ignition timing light to adjust the ignition timing to the manufacturer’s specifications. Improper timing can cause a variety of issues, including reduced power and increased emissions.

By following these steps, you can diagnose and repair a faulty distributor and restore your car’s performance. However, if you are not comfortable working on your vehicle’s ignition system, it’s best to seek the assistance of a qualified mechanic.