Bad Distributor Symptoms (Causes, diagnosis & Fixes)

Bad Distributor Symptoms (Causes, diagnosis & Fixes)

You likely have a distributor if you own one of these older cars. A distributor is a mechanical and electrical component that transmits current from the ignition coils to the spark plugs at the right time for proper combustion.

A failing distributor means that one or more spark plugs will not properly combust the air-fuel mixture once it enters the combustion chambers. The common bad distributor symptoms are hard starting, car not starting, and engine misfiring, but there are other signs you should watch out for.

In this article, you’ll learn the symptoms of a bad distributor cap, how to test a bad distributor cap, and how much to fix it. By the end, you’ll learn how to replace it. So, grab a seat while I walk you through all you need to know.

Common Symptoms of bad Distributor

Since the distributor plays an essential role in the combustion process, it has apparent symptoms when it fails. Here are bad distributor symptoms in Honda and other car models.

Car not starting

The combustion process must be complete for a car to start and run as predefined by the manufacturer. When you crank the engine, the car battery supplies electric power to the starter motor. The starter motor spins the engine. As the engine spins, it draws air-fuel mixture into the combustion chamber. The pistons compress the air-fuel mixture, and the spark plugs ignite them and cause the momentum that moves the vehicle.

If the distributor fails, it won’t supply enough electric current to the spark plugs, which is needed to ignite the air and fuel in the combustion.

Although several other issues like lousy fuel pump, dead spark plugs, alternator, fuel injectors, ignition switch, starter motor, etc., can prevent your car from starting. So, you should always diagnose your vehicle whenever you experience car not starting issues before replacing the distributor.

Stalling engine

If the engine eventually starts and it has trouble running, it is one of the symptoms of bad points in a distributor or bad rotor. The distributor has a rotor that rotates to supply electric flow, and the rotor must work fine for the vehicle to run smoothly.

If the rotor cracks or clogs with carbons, it may prevent it from rotating, which will not only cause engine stalling, it may lead to engine backfiring. Plus, clogged contact points will cause stalling and engine misfiring.

The illumination of the check engine light

The powertrain control module triggers the check engine light on the dashboard whenever it detects a problem in the powertrain. The engine firing cycle is one of the things the PCM monitors. If the distributor fails, the spark plugs will not ignite the fuel properly, causing the car computer to trigger the check engine light on the dashboard.

Additionally, if the distributor timing is too advanced or retarded, it’ll affect the engine firing cycle. When this happens, the car computer will trigger the check engine light on the dash to notify the driver of an underlying issue.

Your vehicle is vibrating

Several factors, like lousy engine mount, damaged transmission mount, wheel, and tire issues, can cause car vibration. However, vibration is one of the bad distributor symptoms in Chevy 350 and other car models. Plus, vibration can result from a misfiring engine.

Squealing noise from the distributor

Another common bad distributor symptom on 5.7 Vortec and other car models is a squealing or high-pitched noise from the distributor. This unique sign lets you know when the distributor is failing.

To confirm if the sound is coming from the distributor, remove the screws holding the covers and inspect it. The high-pitched noise comes from the distributor if you see a build-up of carbons, dirt, grease, or other contaminants.

Failed smog inspection

The distributor provides electric flow to the spark plugs but if it fails, the plugs may not provide enough spark to properly burn the fuel in the combustion chamber. The unburnt fuel will exit the combustion chamber alongside exhaust gas, which will cause you to fail emission inspection.

How to Check Bad distributors

If your vehicle uses a distributor and you notice one or more of the above signs, you have to check the distributor to ensure it is the root cause of the problem before blaming it.

Here’s a simplified step on how to test a distributor to know when it is faulty.

• Locate the distributor in the engine bay, close to no.1 or 4 cylinder on four-cylinder engines. It has plug wires that connect to the spark plugs.
• Unplug one of the distributor lead wires and place a screwdriver very close to it to create an arc. Avoid doing this with your hand to avoid injuries.
• Unscrew the bolts holding the distributor caps and inspect them for signs of cracks, damage, and corrosion.
• Ensure the firing points are not covered up with build-ups. Bad contact points will look corroded or burnt.
• Ensure the rotor is in good condition.

What causes distributors to become bad quickly

Like several car components, some factors can cause the distributor to become faulty. Here are the most common causes you should watch out for.

Corrosion

Corrosion is a common issue with most electrical components in cars. It occurs when moisture and a metallic component come into contact. It can also happen due to oxidation when your vehicle runs too hot. Other substances, like grease or deposits, fuel or oil leaks, can cause corrosion.

You can protect your car distributor from corrosion by cultivating a regular maintenance habit.

Carbon build-ups

Carbon build-up is the most common reason distributors become bad quickly. High electric flow spark in the distributor can cause build-ups and erosion on the contact points, rotor, and other parts. Carbon build-ups are typically obvious. You can see them once you remove the distributor caps.

Wear and tear

Distributors are subject to wear and tear since they are exposed to high electric voltage. Plan on replacing it every two to three years so it won’t fail when you least expect it.

How to fix bad distributors?

If you establish that you have a lousy distributor after a thorough inspection, you must fix or replace it, depending on the type of damage.

If it’s a cracked distributor cap, replacing it with a new one is the most feasible fix. But if the cap is dirty or corroded, you must clean it properly. Here’s a simplified guide on how to clean a corroded distributor.

• Remove the distributor cables. Ensure they are labeled. If not, label them so that you can reinstall them in the correct order.
• Remove the distributor cap by unscrewing the fasteners holding it in place
• Clean the contact points on the distributor cap with a bristle brush and some contact cleaner
• Dry the cleaned cap with compressed air or a clean rag
• Reinstall the distributor cap by following the reverse process.

If the problem persists after cleaning the distributor, replacing it would be the only option. To replace it, remove the lead wires, the distributor cap, and the lousy distributor. After that, lose the bolts holding the distributor in place. Install the new distributor using the reverse procedure. However, this type of job is best left to professionals because you have to time the distributor with the engine using the manufacturer’s specifications.

FAQ