5 Symptoms Of A Bad Distributor Cap (& Replacement Cost)

If you have an older vehicle, it’s likely that it runs with a distributor. With a faulty distributor, the car simply doesn’t run as it should because this vital component supports the motor’s current and connects the plugs to the ignition coil. Here are some symptoms that indicate a defective distributor cap. This will help you to determine whether this is your problem.

We also discuss where and how to locate the distributor cap. If you want to prolong the life of your car, then you'll know what it costs to replace the distributor cap. Let’s take a quick look at the possible signs:

Trouble starting your car in rainy, foggy conditions is the most obvious sign of a defective distributor cap. The engine may also stall or shake. A common sound is a clicking or creaking noise. You might also notice a check engine warning light.

Below is a list that explains the symptoms most commonly associated with a poor distributor cap.

Bad Distributor Cap Symptoms

1. Start Trouble

You will have difficulty starting your engine if the distributor cap becomes worse. The problem will be most noticeable in winter when temperatures fall. 

Cold temperatures can cool the cap or freeze it. The sudden heat that can result from trying to turn the engine on may cause cracks. To avoid this, it’s best to keep your vehicle parked in a garage during colder months. 

2. Shaking

It could be the distributor cap that is causing your car to vibrate or shake. It might appear most obvious when your car starts or is in gear.

You will feel the shaking throughout your vehicle. This can be a sign that the distributor cap has failed. 

3. Stalling

It could be the distributor cap. The distributor has a rotating rotor inside that delivers voltage to the car. It must work properly to ensure it continues to run.

A crack or clog can cause the rotor to stop spinning. It can lead to stalling and backfiring. 

4. Squealing Noises

A distributor cap that makes squealing or grinding noises is another indicator. This issue creates an unusual sound that is easily distinguishable from other distributor caps.

Check the cap of your distributor for grease or dirt. You can hear the noise of yelling because there is an obstruction in air circulation. 

5. Make sure your engine light is on

You can have trouble even if your car is older. This light can indicate any of a number of problems.

You can evaluate other symptoms to determine if your distributor cap has a problem. If the Check Engine Light comes on with other symptoms we’ve touched on, you can bet on a faulty cap. 

Function of an Distributor Cap

A lot of voltage is generated when the engine turns on. This voltage moves into the ignition coil and the electrode of the distributor’s rotor. This is the part that replaces the current ignition system for vehicles.

As the distributor rotates, the power is transferred to the electrodes by the cap. The cap transfers electricity with the aid of wires to various spark plugs. 

Each time the cylinders require a spark to ignite fuel/air mixture, this process is performed. If this component is not functioning properly, ignition can be difficult or impossible. 

Distributor Cap Location

Under the car's hood, you will find the distributor cap. You will need to look for the black, gray or red plastic component when you lift up your hood. It's usually located in the middle of the engine.

The distributor cap looks like a crown, with blue or black cables connecting to the spokes at the top. The spark plug wires are black and blue, which transfer the power to the plugs.

If you can’t find the distributor cap, you can follow the spark plug wires to see where they attach. You can also check your owner’s manual to help you locate it. You should replace the cap if it looks worn or cracked.  

Distributor Cap Replacement Cost

Distributor cap replacement cost for labor and parts is between $70 and $130. Depending on the vehicle, you can expect to pay between $25 and $60 for parts. You will need to pay $45 to $70 for labor, if necessary. 

You can easily replace your distributor cap with a few simple tools and some general knowledge. This will allow you to save money on labor. You must label every spark plug wire you take out. Otherwise, it could end up making your life more difficult than you thought.