How to Clean Distributor Cap: Symptoms and How to Avoid Them?

If you are a car owner or have petrol heads in the 20th-century era, then this article is for you. There is a high probability that your car was equipped with a distributor. A distributor is one of the essential parts of the engine management system of all cars in this era.”The main job of the distributor is to route the high voltage coming from the ignition coil to the spark plugs in the correct firing order and at the right time

The distributor always consists of a rotor rotating inside a distributor cap. On top of the distributor is a shaft. This shaft is driven by camshaft gear. The rotor is connected to the ignition coil with a spring-loaded brush in the distributor cap. To connect the voltage, the second end of the rotor passes by the metal contacts in the cap when there is a high electric current.

The voltage can go through a very small area between the rotor arm and spark plug contacts in the cap due to the high voltage created by the ignition coil. This answers the question of what a distributor is and how it works. However, you have to be cautious when it comes to maintenance. So, what are the faults in these parts? What are their symptoms? How can we avoid transmission faults? How to clean a distributor cap? All this information is found in this article.

Clean Distributor Cap

How to clean Distributor cap Step-by-step guide:

The distributor cap protects the distributor’s internal parts. It holds the contacts and posts between the internal rotor and spark plug wires. Due to the necessity of this part, it carries the voltage to the spark plugs. One of the main reasons for the periodic maintenance of your car is to clean the distributor cap. Here is how to do it and how to clean distributor points to ensure perfect contact.

To see the process with a more clear view, I recommend that you watch this video to make things easier.

Step 1: Plug Out the Cables- The first thing you need is to locate the distributor. Label the spark plug cables to help you bring them back in the same order. You can then pull the cables gently out from the distributor cap.

Step 2: Get the Cap Out- Unscrew two screws on the side of the cap and try to release it by pulling it up gently.

Step 3: Clean the Terminals- Using a soft piece of abrasive, rub the contact terminals to remove any carbon build-ups and oxidation on the metal terminals. Oxidation may cause contact to stop or frail.

Step 4: Use Contact Cleaner- Spray some contact cleaner on the internal contacts of the distributor cap.

Step 5: Dry Out- If you have a compressed air source, apply the compressed air through the cap. This will help it to dry faster. You can also use a clean rug and carefully rub it until the cap is completely dry.

Step 6: Assemble- When you are sure that you did the job right, assemble back. Put the distributor caps into place. Connect the Spark plug wire back correctly in the order that you marked before in step 1.

What are the symptoms of a bad distributor cap?

If you clean the distributor cap and it still fails to work, there must be a problem with it. Do you need to understand when to replace the distributor cap? And what are the signs of a worn-out distributor cap?

There are many symptoms points for a bad distributor cap. Since it is a crucial part of the vehicle’s mechanism, the car will not run smoothly with a bad distributor cap.

Starting Problems: Cars that have a bad distributor cap can face many problems running and starting, especially in the cold weather and low temperatures. Low temperatures may cause the cap to cool down or freeze and may crack when hit with sudden heat.

Stalling and Backfire: The other symptom is having problems while coasting with the car like stalling or hear backfires from the exhaust. This is a sign that you have a broken distributor cap. It could also be due to the failure of the rotor, which distributes voltage to the spark plug, not sending enough voltage.

Shaking: If you have a malfunctioned distributor cap, you will most probably experience shaking and trembling problems. The engine does run smoothly because the distributor cap and rotor do not distribute the voltage riotously and in the right power stroke of the cylinder.

What causes corrosion on the Distributor cap?

Many people report that when they perform some maintenance in their vehicle and when they pulled up the distributor cap, they find a strange build-up. It could be crud at the end of each spark plug wire terminal or corrosion on distributor cap terminals. After research and seeking advice from some experts, we found that these phenomena happen for some reason.

The first reason is that water vapor and moisture in the crankcase rise the distributor shaft, and then all the humid air is collected inside the cap. After that, the car cools down, the air filled with water vapor condenses and reacts with the metal contacts.

The second reason is that the alternator overcharges the battery system. It then produces battery acid that may build up inside the distributor cap, causing corrosion.

Finally, the wires may be porous and attract water into the distributor cap. This may lead to corrosion. This, therefore, means that you need to replace the distributor cap gasket if you notice a loose distributor cap. For you to get rid of corrosion, you should clean the distributor cap with wd40.

How do you fix moisture in a distributor cap?

If you notice that your distributor cap is collecting moisture, it means that something is wrong. It is a sign that it needs some maintenance. If you fail to give it enough attention, it might lead to malfunctions of your vehicle. This is a guide on how to fix it the right way.

Every time you disassemble the distributor cap, do not forget to mark the spark plugs cables. This will help you to assemble them back in the right way.

After removing the cap, clean the inside of the cap using a clean, dry rag and then leave it in a warm area to dry out. If you have compressed air, you can use it to decrease the drying time.

It is advisable always to change the distributor cap seal with a new one to avoid getting the same problem. For extra protection, apply a silicon seal around the base of the cap and replace the wires in the proper order. You can then start the car to make sure it is running perfectly.

Final Words:

In this article, we got to know about the distributor and why it is a crucial element in the ignition system of cars. We have also seen how to take care of the distributor cap and the symptoms of the worn-out cap. The article also explains how to test for a bad distributor cap and diagnose it yourself without the need for an expert. It is always recommended that you check your distributor cap now and then. Check if it has cracks. If need be, clean to remove the corrosion. This will guarantee you safe trips and avoid bad situations in your vehicle.

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Hi there, I am R. Hasan Tito, a mechanic, and owner of this website. My friend and I created this website to share our knowledge, expertise, and experience with our fellow mechanics' community and car users. I am a specialist and certified automotive mechanic (Both Heavy Commercial and Private Cars). I worked as a Mechanic and Mechanic Supervisor for over fifteen years at Global Rebound Automotive companies - Toyota, TATA, BMW, Nissan, TVs, and Others. Now, I enjoy my new role of leading a team of automotive experts (in their respective fields) and publish new content on a regular basis on my website and social media.

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