Symptoms of a Bad Distributor O Ring

Distributors are essential ignition system components seen on several old model vehicles. While auto manufacturers have replaced them with coil ignition systems, you can still see them in cars produced in the last few decades. The distributor uses a shaft connector to the engine to send electrical voltage to the individual spark plugs.

They have O-ring seals that prevent engine oil leaks as the shaft spins along with the engine. If these O rings start failing, it will cause oil leaks at the base of the distributor.

This article will explain the symptoms of a bad distributor O ring and how to replace them. You’ll also learn the cost of replacing distributor O rings.

distributor o ring function

What are the symptoms of a bad distributor O ring?

The most common symptoms of a bad distributor O ring are noticeable oil leaks at the base of the distributor, rough idling, and loss of engine power.

Oil leaks

The distributor O ring function is to prevent oil from leaking from the distributor. Oil leaks at the base of the distributor are the most noticeable bad O rings symptoms.

If the O ring becomes brittle or wears out, it will not seal the space between the engine and the distributor. This will lead to motor oil leaks at the base of the distributor.

Aside from messing up the engine bay, the oil leaks will also cause low engine oil. And if this continues for a long period, it’ll reduce the motor oil level to a point it’ll cause catastrophic engine damage.

Rough idle and poor engine performance

Another possible bad distributor symptom is the rough idle and poor engine performance. This happens when the distributor itself is bad. But it can also occur in some bad O ring cases.

If motor oil leaks from a lousy distributor O ring, it may seep into important engine parts like wires and horse. This will deteriorate the horses and wires. Affected hoses and wires can lead to vacuum leaks and electrical shorts, causing loss of engine power and bad gas mileage. These are also oil-in-distributor cap symptoms.

Distributor Oil Leak Repair YouTube

How to Replace Distributor O Ring

While oil leaks from the distributor can cause you headaches, the replacement or fixing approach is straight to the point. Most often, you can quickly identify if the O ring is the cause. Here’s how you can replace a distributor O ring in simplified steps.

Step 1: Disconnect the battery cable

Disconnect the battery terminals before removing any component. Remove only the negative battery terminal or both terminals and keep them in a secure spot.

Step 2: Take off the air filter housing and the engine cover.

On most vehicles, you’ll have to disconnect the air filter housing and remove the engine cover to gain full access to the distributor. Take off these components to gain full access.

I recommend you consult your owner’s manual or service booklet to learn how to remove this ignition component. The procedures may differ from vehicle to vehicle.

Step 3: Mark the components

To avoid complicating things, mark the parts that connect to the distributor. This will help you determine the location of each part. Mixing up things will cause engine misfires, rough idling, poor acceleration, etc.

Generally, you have to number the spark plug wires and mark the position of the distributor on the engine. Use a tape marker when marking these components. Number the plug wires in the order of the cylinders they go into. This helps you know where to socket the plug wires and how the distributor aligns with the engine.

Step 4: Disconnect the spark plug wires

Disconnect the spark plug wires after you finish numbering them. Do not forget to keep them in a secure place.

Step 5: Take off the distributor

After you remove the plug wires, loosen the bolts and nuts holding the distributor in place. There are two or three bolts and nuts holding the distributor in place. Get a sizable wrench and loosen the bolts and nuts.

After taking off the bolts, wiggle the distributor out of its position. Kindly note where the distributor gear or drive faces as you remove it. You can mark the position. The gear will move when removing the O ring. Thus, you have to turn it back to its position when reinstalling the distributor.

Step 6: Pull out the old O ring and install the new one

Get a hooked O ring removal tool or tinny flat screwdriver for removing the O ring. Insert the flat end of the removal tool or the flat screwdriver and pry the old O ring. Don’t worry if the O ring breaks. You are going to replace it, anyway.

Get the new O ring and dab it with little oil before installing it. After the installation, turn it on with your hand and ensure it seats properly.

Step 7: Mount the distributor

The next step is to mount the distributor. But before doing that, check the drive or gear and ensure it is in the same position as when you removed it. Ensure the mark on the distributor and the engine aligns when installing it. This will help you maintain the distributor timing. Don’t wiggle the distributor when mounting it to avoid the gear from shifting. Hold it straight while pushing it until you hear a click from the gear.

Tightened the distributor bolts once the gear clips with the cam housing and the distributor laps on the engine.

Step 8: Reinstalling other components

It’s time to reinstall the components you removed earlier. Reinstall the lead wires according to how you numbered them earlier. After that, reinstall the air filter housing and the engine cover. Check if the air filter is dirty and clean it before reinstalling it.

Connect the battery terminals and tighten them. Check for corrosion on the terminals and clean them as needed.

bad distributor o ring symptoms

How much does it cost to replace Distributor O Ring?

With the above instructions, you can replace your O rings at home. Distributor O ring replacement costs as low as $2 or as high as $150. If you choose to replace it at home, you’ll spend only $2 to $4 to get the new O rings. But if you have a mechanic replace it, it’ll cost you $50 to $150, depending on your car model.

Final Words

This article has outlined the common symptoms of a bad distributor O ring. Oil leaks at the base of the distributor, rough idling, and poor engine performance are the signs of a lousy distributor O ring. In most cases, the only symptom you would have is the oil leaks at the distributor basement.

Regardless of the issues you experience from a worn-out O ring, you need to replace it as soon as possible. Driving with a lousy distributor O ring because it is not causing any significant issues is a bad idea. It is only a matter of time before it will lead to rough idling and poor acceleration.



While growing up, I knew I had a thing for car repairs though my parents never wanted me to learn mechanics. I always visit a mechanic garage in my small neighborhood after school. As I grew older, at age 16, I got addicted to anything automotive. My parents had to enroll me in that mechanic garage since giving up was never an option for me. As a dedicated mechanic who got into the industry from an early age, I'm graced with an addiction to diagnosing and rectifying automotive problems with ease.

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