Updated at: 03-03-2022 - By: micdot

Even though a coolant can help regulate the temperature, it can be dangerous if the coolant seeps into unintended places. If a coolant spills and reaches the spark plug, you may wonder what would happen. Thus, you may wonder:
Is a spark plug clogged by coolant bad? Also, what should you do in the event that it does occur to you personally? Spark plugs that have been clogged by coolant provide a considerable risk of engine misfire and internal damage. Head gasket or intake manifold leaks are often the blame for these issues. For the most part, it can ruin a spark plug and cause it to wear out far faster than it should.

Fear of coolant fouling is understandable if you’re not aware of the issue. However, all you need to pass is a single accurate answer. On the other hand, neglecting it could lead to more serious problems in the future. You’ll discover everything you need to know about a coolant-fouling spark plug in this page. As a result, you’ll be more prepared to deal with the situation if it arises. It can also help you get ready for it and keep it from happening in the first place.

Is It Normal to Have Coolant on Spark Plugs?

Coolant on the spark plugs is not a common occurrence. In order to do their job, coolants regulate the temperature of the engine’s radiator.

If the internal coolant escapes and reaches the spark plug, it can cause considerable damage that is enough to cause an engine to misfire. The insulators and electrodes of the spark plug will be coated with deposits or particles if the coolant burns. Codes can be misfired because of the hot spots created by these particles.Spark plug coolant can be identified by a chalky appearance after removal from the engine.

What Happens When Coolant Leaks Into the Spark Plugs?

Leaking coolant into the spark plugs can cause severe damage to the engine, including premature failure. For example, a coolant leak can reach the engine’s head gasket from the outside. Even the combustion chambers and the cylinder can be affected.

A noticeable leak is visible between the engine’s head and block as a result of this fact. Once the engine is shut off, the gas will go through the cylinders and into the tank. Leaks of this magnitude put your engine’s health at danger. In order to avoid more damage, you’ll need to fix it as soon as it reaches the spark plugs.

Can I Drive With Coolant in My Spark Plugs?

Your engine will be less likely to shut down if a coolant leaks into the engine and reaches the spark plugs. In other words, you can still drive even if your spark plugs have coolant in them. Even so, it’s not in your best interest. Because a coolant in a spark plug can create misfires, running the engine despite the warnings of misfires might do more harm than good to your engine.

The presence of a coolant near the spark plug or in the combustion chamber generally causes a great deal of trouble. Poor engine performance and clogged spark plugs are only two examples of how it might shorten their lifespan. A coolant in spark plugs can wear down your engine and cause major harm if left unchecked for an extended period of time. As a result, if you suspect that you have coolant in your spark plugs, you should bring your vehicle to a mechanic for repair.

Can Coolant in Spark Plugs Cause a Misfire?

Misfiring can occur if coolant is present in the spark plugs. Possibly a leaking combustion chamber or head gasket is the main source of the problem, and the fouled spark plug can be traced to one or two of the pistons in close proximity.

As the plug gradually fouls, it usually means that drivers will continue to drive their car for thousands of miles with a coolant leak. Prior to this change, if the converter became clogged, the engine would automatically shut down and no damage would be done to it.

Coolant Fouled Spark Plugs Symptoms

Check your vehicle’s symptoms to see whether your coolant has fouled your spark plugs. The following are five signs that a coolant-fouled spark plug is causing problems in your vehicle:

Engine misfires

Misfires can be caused by internal coolant problems, which can cause the spark plug to become fouled. The polluted plug may only affect one or two neighboring cylinders if the problem is caused by a leaking intake manifold or cylinder cap.

Deposits or particles in the electrodes and insulator

Pre-ignition and misfire codes can be set as a result of scorched coolant depositing on the conductors and insulation.

Chalky appearance on electrodes

When the plug is removed, the ground strap and center electrode may seem powdery. Newer coolants are less likely to build up in catalytic converters because of a decrease in phosphate, zinc, and other substances that might taint them.

Clogging in the engine

Unfortunately, this suggests that drivers will continue to drive a car with a coolant leak for thousands of miles while the plug fouls. However, prior to this change, the engine would shut off when the converter became obstructed.

Damage to other parts

If the coolant is contaminated, it is possible that the bearings will fail. The oxygen sensor and the catalytic converter may both be contaminated if coolant is used in the combustion chamber.

Coolant Fouled Spark Plug Fix

There is no time to waste if your spark plug has been contaminated by coolant. You can hire someone to do it for you, but you can also do it on your own to make it last.

It’s possible to save money by following these simple techniques to fix coolant-fouled spark plugs:

Scrape the electrode with sandpaper.

There is a sliver of metal sticking out of the spark plug’s tip (the side that goes into the engine). If the electrode is dark or tarnished, sand the bent-over portion of the electrode and the spark plug until the sandpaper reveals a perfectly smooth surface on both sides of the electrode. The electrode of the spark plug should seem to be bare metal. If it doesn’t, keep sanding it until you get the desired results. Always wear safety goggles and a dust mask when sanding.

If the electrode is highly filthy, use a file to remove it.

Change the spark plug if sandpaper isn’t doing the trick. In a pinch, a little file can be used to remove a significant amount of carbon from the electrode. Insert the tool into the gap between the plug and the wire and press it back and forth to clean the metal.

Scrape the threads using a wire brush.

The threads of your spark plug may have been clogged with oil or dirt, making reinstallation difficult. Wire brush the threads at an angle to the spark plug to remove the bulk of the accumulated gunk.

The brush will follow the threads of the plug in this manner. Scrape it from a new angle for maximum effect.While using the wire brush, wear protective clothing to avoid being stung by it. To get the best  results, the threads need to be free of most buildup.

Clean the plug with brake cleaner and a soft cloth.

It’s easy to find brake cleaner in spray cans at your local auto store, and it can be used to clean a variety of vehicle parts. Additionally, it evaporates quickly, allowing the components to dry more quickly. After cleaning the plug and threads with brake cleaner, use a clean towel to remove any remaining debris.

Spark plugs that are extremely dirty can be cleaned using brake cleaner and scraping with the scrubbing brush. Using a towel, thoroughly clean the plug after removing all brake cleaners that have absorbed oil and debris from the surface.

Carry on with the procedure for every spark plug.

Once the first spark plug has been cleaned and reinstalled, reattach the spark plug cable to it. When you’ve finished with all of them, you can go on to the next.


To summarize, a coolant-fouled spark plug indicates the presence of a problem that must be addressed as soon as feasible. This can lead to engine misfiring and possibly internal damage if your spark plugs become clogged with coolant. The most prevalent cause of these problems is a leaking head gasket or intake manifold. In addition, it might cause a spark plug to wear out faster than it should, resulting in a premature failure.

As a last resort, you might save money by repairing the problem yourself. It’s a simple procedure, but it helps to keep your spark plug and your engine in general in good shape.