Can You Drive With a Blown Spark Plug?

It’s one of the most common problems any car driver can have: your car is working just fine and driving along nicely, and then you notice one of the many telltale symptoms of a blown spark plug – engine knocking, reduced gas mileage, hard starts, engine misfires, and rough idling.

How to tell if your spark plug has blown

Engine knocking can be identified by the characteristic “ping” sound, caused by air pockets creating a shock wave due to your spark plug no longer igniting the fuel correctly for your engine to run.

Reduced gas mileage is another symptom of a blown spark plug that is very easy to spot. You’ll notice that you are using a lot more fuel than normal and not going anywhere near as far with that fuel. Hard starts, engine misfires, and rough idling are also very common problems caused to the handling of your car by a blown spark plug.

What can you do if your spark plug has blown?

If you notice any of the issues above, there’s a good chance that your spark plug has blown. And it will definitely need to be repaired as soon as possible. But can you drive the car in the meantime? Or could you drive the car yourself to the mechanic or the garage to get it fixed?

Well, the answer is not exactly simple.

First of all, if your car has a single-cylinder engine, the vehicle is unlikely to start at all with a blown spark plug. Your car won’t be able to convert fuel inside its tank into energy in the form of heat in order to actually move the car, so you won’t be able to drive it at all in this case.

However, if your car has an engine with multiple cylinders, you may be able to drive the car. However, this does not mean you won’t have any problems. The cylinder that does not have a spark plug will not be able to convert the fuel into energy – this is the cause of the low gas mileage we mentioned earlier in the article and something that can cause you to lose a lot of money in wasted gas! As well as wasted gas, this is also going to cause the overall efficiency of your engine to plummet by a lot.

However, there are far bigger issues and risks to continuing to use your car with a blown-out spark plug that is much worse than simply losing some fuel efficiency, or wasting extra money on gas that your car isn’t using.

Risks of driving with a blown spark plug

The fuel that is still running through the engine cylinder that contains your blown, or non-functioning spark plug will eventually begin to contaminate your vehicle’s catalytic converter, and this is very bad news. What it means is that your catalyst will start running hotter and hotter, and in fact may eventually even overheat, which could even possibly lead to your exhaust becoming blocked.

If your exhaust becomes blocked or your catalytic converter becomes blocked, this could result in an extremely expensive repair bill to replace both of those parts, which is likely to be much, much more expensive than the amount of money it would have taken to simply repair your blown or non-functioning spark plug in the first place.

Even worse, if you let what we describe above happen, your catalytic converter could theoretically even catch on fire and cause your whole vehicle to be permanently destroyed beyond repair! Now that is definitely going to be a lot more expensive than simply going to the mechanic and getting your spark plug replaced as soon as you notice any issues.

Now, spark plugs usually tend to deteriorate over time and you will be able to notice when this is happening by looking out for some of the symptoms we mentioned earlier in the article – engine knocking, reduced gas mileage, hard starts, engine misfires, and rough idling. Normal wear and tear on your spark plugs are also likely to be picked up by your mechanic and your car’s regular check-ups. In all of these cases, the spark plugs should be replaced immediately before further issues are caused.

However, it is certainly possible for a functioning spark plug to blow without any warning at all, perhaps while you’re out on a long journey away from any mechanics, or when you’re driving on a motorway or the highway without much of an opportunity to stop. You may be wondering, in that case, whether it would be OK to drive for a short time with your blown-out spark plug.

Can you drive with a blown-out spark plug?

Well, that depends. You need to assess the risk. First of all, if you are able to stop and arrange for your car to be picked up by a truck, this is always the safest thing to do, both for yourself and your fellow motorists.

However, if a pickup isn’t an option, you should consider everything we have said above. Spark plugs blowing out can cause, in rare instances, vehicle fires and serious damage to your car’s engine and exhaust. If you are going to continue driving, you should ensure that your next stop is to the nearest garage or mechanic in order to get this problem fixed, and you should ensure that the mechanic is very close to your current location!

Let’s say you want to prevent your spark plug from blowing out in the future – what can you do? Well, there are actually several steps you can take to keep your car safe in the future.

Preventing spark plug deterioration

One cause of spark plug wear is engine oil flowing into the combustion chamber. If you notice the smell of burning oil coming from your car, it could be a strong indication that this is what is happening, and it may be damaging your spark plugs.

The spark plug overheating repeatedly can also end up making it wear down and potentially blow. This overheating can be caused by pre-ignition or even a cooling system that has started to malfunction.

Final Thoughts

So, back to the overall question that this article set out to answer – can you drive a car with a blown-out spark plug?

The answer is yes, it is possible (as long as you don’t have a single-cylinder engine in your car), however, it is NOT recommended and the outcome could be catastrophic and expensive. If you choose to drive with a blown spark plug, do so only as a last resort and make sure that you visit a mechanic or a garage to get the issue repaired as soon as possible.

Liam

Hi, I'm the initiator and writer of this blog. Cars were and will be my first love, and my favorite hobby, that's why I decided to start this blog and write about my discoveries and techniques to improve my cars or repair them.