Listen to Your Engine: 6 Warning Signs of a 2 Stroke Clogged Exhaust

The exhaust system is often referred to as the breathing system or lungs of your vehicle. It allows your car to ‘breathe’ efficiently by expelling toxic gases from the combustion chamber.

So when it’s obstructed, the harmful fumes remain trapped in the engine.

As a result, the engine starts overheating and it may even stall or misfire. Thankfully, blocked exhausts exhibit several signs to warn you in advance.

This brings me to my next point. 

What sort of symptoms will a blocked exhaust give?

1. Difficulty starting the car

An exhaust block has an adverse effect on your car’s performance. It makes it challenging to start your vehicle. In the worst-case scenarios, it may fail to start entirely. 

You may wonder why this happens. To understand this effect, think about the core function of the exhaust- expelling harmful gases from the car

If it’s blocked, it means that it’s incapable of letting those gases escape through the rear of the vehicle.

With these gases trapped in the combustion chamber, they’ll keep the engine from functioning efficiently; hence, making it difficult to start the vehicle.

2. Burning odors

A burning smell stemming from the engine system is usually a sign that the exhaust is blocked or leaking.

If the exhaust starts leaking from the manifold, it gets pretty hot to the point that it starts burning any plastic elements.

The manifold is located at the top end of the engine. It serves as a funnel through which exhaust gases move from the engine cylinder(s) to the catalytic converter

If this manifold is completely blocked, then it won’t allow gases to pass through efficiently.

And if it’s partially blocked, some of the fumes may start leaking and burn the surrounding plastic parts or wires.

The result is an unpleasant burning smell coming from the engine bay.

3. Check engine light turns on

Modern-day vehicles comprise an onboard diagnostic system that monitors the performance of different systems, including the exhaust. 

If there’s an excess amount of exhaust gases, it will throw off the balance of the air-to-fuel mixture.

As soon as the oxygen sensors pick up on this imbalance, they’ll trigger the check engine light. So if this light comes on, it could be signaling a clog in the catalytic converter.  

Keep in mind that a faulty catalytic converter could stem from a failure in a different part, such as a spark plug hole.

The spark plug is responsible for emitting a bolt of electricity needed to ignite the fuel-air mixture.

This ignition triggers the movement of the piston, which in turn, gets your vehicle up and running. A defective plug can affect the converter, which is why you should have your car checked by an expert.

4. Poor fuel economy

Have you noticed your vehicle has poor gas mileage? Has this decrease in fuel efficiency happened recently and suddenly?

If you answered yes, this problem is likely being caused by a clog in the exhaust. 

When harmful gases are trapped in the exhaust system, there’ll be less oxygen reaching the engine.

This then forces the engine to work harder, drawing more gasoline from the tank in the process.

The result is a less fuel-efficient vehicle. So if you happen to be making more trips to the gas station, have a professional inspect the exhaust system.

5. Unusual noise

If the underlying issue is a blocked muffler, then the most common symptom you’ll encounter is an unusual noise.

If you notice this peculiar noise specifically when you start the vehicle or when it’s in an idle state, the cause could be a clog in the muffler. 

6. Difficulty accelerating

Is the vehicle struggling to accelerate each time you hit the gas pedal? Or, is it taking longer than usual to gain speed?

If you answered yes to either of these, an obstructed exhaust could be the problem. 

It’s likely that carbon emissions are trapped in the converter, preventing the vehicle from operating efficiently.  

What two problems can be caused by a clogged muffler?

The two issues that you’re likely to experience as a result of a clogged muffler are a decrease in the car’s acceleration power and louder noise. 

The main function of a muffler is to dampen the noise emitted by the engine.

So any obstructions in this part will prevent it from playing its role. The result is that you’ll end up hearing a ton of engine noise, especially when you accelerate.  

 A blocked muffler also leads to an unnecessary increase in the exhaust back pressure. Put simply; backpressure is the opposing force that acts on the exhaust gases leaving the engine via the exhaust.

A tiny amount of backpressure is okay as it’s almost inevitable. 

But beyond a certain point, this backpressure can force exhaust gases back into the engine; hence, affecting its performance.

The most likely result from this is usually a loss or decrease in power.   

How do you unclog an exhaust?

The key to unclogging the exhaust system is figuring out the cause. The two main culprits are a blocked catalytic converter and a blocked muffler.

If the converter is to blame, you’ll notice a drop in power, difficulty accelerating, engine stalling, and excess heat coming from the vehicle. 

If there aren’t any dents in the exhaust system or loose wire connection, and the catalytic converter is working just fine, then a faulty muffler is likely to blame. 

Unclogging a catalytic converter

Follow these steps to unclog your catalytic converter:

  1. If you have been driving, first allow the engine to cool down. Once it has, use a jack to raise your car so you can access the exhaust system’s parts easily.
  2. Start by identifying the oxygen sensors and removing them.
  3. Next, remove the catalytic converter by disconnecting the bolts holding it in place. Sometimes, the bolts are too stiff to remove. If this is the case, use a penetrating oil to get them loose. 
  4. Once you’ve removed it, the next thing you should do is clean it. But before you proceed with this step, confirm that there’s no rattling sound. If there is, it means the catalytic converter is damaged from the inside, and washing it won’t make any difference. But if there’s no unusual sound, proceed with cleaning it.
  5. Using a pressure washer set to the lowest setting, clean the converter, dislodging any loose particles. Next, fill a container with a degreasing agent and soak the converter in it.
  6. Once it’s fully soaked, rinse it with the pressure washer and give it time to dry before reinstalling. 
  7. Remember to put back the oxygen sensors as well. 

Unclogging a muffler

Follow these steps to unclog your muffler:

  1. The first thing you should do is detach the muffler from the exhaust system. Simply, unscrew the bolts holding the muffler in place.
  2. Next, add your preferred degreasing detergent to a container. This cleaning solution doesn’t need to have any harsh ingredients. As long as it’s capable of eliminating any built-up oil and debris, it will suffice.
  3. Putting the muffler in the container filled with the degreaser makes up the third step. Leave the muffler to soak for a few hours (preferably overnight).
  4. Finally, rinse off the degreasing agent from the muffler and give it time to dry before reinstalling it in your vehicle.

If unclogging the muffler doesn’t improve the situation, you may have to replace it with a brand-new one.

But before you do, consult a professional mechanic.

They may be able to identify a different problem with the exhaust that doesn’t involve the catalytic converter or the muffler. 


Wondering whether your vehicle’s exhaust system is restricted?

Examples of 2-stroke clogged exhaust symptoms are unusual noise coming from the exhaust, poor gas mileage, burning smell, and difficulty starting the car or accelerating. 

In case you experience one or more of these signs, check the exhaust system to see if there’s a blockage.

If there is, follow the steps above to unclog either the muffler or the catalytic converter.


Dean Alvarez, TireForge Head Author

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