Signs of a Bad Engine: How Do You Identify and Fix It?

Signs of a bad engine are common symptoms you experience while driving that indicate a problem. These signs could be oil leakages, overheating after driving for a while, or unusual sounds from your engine.

A Black and White Image of an Engine

This article covers the symptoms of a bad engine, the causes, and how to prevent them.

What Are the Common Symptoms of a Bad Engine?

The common symptoms of a bad engine are gas leaks, knocking or whistling sounds from your engine, and overheating. Another common symptom is that your exhaust will suddenly start bringing out smoke.

Engine misfires and your dashboard light flashing are also signs that your engine may be bad.

You Keep Experiencing Engine Misfire

One of the signs that indicate a bad engine is if you notice continuous engine misfires. Engine misfires can be caused by numerous factors, all of which are signs that something is wrong with your engine. It could also mean that a particular engine component has gone bad or malfunctioned.

Engine_s Spark Plug After Misfire

If your spark plug is old or worn out, you may experience engine misfires while starting your car, as your plug isn’t active enough to start the engine. Your engine will also misfire if your ignition coil is bad. Your car won’t start if you have a bad ignition coil.

Your engine can also misfire if there is oil or water in your coil. Apart from the coil, water can also damage other parts of the engine. For instance, water in the fuel injector can also cause a misfire. You should check out these components if you experience regular misfires.

Your Engine Runs Inconsistently or Roughly

Rough idling is a common symptom of a bad engine. If your engine suddenly starts running roughly, or if you notice that the engine is jerking, you should immediately check for possible damages in your engine. Rough idling of the engine occurs when some engine components are either clogged or worn out.

Your engine can also run roughly when your spark plugs become old, causing further damage to the engine. Other problems that can cause your engine to run roughly include the wrong gasoline or if your battery is running low. If not fixed immediately, these issues could worsen your engine’s condition.

If your engine is running roughly, it usually means your vehicle is not properly burning fuel due to engine-related problems like old spark plugs, bad batteries, or worn-out valves. When your engine is rough idling, try checking your internal engine components for any bad or malfunctioning engine components.

You Have Smoke Coming From Your Exhaust

It is unusual for your exhaust to be bringing out smoke, and it is a sign of an engine problem. The smoke could be of different colors, including white, black, or blue. The smoke color usually indicates a particular engine problem, ranging from combustion issues to worn or damaged piston rings.

Smokes Coming Out of Exhaust

If the smoke from the exhaust is white, it could be that there is an issue with your engine’s coolant. If there is blue smoke, it shows that your oil is burning up due to problems related to your engine’s valve or piston ring.

If there’s black smoke getting out, it could mean an issue with your fuel injector or filter. No matter the color of the smoke, it could be a sign that something is wrong with your engine. Inspect the smoke color to know which part of the engine to check.

Strange Engine Knocking Noises Are Coming From Your Car

Hearing strange noises from your car while driving is a common symptom of something being wrong with your engine. The sound coming from your car could be a simple clicking or a knocking sound. These sounds normally alert you to a problem with one or more of your engine components.

If there’s a clicking noise while you’re driving, it could mean there’s an issue with your timing belt, or it’s not properly lubricated. The sound also gets louder when you’re speeding. If you’re experiencing a pre-ignition problem, you may also hear strange noises from your engine.

Your Check Engine Light Keeps Flashing

One of the first signs of a bad engine you’ll notice is your warning lights flashing continuously. Once the malfunction indicator light starts blinking, it’s an indication that some components are malfunctioning in your engine. Issues like misfiring cylinders or problems with the fuel delivery system can trigger the light.

Check Engine Alarm On Odometer

In most cases, the check engine indicator signals minor engine issues, while other lights on your dashboard may indicate other non-engine-related problems. Hence, if your lights start flashing, you should read the error code to confirm if your engine is going bad and know how to fix the problem.

You Are Experiencing Fluid Leaks

If you notice fluids leaking from your car, you’re likely having engine-related problems. Oil or fluid leaks usually occur when you have worn-out gaskets, seals, or cracks in your engine’s block. These leaks can result in low oil levels, causing inadequate lubrication and increased friction within the engine.

Black Fluid Leaking From Engine

What Are the Causes of an Engine Going Bad?

The causes of an engine going bad are different malfunctioning engine components, overheating, poor or insufficient lubrication, sinking the car, or inappropriate fueling. When your engine starts malfunctioning, it is important to trace the cause and fix it before the problem worsens.

Continuous Overheating Issues

Overheating is a very common cause of malfunctioning engines. When your car’s engine gets too hot, it can break down your lubricants, thereby increasing the friction. It will also cause different parts to wear out easily. The issue can also cause components in your car to expand unevenly.

Signs of Overheating in Engine

When your engine starts overheating, the cylinder head can easily warp or crack, consequently hindering your engine from maintaining proper compression and combustion. Severe overheating in your engine can even lead to a blown head gasket. This issue will result in coolant and oil mixing and reducing the engine power.

Inappropriate Lubrication of Your Engine

Key components of your engine could get damaged due to improper lubrication. Inappropriate lubrication can lead to engine problems because lubricants, such as oil, are crucial in reducing friction between moving parts and dissipating heat. Several issues can arise if the lubrication is insufficient or of poor quality.

Poor lubrication can cause increased friction and wear when metal parts in the engine keep rubbing against each other. Poor lubrication of your engine can also lead to overheating due to excessive heat buildup, a major factor that damages most car engines.

Sinking Your Engine in the Water

Another reason why your engine could go bad is if you sink the engine in water. Most components in your engine are not compatible with water, and they can easily get destroyed when soaked. To avoid sinking, don’t drive in flooded areas or leave your car in the rain without cover.

Washing Car Engine Can Ruin the Engines Malfunctions

Using the Wrong Type of Fuel

If you use gasoline on a diesel engine, your engine could knock down or develop some serious problems. This is because engines are designed to run on specific fuel types, usually gasoline or diesel. This is a common reason why some engines suddenly get spoilt without any signs or symptoms.

Stand Of Different Fuels in Station

Using gasoline in a diesel-powered engine (or vice versa) can lead to inefficient or incomplete combustion, causing poor performance, misfiring, and increased emissions. The wrong fuel type can also damage your fuel lines, filters, pumps, and injectors due to compatibility issues and the different fuel properties.

Neglecting Your Cooling System

Your engine can easily get damaged when you stop paying attention to your cooling system. This cooling system plays a crucial role in balancing the temperature of the engine. Neglecting maintenance tasks like coolant flushes and radiator cleanings can lead to coolant breakdown, which reduces the system’s ability to dissipate heat effectively.

Continuous overheating due to a neglected cooling system can damage the cylinder head, engine block, and other critical components. The issue can result in decreased engine performance, coolant leaks, and even complete engine failure. Other consequences include corrosion, blockages, and water pump failure.

How Can You Prevent Your Engine From Getting Damaged?

You can prevent your engine from getting damaged by changing the air or fuel filters regularly, changing your oil when needed, closing any leakages, and regularly scanning your car. Maintaining your engine and its components is important to avoid accidents or a total breakdown.

Always Maintain the Cooling System

Check the coolant levels while the engine is cold, as consistently low levels may indicate leaks. Also, inspect hoses and belts for wear or damage and replace them when necessary. Finally, keep your radiator clean by removing debris and insects from its fins and performing pressure checks on your cooling system.

Regularly Change Your Air Filter

When you change your dust filter regularly, you ensure that clean, filtered air reaches the engine. Also, any contaminants that bypass a clogged filter can damage internal engine components after accumulating over time. By maintaining a clean filter, you’ll prevent harmful particles from entering the engine.

New Air Filter in hands Of A Mechanic

Regularly Change the Fuel Filter

To keep your engine from getting damaged easily, avoid using your fuel filters for too long before changing them. This is because regularly changing the fuel filter reduces the load on the fuel pump and other fuel system components, extending their lifespan and preventing potential breakdowns.

The fuel filter’s primary function is to trap contaminants in the fuel before they get to the engine. These contaminants can accumulate and lead to clogs in the fuel injectors or carburetors, affecting fuel delivery. Changing the fuel filter ensures that clean fuel reaches the engine.

Change the Oil and Oil Filter Frequently

Regular oil changes pretty much guarantee that your engine is always properly lubricated, which will reduce friction-related damage. Apart from changing the engine oil, change the filter regularly as well. Fresh oil with a clean oil filter effectively removes contaminants, thus preventing their negative impact.

Check for Oil or Fluid Leaks

Regularly inspecting your car for leaks allows you to catch potential engine-related problems early and have them fixed. Identifying leaks before they escalate can help prevent issues like low oil levels, which lead to inadequate lubrication and damage to the engine.

To prevent engine damage, regularly inspect your vehicle’s engine area. Look for oil spots, drips, or wet patches. If you notice any signs of leaks, address the issue promptly by consulting a professional mechanic. Regular maintenance and vigilance can help maintain your engine’s health and prevent potentially costly repairs.

Do a Diagnostic Check When the Warning Signs Come On

When the warning light flashes, it indicates a severe problem with your vehicle’s engine that requires immediate attention. Sometimes, a damaged or loose gas cap can trigger the check engine light. Before taking further action, check that the gas cap is securely fastened.

Once you have secured the gas cap, your next step is to perform a thorough diagnostic check to determine the cause of the flashing check engine light. You should use specialized equipment to read the trouble codes stored in the vehicle’s computer system and identify the issue.


Is It Possible To Fix a Bad Engine?

Yes, it is possible to fix a bad engine, but the fixing depends on the extent of the damage. Minor issues like malfunctioning components can often be repaired. However, severe damages like blown head gaskets or internal engine component failure might require more extensive repairs or a complete engine rebuild.


Engines don’t go bad in an instant. They usually exhibit all sorts of noticeable warning signs. Here is a summary of what you’ve learned in this article:

  • The symptoms of a bad engine include overheating, leakages, and exhaust smoke.
  • The causes of an engine going bad include sinking the car, improper lubrication, and wrong fuelling.
  • You can care for your engine by regularly changing your oil and filters, and scanning your car frequently.
  • White smoke emission from your car is a sign of coolant issues.

Now that you know the different signs and causes of a bad engine, you can check and fix them anytime.

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