WHAT CAUSES ENGINE KNOCK & HOW TO PREVENT IT | BISWAS AUTOMOBILES

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What Causes Engine Knocking and How Can You Prevent It?

If you've ever heard a ticking or knocking sound coming from your engine, you're not alone. Many car owners experience this issue — and it’s often ignored until it’s too late. That knocking noise under the hood can signal serious engine trouble, and in some cases, lead to complete engine failure.

At Biswas Automobiles, we help drivers in Dhaka figure out what’s wrong with their vehicles before it becomes a costly problem. Today, let’s talk about engine knock — what it is, what causes it, and most importantly, how you can prevent it.

What Is Engine Knock?

Engine knock is a strange, repetitive sound that usually happens when the air-fuel mixture inside your engine’s cylinders doesn’t burn the right way. Instead of a smooth burn that powers your car, the fuel ignites too early or unevenly. That causes pressure spikes, which make the parts inside your engine hit or "ping" against each other.

This noise usually gets worse when you accelerate or the engine is under load. Over time, engine knock can damage spark plugs, pistons, and even your entire engine if it’s not fixed.

Why You Should Never Ignore Engine Knock

That knocking noise isn’t just annoying — it’s a red flag.

If left unchecked, engine knock can:

• Lower your engine performance
• Cause engine overheating
• Damage your spark plugs, bearings, or cylinder walls
• Trigger the check engine light
• Lead to full engine replacement

Once the damage starts, it spreads quickly. What starts as a noise can soon cost you thousands in repairs — or leave you stranded on the road.

How to Recognize Engine Knock

Watch (and listen) for these signs:

• Ticking, pinging, or knocking sound while driving
• A check engine light that comes on or stays on
• Sluggish acceleration or reduced power
• Engine temperature gauge rising
• Poor fuel economy

Modern cars also have a knock sensor that helps detect knocking early. If this fails, you may not get a warning until real damage happens.

Common Causes of Engine Knock

Engine knock can come from several issues under the hood. Here are the eight main causes, explained in simple, clear language so you understand what might be happening inside your car.

1. Low-Octane or Poor-Quality Fuel

Your engine needs fuel with the right octane level so the air‑fuel mix burns at the correct time. If you use low-octane or poor-quality fuel, the mixture can ignite too early. This creates pressure spikes that lead to a knocking sound. Many newer engines need higher octane, so always check your owner’s manual or ask a technician at Biswas Automobiles.

2. Worn or Dirty Spark Plugs

Spark plugs ignite the compressed air-fuel mix. When spark plugs are worn, dirty, or have the wrong gap, the ignition timing becomes weak or uneven. This causes misfires, rough idling, and knocking during acceleration. A regular spark plug replacement schedule is one of the simplest ways to reduce knocking in the engine.

3. Carbon Build-Up Inside the Engine

Fuel leaves behind carbon deposits over time. These deposits attach to pistons, valves, and the combustion chamber. Once they heat up, they act like small hot spots and ignite the fuel before the spark plug fires. That early burn leads to engine pinging and loss of power. A carbon clean engine service helps remove buildup and keeps the combustion cycle stable.

4. Incorrect Ignition Timing

Your engine depends on precise timing so the spark plug fires at the right moment. When the timing is too advanced, the spark fires early, forcing the piston down before it reaches the correct position. This creates a sharp knocking sound. A proper car tune-up can fix timing issues before they cause bigger damage.

5. Lean Air-Fuel Mixture

A lean mixture means there’s more air than fuel. This causes hotter combustion and makes the engine run rough. The high temperature inside the cylinder can cause knock, especially during acceleration. Faulty sensors, vacuum leaks, or weak fuel pumps often cause lean running. A check engine diagnostic at Biswas Automobiles can find the exact issue.

6. Cooling System Problems

Your cooling system controls engine temperature. If the coolant level is low or the radiator is clogged, the engine gets too hot. High heat increases the chance of early ignition and knocking. Watching the engine temperature gauge can help you catch this early. Our cooling system service checks coolant levels, hoses, and flow rates to keep the engine safe.

7. Worn Engine Bearings

Engine bearings help the crankshaft rotate smoothly. When bearings wear out, the crankshaft and piston rods lose support and begin to shift. This creates a heavy knocking or thudding sound. If this is not repaired quickly, the engine can fail. Worn bearings often require an engine repair, engine overhaul, or in severe cases, full engine replacement.

8. Faulty Knock Sensor

Modern cars have a knock sensor that monitors vibrations inside the engine. When it detects knock, it signals the computer to adjust timing and fuel delivery. If the knock sensor is faulty, the engine will not correct itself. This allows knocking to continue and may trigger the check engine light. A quick check engine diagnostic can confirm the sensor’s condition.

Can I Still Drive with Engine Knock?

You can — but you really shouldn’t.

Even light knocking means something’s wrong. Driving with engine knock can quickly turn a repair into a full engine replacement. It’s not worth the risk.

How to Stop and Prevent Engine Knocking

The best fix is prevention. Here’s what you can do:

• Use the Right Fuel:

  Don’t go cheap on fuel. Use what your owner’s manual says. For many modern cars, premium octane fuel is the best choice.

• Change Spark Plugs on Time:

  Regular spark plug replacement helps keep your ignition firing correctly. If you're unsure when they were last changed, ask your technician.

• Schedule Tune-Ups and Inspections:

  Routine car tune-ups catch timing issues early. This also includes checking timing belts, fuel injectors, and knock sensors.

• Clean Your Engine:

  Our carbon clean engine service removes built-up deposits that cause knock and restores fuel flow.

• Keep Your Engine Cool:

  Always check your coolant levels. Our cooling system service makes sure your engine stays at the right temperature.

When to Visit Biswas Automobiles

Don’t wait for your check engine light to blink. If you notice any signs of engine knock, come in right away.

Our team of trained engine repair experts will:

• Run a full engine diagnostic
• Check for faulty knock sensors
• Test air-fuel mixture and ignition timing
• Offer quick solutions, from spark plug replacement to engine overhaul

We handle everything from minor tune-ups to engine rebuilds — and we do it with honesty, precision, and the latest tools.

Why Choose Biswas Automobiles?

Since 2015, Biswas Automobiles has become one of Dhaka’s most trusted names for engine repair, check engine diagnostics, and car servicing.

• Hybrid and electric car experts
• Certified technicians with 9+ years of experience
• State-of-the-art German diagnostic equipment
• Home service and emergency towing available
• Trusted by car owners across Dhaka

Let’s Fix That Knock

Engine knock is not just noise — it’s a warning.

Come visit Biswas Automobiles at:

Let our team help you stop the knock and protect your engine — before it’s too late.

Frequently Asked Questions

What causes engine knock in cars?

It’s usually caused by poor fuel, bad spark plugs, timing issues, or overheating.

Can I drive if my check engine light is on?

If the engine light is on and you hear knocking, don’t drive. Visit a repair shop immediately.

How do I reduce knocking in my engine?

Use high-octane fuel, get a tune-up, clean your engine, and keep the cooling system in good shape.

How much does it cost to fix engine knocking?

Costs vary. It could be a simple spark plug issue or a need for engine replacement. We’ll run a full check and give you options.

Does Biswas Automobiles do engine replacement?

Yes, we offer complete engine repair, rebuild, and replacement services in Dhaka.

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