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What is Rod Knock? Causes, Symptoms and How to Fix it

February 21, 2024 | Victor Lukasso

Rod Knock is typically caused by wear and tear on the connecting rods that hold the piston and crankshaft, leading to restricted movement.

Rod Knock is a significant issue in automotive, and its symptoms can sometimes be likened to other faults such as Detonation, Piston slap, Piston pin ticking, and Valve train ticking noises.

This has made many car users sell off their cars because if the Rod Knock isn’t addressed on time, it could further break, destroy or knock the car engine.

In this article, I’ll teach you what a Rod Knock is, the sounds, symptoms, prevention, and how to repair a vehicle that ran into a Rod Knock.


What Does a Rod Knock Sound like

One of the symptoms to expect if your vehicle runs into Rod Knock is the noise that comes with it.

This Rod Knock sound or noise results from one or more surfaces or connecting rods hitting or pinning against the crankshaft.

The pistons and crankshaft are joined by the connecting rods. And there is a bushing (often called roller-bearing) made of softer metal between the bearing rod and the crankshaft.

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Also, most engines are built with a precise and narrow tolerance that allows the caliper to fit in the crankshaft; this is made to allow motor oil to flow freely on the surface without resulting in wear and tear. However, as the engine ages, the metal caliper that joins the connecting rod begins to eat away, resulting in rod knock.

Symptoms of Rod Knock

Below are a few noticeable symptoms you’ll experience if you’re car runs into Rod Knock.

Knocking Sound:

As the name implies, you’ll continuously hear a loud sound like someone hitting a metal beneath your car. The noise will increase if you press the gas pedal.


Excess pressure on the bearing and piston will result in overheating.

Low Oil Viscosity:

When engine parts such as the crankshaft and its bearing start wearing out, the viscosity of the oil in the engine will decrease.

Causes of Rod Knock in Vehicles

Rod knocks are mainly caused by engine components’ wear and tear, which can be related to the low oil level.

As time goes by, the engine oil loses its viscosity, fluidity rating, and moisturizing characteristics as it passes through the engine. All of these cause internal corrosion and the accumulation of sludge in the engine, resulting in low oil pressure & improper oil circulation will occur if you drive your car with low oil levels.

This might cause severe engine damage and wear. Rod knocking may also result from other mechanical issues such as;

  1. Inadequate oil flow into the bearing surface
  2. Immoderate combustion pressure
  3. Faulty Flywheel
  4. Worn out Of the main bearing
  5. Over-revving the engines – High Poston inertia force
  6. Excess oil temperature
  7. Inadequate oil pressure
  8. Low oil viscosity & Pressure
  9. Bad alternator rotor bearings.
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To diagnose if the problem is a Rod Knock, you can diagnose your vehicle by checking the oil level on your car or performing an oil change.

How to Repair Rod Knock

A rod knock is just a warning that there is a problem with an engine’s internal components. This does not imply that your engine cannot be fixed.

However, you can tame the effect of rod knock and keep your engine stable before visiting an auto repair shop; some techniques are listed below.

1. Change the Oil and Oil Filter

Since rod knock is mainly caused by bad oil in the car engine, you might consider changing the oil with its oil filter to get rid of dirty oils permanently.

You can do this by unbolting the oil drain plug from beneath your vehicle.

Also, remove the old oil filter and replace it with a new one in case of Dirt and particles accumulate to decrease oil pressure and purity.

You can look up our article on changing Engine Oil for proper guidance.

2. Check the Connecting Rods

If the problem persists after an oil change, you might consider visually inspecting the connecting rods.

Also, check out for loose bolts and tighten them. You can also change the con rod.

3. Pour Fuel-Injector/ Carburetor Cleaner into your gas tank

Dirt particles get passage into your gas tank and then to the engine, which might eventually cause blockage.

Cleaning your fuel injector or carburetor ( for older vehicles) will eliminate particles in the fuel injection system and help curb rod knock.

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4. Use heavier oil or additive

5. Avoid oil levels dropping very low

6. Don’t allow coolant into your oil.

7. Replace the Rod bearing

Implementing one or all of the above fixes will stop or reduce the rate at which your vehicle runs into Rod Knock.


Is it worth fixing Rod Knock?

Yes, a rod knock is a signal that there’s a significant issue in your car engine and should be addressed immediately. Failure to address the issue might cause problems with other engine parts.

Can I still drive with a rod knock?

No, it isn’t advisable. Driving with a rod knock endangers your life and other road users.

You must park at a safe place and fix the problem if you don’t want further complications.

Does Adding oil solves Rod Knock?

It might solve the knocking Sound temporarily, which will return after some time. You must perform a total oil and oil filter change for maximum engine performance.

Can you hear the rod knock at idle?

Yes, Rod’s knock is audible during the engine’s startup, idling, acceleration, and deceleration. Stepping on the gas pedal will make the noise louder, and removing your leg will make it quieter. If anyone tells you otherwise, ignore them. Why? Rod knock is a loud banging sound that occurs when the engine first starts and lasts until the automobile is turned off.


One of those problematic engine issues that many people misunderstand, considering it to be the end of their car’s engine, is rod knock.

If you identify the symptoms head and act fast, your mechanic or dealership might be able to fix it without going over budget. However, if you see the warning signals mentioned above but ignore them, addressing the problems could be pretty expensive. Your engine replacement may be your only alternative at this stage.

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Meet Victor Lukasso, the owner of V. Auto Basics. Through this blog, Victor Provides Insights on the latest tips, maintenance, repair, and techniques in the automotive world.