What is Rod Knock? Symptoms, Causes, Diagnosis, and Fixes for 2024

Most people dread having to deal with engine issues and maintenance. Wouldn’t you? It is common for a motorist to consider trading or selling their car when they begin encountering engine issues, believing the repairs would be pricey.

You may consider trading or selling your car if you notice a rattling noise coming from the engine. Fortunately, there are a number of engine issues that may be easily remedied.

This article will explain what is rod knock, its symptoms, diagnosis, and the best way to treat it. How to avoid rod knocks will be covered in great depth in this section. Defining the rod knock will help us understand the rest of this discussion.

What does rod knock mean?

What does rod knock mean

Any noise or sound produced when a connecting rod rubs against the shaft as it turns in the cylinders is known as “rod knock.” The pistons and crankshaft are attached to the connecting rods. In addition, a bushing (often referred to as a bearing) composed of softer metals than the crank and con rod sits between them.

To ensure the bushing fits snugly in the crankcase journal, automobile engines are built with a clearance tolerance. Because of the little clearance, engine oil is able to flow over the metal surface without causing damage. In the long run, though, the convention rod and crank metal bushing will wear out, causing the rod to shimmy and vibrate.

Because it requires lots of bushing to degrade, rod bangs aren’t generally the result of natural wear and tear. Premature wear is the most common cause of rod knocks. Premature wear may be caused by a variety of factors. There are a number of possible causes for this, including filthy oil, poor hydraulic systems, and engine overheating.

What is Spun Bearing?

What is Spun Bearing

It’s not uncommon for engine cylinder bores to be spun, and this is what the term “spun bearing” means. In other words, what am I trying to say here? Spindle bearings are formed when lubrication is lacking, and the crankshaft is unable to revolve freely inside a bearing housing.

During an engine rebuild, poor bolt torturing may strain connecting rods or nuts, resulting in this problem. Other variables, such as the absence of grease, extreme heat, and system administrators’ loads, might cause the gear to wear out. It is possible for a spinning bearing to be caused by other sources.

Symptoms of rod knock

Symptoms of rod knock

If you notice a rod knock, there are a number of telltale signs to look out for in your car. The following are the symptoms of these conditions:

Knocking sound: A pounding sound is the most prevalent sign of rod knock. The sound of slamming or knocking (as if someone were striking metal against your iron door) may be heard when you start your automobile with a rod knock installed. As you press down on the gas pedal, the engine’s noise level will rise.

Low oil pressure: Engine oil pressure decreases when worn-out parts such as the flywheel, camshaft, and bearings begin to show. When you initially get in the automobile, you’ll see this more clearly.

The check engine and oil light may come on in certain circumstances, suggesting that there is a problem with the fuel pump. A rod knock is indicated if the lights go out driving and the pressure returns.

What causes rod knock

What causes rod knock

Corrosion to the engine’s internal components is the most common source of rod knocks. What may have caused the internal engine components to wear out? Low oil pressure and infrequent oil changes are the most common culprits.

The density, viscosity, and lubricating characteristics of motor oil degrade with time as it travels through the engine. All of these factors contribute to engine sludge and corrosion.

Driving a vehicle with little oil may cause low oil pressure, which will cause the oil to not circulate properly. Engine wear and failure might occur as a consequence of this. Rod banging may be caused by a variety of mechanical issues. Among them are:

  • The timing chain tensioner may be defective or loose.
  • Weakness in the primary bearing
  • A rusted water pump bearing is to blame.
  • Flywheel or flex-plate damage
  • Damaged rotor bearings on the alternator

How to Diagnose rod knock

How to Diagnose rod knock

Check the state of the oil and oil level

To determine the condition of the oil, you must first check the level and then remove a sample to observe the color. Dirty motor oil has a muddy or black appearance. Check your oil level and condition by reinstalling your dipstick and pulling it out in order to re-inspect it. Component wear, breakage, and engine banging may result from dirty oil.

Drain the engine oil and inspect it

Keep an oil collecting pan nearby to prevent contaminating the whole garage. Check the oil viscosity on your engine cap before emptying it. This is critical so that you don’t replace the old grease with the incorrect kind of oil.

Get a clear jar to hold a cup of old oil so you may examine it more closely before draining it. The oil should be drained once the sample is removed for further scrutiny. Metal filings in the lubricating oils are a sign that the engine’s components have worn down. Metal shavings from the bearing rod, crank joint, or other engine components may be the source of the banging noise.

Aside from that, keep an eye on the oil’s hue. If the oil has a dark brown color, it’s unclean or old and should be swapped out right away. Consider changing the oil if it’s too thin. You may prolong the lifespan of an automobile with rod knock by following a few basic rules. Make sure you replace your oil on a regular basis.

How to fix a rod knock

How to fix a rod knock

A rod knock is a sure symptom that something is wrong with the engine’s internals. There are a variety of causes for rod knock, some of which need costly repairs while others do not. It’s not the end of the world if your engine can still be fixed.

There are, however, a few things you can do to decrease the rod knock and balance your engine before contacting your dealership or technician for a full repair.

Carry out oil change service

Using an oil filter wrench, spin the oil filter clockwise to remove it. Replace the filter and tighten it per the manufacturer’s recommendations. The oil viscosity grade or suggested oil should be used to replace the old one.

Remove the crankcase and inspect the cod rod bearing

Knocking noises may be heard if the connecting rod cover is unfastened. Re-torque the bolts that hold the con rod to the lid. Make sure to examine and replace any worn cod rod bearings that you find.

Pour fuel-injection cleaner into your gas tank

When you fill-up your gas tank at the gas station, dirt and grime may find their way into your tank, and engine banging is caused by dirt and grit being carried by the fuel pump as it delivers gas to the engine.


Can oil change stop engine knock?

A blood spattering, tickling, or ticking sound from the engine usually indicates insufficient oil pressure or a depleted oil supply. If the noise is coming from the valves or rockers, adding or changing the oil will solve the problem. An oil change, however, will not help with a rod knock.

Will thicker oil stop rod knock?

Rod knock may be reduced or eliminated by using a higher viscosity oil (heavier or thicker oil). In theory, it will extend the life of your engine. This does not imply that you should not investigate and remedy the problem.

How long will an engine last with rod knock?

Some people wonder, “how long can I drive with a rod knock?” if they have a rod knock in their car, It is impossible to predict how long a vehicle’s engine will endure once it begins to squeal.

As soon as you start your car again, you might have a complete breakdown, or it can continue to run for three to six months. A few minutes of driving while the rod is vibrating is not suggested. If your engine fails, you’ll be stranded in the center of nowhere.

Can you hear rod knock at idle?

When the engine is started, idling, accelerating, or decelerating, you can definitely hear the rod knock. When you stomp on the gas pedal, the noise level will rise, and when you take your foot off the pedal, it will fall. Anyone who tells you differently should be ignored. Why? During the engine beginning, you may hear a loud pounding noise called “rod knock.” This noise will remain until you switch off the automobile and turn off the ignition.

What happens when you hear a rod knocking?

The engine parts moving elements are causing rod banging. Knocking or banging noises, low oil resistance, and an engine light in the instrument cluster are all signs that something is wrong with your vehicle. If you don’t find out what’s wrong and repair it in time, the engine will be severely damaged.


Rod knock is without a doubt one of the most debilitating auto issues. The challenge, however, is often referred to as an insurmountable one. Since automobile owners hear banging noises, they quickly conclude that the vehicle they are driving is likely to go out.

You’ll need to be able to recognize the issue and fix it before you can fix it. Take a look at some of the simple adjustments we’ve already mentioned. It has the potential to be the answer. A mechanic will be needed if you can’t determine the cause of the banging sound.

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