What Is Rod Knock? Symptoms, Causes, Diagnosis, and How to Fix

No one likes to face engine problems and strange sounds, which means repair and money. When you hear sounds from the engines, you may assume that it would be better to sell the vehicle than get it repaired.

But wait till you read this article as it may help you come up with some solution to repair it easily.  

What Are Rod Knock And its Symptoms And Causes?

Rod Knock is noise or sound caused by one or more connecting rods hitting or rubbing the crankshaft as it rotates in the cylinders. A very loud noise coming from the engine is one of the easiest symptoms to look for.

The sound occurs due to rod bearing damage. Car engines have many components, and after prolonged use, the rod bearing can wear out and have more slack allowing more piston movement.

As the piston moves from side to side, it can begin to strike the metal and produce knocking sounds. The sounds do not diminish even when the motion is accelerated while accelerating. The knocking sounds may increase when speed is increased and the gas is released.

Another symptom, along with dipstick knocking sounds, is low oil pressure. When the vehicle shows the engine oil light on and intermittently comes back on, the dipstick bearings may be worn, and you may also soon hear banging sounds.

Is Rod Knock a serious matter? 

Any strange sound coming from the engine means some damage to the car component. It is a sign of damage due to continuous use and something that you cannot ignore. 

This could be one of the signs that you must look out for and take a call on changing or repairing the bearings.

You Must Not Ignore The Rod Knock Sound

Sometimes it may not be easy to take the car for repairs or check the sounds coming from the engine. Ideally, though, you should not drive the car if you hear the sound to prevent further damage and complete failure.

While driving a car with a rod knock, the engine may suddenly fail, which will be an emergency for the car. The power steering may stop, and you may not be able to use the controls like the brake. 

The engine knocking sounds usually do not subside and may escalate to a continuous clatter with time erosion of the metal. The bearing will slowly erode, and the crankshaft and connecting rods will fall apart. That may lead to a hole in the engine block, and oil may spill on the hot exhaust. Some unfortunate people have reported engine fires too.   

Causes of Rod Knock

The most common reason is aging as the rod bearings age and wear out with use. Rod knock may most often happen due to bad or worn-out bearings, and their support to the piston is diminished. Pistons rotate the shaft and send power to the wheels, and if the bearings are worn out, then the piston’s movements are not even. 

Sooner or later, the bearings wear out completely, and the piston does not have any support left. The rod directly hits the crankshaft, and it is mandatory to repair or replace the rod bearings before they reach the stage.  

Fix That Rod Knock Before The Car Is Damaged Completely

The rod knock repair depends on many factors, and you must assess the following points.  

  • The damage in the engine rod bearings can be diagnosed.
  • The metal parts have eroded with time and constant knocking.
  • The knocking sounds have been around for some time, or you heard them recently.
  • The kind of engine and its components.

If the engine is in good condition, can it be repaired? 

Early detection followed by repairs is always the best option. You can repair the car easily by just changing the worn-out bearings. Professional mechanics can check the status easily after stripping down all the components. Depending on the damage, the engine can either be repaired or replaced. 

It Is Not Very Expensive To Fix The Rod Knock 

Repairing the rod bearings is not an isolated process as all the components are connected in an engine. Some of the other parts may need repairs if the rod knock is not repaired immediately.

The engine may need new seals, cylinder head bolts, gaskets, etc., apart from the rod bearing. Prolonged and ignored rod knocking may also force you to repair the piston and crankshaft. Some people do not understand the significance or postpone the repairs and then pay for an engine replacement.  

How Can You Fix The Rod Knock?

The process depends on the state of the engine and components. The engine may need to be rebuilt by replacing the bearings. The crankshaft needs to be inspected thoroughly as the loose rod’s movement may have damaged its surface. 

The crankshaft, in most cases, needs a coat of paint and turning around. If the crankshaft surface may show deeper marks, it may need to be turned around more, leading to breakage and replacement.

The bearings can be placed only after the crank is turned, depending on the place available for the rod bearings. A professional will check the rest of the components for signs of damage while repairing the rod bearings and change or repair the crank’s main bearings or the oil pump. 

It cannot be a DIY project as repairing, reconnecting, and replacing the rod bearing is not easy. The parts are located deep inside the engine. You must have the correct tools to open the parts and inspect and assess the damage before even starting repairing.

You will need new engine gaskets, seals, and the right cylinder head bolts while replacing the rod bearing. A professional will also service all the other parts and check for signs for damage in the piston, connecting links, and other bearings. It would be better to replace the entire engine if you have enough money than repeatedly replacing small components. 


Do not worry, and yet do not ignore the sounds coming from your engine. It could be some loose parts. But if you feel the sounds are getting louder, it is good to check the rod bearings. Repair and save your car in time from major expenses later.

Liam Dare

As CEO of ReplicarClub.com, my passion for the automotive world motivates me to build online businesses that provide information and entertainment to users. I am proud to contribute in a positive way to the automotive community.