How to Extend Life of An Engine With Rod Knock

A loud knocking sound coming from your engine every time you start up your car should be cause for concern. This sound is usually a pointer towards a problem with the connector rod bearings or the rods themselves. You can undertake various fixes to extend the life of your engine if it has a rod knock without having to replace the whole engine.

You can extend the life of an engine with rod knock, use high-octane fuel, change the engine oil, use high-quality oil, replace faulty plugs, replace the worn-out bearings, and keep the coolant at recommended levels. The permanent fix is by replacing the damaged connector and knocking rods.

What Is Rod Knock?

Rod knock refers to the loud noise the car’s engine produces when you rev it up and let off the gas. This deep sound is usually a sign of an engine issue.

Here is the sound of a rod knock:

What Causes Rod Knock?

The premature wear of the soft metal bushing between the crankshaft and the connecting rods causes rod knock. The metal bushing/bearing may wear out prematurely due to low oil pressure, engine overheating, low oil level, and use of dirty engine oil. Once the rod bearing wears down, there’s no barrier between the rotating crankshaft and the connecting rods, and the resultant friction as they rub against each other causes the loud noise known as rod knock.

Symptoms of Rod Knock?

As mentioned, the most surefire sign that your car has a rod knock is the loud knocking sound from the engine once you rev it and step on the gas. Another symptom of rod knock is low oil pressure. Oil pressure reduces when engine parts like bearings start to wear out. 

A common way to tell that your engine has low oil pressure due to rod knock is when the ‘check engine’ light and the ‘oil’ alert light up on your display board, then turn off once the engine has been running for a few minutes.

How To Extend the Life of an Engine With Rod Knock

Rod knock doesn’t necessarily mean that you have to invest in a new engine. You can extend the life of an engine with rod knock in the following ways:

• Replacing worn rod bearings
• Replacing damaged connector rods
• Avoiding overloading
• Replacing damaged spark plugs
• Using high-grade lubricants
• Checking the coolant level
• Replacing the piston rod

Replace worn bearings/metal bushing

Worn-out bearings hinder the optimal movement of the crankshaft and the pistons, resulting in rod knock. Therefore, you should inspect the rod bearings and replace them with new ones if worn out. 

Replace faulty connector rods

If the connector rods are damaged, replace them with new ones to fix the rod knock problem.

Avoid overloading

Exceeding the load limit can initiate engine rod knock issues or exacerbate the problem if it already exists. Therefore, you should avoid exceeding your car’s maximum weight capacity.

Replace damaged spark plugs

Connector rods and pistons are linked to the spark plugs. As a result, if the spark plugs are defective, they can cause damage to the connector rods, resulting in rod knock. To fix this problem, invest in replacement spark plugs.

Use premium-quality lubricants

Dry pistons can, at times, cause rod knock. Thus, you should always use high-quality lubricants like Valvoline vs. Castrol to keep the pistons well-oiled for smooth movement. 

Check the coolant level

The motor overheating can also cause a knocking noise from the engine due to low coolant levels. Therefore, if you hear this noise, check the coolant level and top it up if it’s too low. This will prevent the motor oil from thinning out and the engine overheating. 

Replace the piston rod

Defective piston parts can also cause rod knock. The pistons cause the crankshaft to rotate through their up-and-down movement. If the piston rods switch direction, rod knock occurs. If this is the case, you need to replace the piston rod.

How To Fix / Troubleshoot a Knocking Engine

To fix rod knock and stabilize your motor, consider the following:

• Do an oil change
• Tighten the connector rod caps
• Use a fuel injection cleaner

Do an oil change

An oil change can fix rod knock. Follow the steps below to undertake an oil change:

I. Position a catch pan below the drainage plug. Then, locate the crankcase drain plug

Ii. Use a socket and a wrench to loosen the crankcase drain plug and drain out the oil

Iii. After draining out all the oil, reinstall the crankcase drain plug in line with the manufacturer’s specifications

Iv. Using an oil filter wrench, twist the oil filter in a clockwise direction to remove it. Then, install a replacement filter and torque as per the manufacturer’s specifications.

V. Replace the engine oil. The oil should be of better quality or have the same viscosity.

Tip: Use well-recommended oils like Pennzoil, Valvoline, and Castrol

Check your connector rod bearing.

When one or more of the caps on the connector rods become loose, rod knock occurs. Therefore, you should check the bolts securing the con rod to the lid. If they’re loose, tighten them using a torque wrench.

Use a fuel injection cleaner

Dirt and grime can infiltrate your gas tank via the gas pump every time you refuel, resulting in rod knock. If you suspect this is the cause of your engine knocking, clean your fuel injection system to get rid of the dirt and reduce the knocking noise. However, avoid using fuel injection cleaner if you have an older carbureted car.

Tips To Prevent Rod Knock

Here are some tips on how to prevent engine rod knock:

• Always replenish your fuel tank at credible gas stations
• Always use gas with a higher octane rating if you can afford it. Alternatively, comply with the recommended minimum octane ratings in the owner’s manual.
• Regularly change your spark plugs as per the recommendations in the owner’s manual.
• Instantly lower the throttle anytime you hear engine knock sounds.
• Use a high-quality fuel additive to minimize carbon buildup.
• Get regular car tune-ups to identify and fix issues that may lead to engine knocks, like damaged plugs and clogged air filters.
• Keeping the coolant level at the recommended level can help prevent engine overheating and knocking.
• Regularly checking and changing the engine oil with high-quality brands like 5w30 synthetic can help reduce engine knock and prolong the engine life.

Here is a video guide on engine-knocking noise diagnoses and fixes:

FAQs

References

I. M.M Ismail et al: Engine knock detection for a multifuel engine using engine block vibration with statistical approach