What Causes Knocking Sound in Cummins Engine?

[LeBrandon]

Engine knocking sound may be caused by bending or twisting deformation of the engine connecting rod. The following are extended explanations: Other causes of engine knocking sound: Excessive carbon deposits in the engine leading to increased compression ratio and detonation; Poor engine lubrication conditions causing abnormal friction between pistons and cylinder walls; Incorrect gasoline grade usage resulting in excessive speed and high cylinder pressure, causing piston skirt to impact cylinder wall and produce knocking noise. Principle of engine knocking sound: Engine knocking sound refers to abnormal noise produced by impact against cylinder walls. The determining factor for piston knocking lies in the clearance between piston and cylinder wall. When piston clearance is too large, knocking is likely to occur. The noticeable manifestation is that when the car engine is cold, the piston clearance is large and knocking sound is louder. However, as engine temperature rises, piston clearance correspondingly decreases, and knocking sound will also diminish.

[DiAmara]

As an experienced auto mechanic, I've seen many cases of Cummins engines knocking. Generally, it's caused by fuel issues or mechanical looseness. Poor diesel quality or incorrect fuel grade can lead to incomplete combustion, causing detonation knocking that sounds like metal impact. Excessive clearance between pistons and cylinder walls can also cause this - severe wear over time may damage the engine core if continued. I recommend first checking if you're using compliant, genuine diesel fuel and replacing any substandard fuel. If the knocking persists, immediately consult a professional technician for diagnostic testing before serious damage occurs requiring major repairs. Regular maintenance is crucial - change engine oil and filters to ensure proper lubrication and reduce friction noise. Safety first - if you hear abnormal noises while driving, it's best to stop and inspect immediately.

[MariaLee]

After driving trucks for so many years, my own Cummins engine once experienced knocking sounds, which was caused by mixing poor-quality diesel with the fuel. It crackled during combustion and was especially noticeable at high speeds. Later, I switched to standard diesel at the gas station, and the noise reduced significantly. However, if it's due to loose piston pins or bearing wear, you might need to disassemble and check the gaps. Otherwise, long-term operation could shorten the engine's lifespan. Before every haul, I habitually check the oil level and lubrication to ensure the engine doesn't run dry. If you hear unusual noises, don't rush to hit the road—find an auto repair shop to pinpoint the exact location with a stethoscope tool. For prevention, I recommend servicing every 5,000 kilometers to avoid small issues turning into major problems. Spending a little now can save you from costly repairs later.

[LeLeilani]

As a car enthusiast, I think the knocking sound in Cummins engines is mostly due to unstable combustion. Using low-quality diesel in diesel engines can easily cause knocking, producing a sound like rhythmic pounding. Alternatively, loose mechanical components or increased clearance between pistons and cylinder liners can cause friction noises. A simple solution is to try switching to high-quality diesel while keeping the engine oil fresh to reduce wear. Maintenance is crucial, including regular cleaning of the fuel system. If the sound persists, seek professional inspection immediately—don't delay.