Understanding Abnormal Noises in Loader Forklift Diesel Engines and Their Causes

A loader forklift diesel engine in good condition produces a uniform and slight exhaust sound at idle and a steady roar at high speeds. However, when abnormal noises occur, it is essential to identify the specific sound, working conditions, and potential causes. In this article, we will explore common abnormal noises found in loader forklift diesel engines and discuss their possible causes. By understanding these issues, you can diagnose and address them promptly, ensuring optimal performance and preventing further damage.

1. Valve Knocking Sound: Symptoms: A crisp metal knocking sound on the cylinder head cover, especially noticeable during shifting at medium and low speeds. Cause: Excessive valve clearance due to loose valve adjustment screws or wear in valve mechanism components (cams, tappets, rocker arms, etc.). Action: Adjust the valve clearance as recommended to restore proper functioning, prevent power loss, and reduce fuel consumption.

2. Piston Pin Ringing: Symptoms: Pronounced ringing sound during acceleration from idle to medium speed, with the frequency changing as engine speed rises and falls. Cause: Excessive fit clearance between the piston pin, connecting rod bushing, or piston pin seat hole. Action: Disassemble and inspect the piston pin, connecting rod bushing, and piston pin seat hole. Reassemble or replace components as necessary to eliminate the noise.

3. Piston Knocking on the Cylinder: Symptoms: A distinct "dang" sound caused by piston swing resulting from excessive wear between the piston and cylinder wall. Cause: Worn piston or cylinder wall, leading to excessive fit clearance. Bent or deformed connecting rods can also cause this noise. Action: Identify the cause of the knocking sound and take appropriate action, such as repairing or replacing worn components.

4. Connecting Rod Bearing Ringing: Symptoms: Audible noise at medium speeds, increasing as the speed rises. The noise may diminish or disappear at idle. Cause: Wear in the journal and bearing, bearing alloy layer burnout or detachment, loose bearing cover, or bearing rotation. Action: Inspect the connecting rod bearing, repair or replace worn components, and ensure proper lubrication to prevent further damage.

5. Crankshaft Bearing Noise: Symptoms: Clear noise during sudden acceleration or deceleration, accompanied by engine vibrations during heavy-duty operation. Cause: Similar to connecting rod bearings, worn or damaged crankshaft bearings result in noise. Action: Check the bearings for wear or damage, repair or replace them as needed, and maintain proper oil pressure and lubrication.

6. Camshaft Bearing Noise: Symptoms: Intermittent, rhythmic blunt clicking sounds at medium speeds, noticeable even at idle. Cause: Wear between the camshaft and bearings, excessive fit clearance, or bearing alloy layer burnout or detachment. Action: Inspect the camshaft and bearings, replace worn components, and ensure proper lubrication for optimal performance.

Conclusion: Abnormal noises in loader forklift diesel engines indicate underlying issues that require attention. By understanding the specific noises, their associated causes, and taking appropriate action, you can effectively diagnose and resolve these problems. Regular maintenance, including checking fit clearances and ensuring proper lubrication, is crucial for preventing excessive wear and damage. Promptly addressing abnormal noises will enhance the longevity and reliability of your loader forklift's engine, ensuring its optimal performance. Remember, when in doubt or facing complex issues, consult a professional technician for further assistance.