Industrial engines are designed to handle challenging workloads in demanding environments. However, as these engines accumulate operational hours, the components inside may wear or become misaligned, causing abnormal noises. Environmental factors such as dirt, dust, temperature fluctuations, heavy load demands and maintenance can all contribute to the development of engine noises.
Even the most robust industrial engines, like those from Rehlko (Kohler) Engines, can develop unexpected noises over time. Whether operating in a mine site, powering construction machinery, or keeping agricultural equipment moving, strange engine noises should never be ignored.
The key to preventing significant issues is recognising engine sounds early. A sharp ear and understanding of common noises can save time, money, and ensure the engine continues to perform optimally. Here’s a breakdown of the most common engine noises and their possible causes.
Common Kohler Engine Noises and What They Mean
Knocking or Banging Noise – Conrod or Main Bearing Wear
Audible observation: A deep, rhythmic knocking or banging sound, often increasing with engine revolutions per minute (RPM).
Potential causes: This noise may indicate that a connecting rod or main bearing is worn or damaged. This type of sound is common in diesel and heavy-duty engines, especially those running under heavy loads.
Recommendation action: Stop the engine immediately if you hear a knocking or banging noise. Continuing operation can damage critical components further. The issue may require a bearing replacement or a complete engine inspection by a professional.
Ticking or Tapping Noise - Valve Train or Injector Issues
Audible observation: A rapid ticking or tapping sound originating from the engine’s top end.
Potential causes: tapping or ticking can be a sign of valve train problems, including incorrect valve clearance or a malfunctioning injector. This sound may also appear if there’s insufficient lubrication or worn valve components.
Diagnostic procedure: Start by checking the oil level and condition. If the oil is low or dirty, an oil and filter change may resolve the issue. More advanced diagnostics, such as valve lash adjustments or injector testing, may be necessary if the noise persists.
Recommended action: If the noise continues after changing the oil and filter, a qualified technician should conduct a thorough inspection of the valve train components.
Squealing Noise – Belt or Pulley Malfunctions
Audible observation: A high-pitched squealing or screeching noise, usually during engine start-up or acceleration.
Potential causes: This sound is commonly associated with worn or glazed drive belts or a malfunctioning tensioner.
Diagnostic procedure: Inspect the belt visually for signs of cracking, glazing, or wear. Ensure that the belt tension is correct. If the belt is old or damaged, replacing it should solve the issue.
Recommended action: Replace the belt if needed, and check the tensioning system. If the problem persists, inspect the associated pulleys for wear or misalignment.
Hissing Noise – Air or Exhaust Leaks
Audible observation: A hissing sound, sometimes coupled with a reduction in power or performance.
Potential causes: This sound is often caused by an air or exhaust leak, commonly occurring in turbochargers, boost lines, or exhaust manifolds. Air leaks can reduce engine efficiency, while exhaust leaks can affect emissions and power output.
Diagnostic procedure: perform a visual inspection for any cracks, loose connections, or missing seals around the turbocharger, exhaust system, or boost lines. Use a smoke test or listen closely around joints to detect any air escaping.
Recommended action: Replace or repair any damaged components, such as cracked pipes, blown gaskets, faulty seals, or loose connections.
Advanced Warning Signs in Industrial Settings
Grinding Noise – Water Pump, Alternator, or Bearing Failure
Audible observation: A grinding or whining noise, especially when the engine is under load.
Potential causes: A grinding sound can indicate that the water pump, alternator, or one of the engine’s bearings is failing. When these critical components malfunction, they can cause significant engine damage if left unchecked.
Recommended action: turn off the engine and inspect the water pump and alternator for wear and bearing play, and check for any leaks. If necessary, replace the bearings or the failing components before further damage occurs.
Rattling Noise – Loose Components or DPF Problems
Audible observation: A rattling or metallic sound, particularly under load.
Potential cause: Rattling can be caused by loose engine components or problems with the Diesel Particulate Filter (DPF) in diesel-powered engines. Over time, DPFs can become clogged or damaged, leading to unusual noises during operation.
Recommended action: Check for loose engine mounts, bolts, or shields. If the noise is related to the DPF, it may require a “burn-out” or “regeneration”, repair or replacement.
Whining Noise – Hydraulic or Fuel System Concerns
Audible observation: A continuous whining noise, especially under load.
Potential cause: A whining sound is often linked to hydraulic or fuel system problems, such as pump wear or fuel system cavitation. This could result in improper fuel pressure or inefficient hydraulic operation.
Diagnostic procedure: Check hydraulic fluid levels and fuel system pressures. Verify if any of the system components are clogged or malfunctioning.
Recommended action: Replace any worn hydraulic pumps or fuel system components and flush the system if necessary. Also, filters should be replaced regularly.
Troubleshooting Tips for Site Technicians
Using Diagnostic Tools and Engine Monitoring Systems
Modern industrial engines come equipped with onboard diagnostic systems that help monitor engine performance and alert operators to potential issues. Use the engine manufacturer’s diagnostic software and tools to check for error codes or irregular system readings. These tools can give you more detailed insights into what’s happening inside your engine, and will save a lot of time when troubleshooting. The Rehlko/Kohler “KIRA” (Kohler Integrated Remote Assistance) Diagnostic System not only pinpoints the possible trouble spot, but also guides on how to rectify the problem. Furthermore, the KIRA Diagnostic System is also required for certain regular maintenance procedures, such as DPF Regeneration to avoid “limp mode” conditions. Join our network of KIRA experts, with free training available from EPG Engines. Contact us for more information.
Visual and Audible Checks
Sometimes, a visual inspection can help you spot the source of an unusual engine noise. Check all engine components, hoses, belts, and filters for visible wear and tear. Use a stethoscope or listening devices to pinpoint the exact source of the noise.
When to Stop Operation Immediately
Some engine noises signal that your engine is in danger of serious damage. If you hear loud knocking, grinding, or any unusual sounds combined with smoke, power loss, or temperature issues, it’s critical to stop the engine and conduct a thorough inspection. Continuing to operate the engine in these conditions can lead to further damage and costly repairs.
Trust the Experts – Rehlko/Kohler Engines Powered by EPG
Every noise your Kohler engine makes is a message, and understanding those sounds can save you from major repairs and downtime. Whether it’s a knock, tick, squeal, or hiss, use this guide to identify the problem early. And if you're unsure, reach out to EPG Engines, your go-to network for reliable service and nationwide support as a sole Australian distributor for Rehlko/Kohler Engines since 1980. Don’t wait until a small issue becomes a major headache - contact us today for expert help.