MTU Onsite Energy
Abnormal Combustion or Mechanical Knock
Loud knocking or metallic noise from engine under load
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Incorrect injection timing, Worn connecting rod bearings, Poor fuel quality, Loose flywheel or coupling
How to Fix / Troubleshooting
Safety first: Severe knocking can indicate imminent engine damage. Reduce load and shut down as soon as safely possible.
- Check fuel quality: Verify that fuel meets MTU specifications and is free of contamination.
- Listen for location: Use a mechanic’s stethoscope to localize the noise (top end vs. bottom end vs. flywheel area).
- Inspect coupling and flywheel: Check for loose bolts or damage at the flywheel and coupling.
- Professional diagnosis: Do not continue to operate with persistent knock. Contact an MTU service technician to inspect bearings and injection timing.
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Repair Difficulty
Professional Required
5/5
Required Part
Connecting Rod Bearings
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