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Technical Article
Marine Diesel Engine Low Compression: Causes and Diagnosis
Low compression pressure is commonly caused by worn or broken piston rings, cylinder liner wear, exhaust valve leakage, cylinder cover sealing problems, damaged piston crown, or incorrect valve timing. Diagnosis should combine compression readings with visual inspection and component measurements.
Symptom, possible cause and inspection
| Symptom | Possible cause | Inspection |
|---|---|---|
| Low compression on one unit | Ring/liner wear, exhaust valve leakage, or cover sealing issue | Inspect ring pack, liner, exhaust valve, and sealing surfaces |
| Slow pressure recovery after overhaul | Running-in issue or incorrect assembly | Review assembly records and inspect affected components |
| Low power and smoke | Poor compression plus fuel issue | Check compression, injector condition, and combustion data |
Measurements and acceptance limits
Condition assessment should be based on recorded measurements, visual findings, operating symptoms, and the applicable maker documentation. Acceptable limits should be confirmed against the applicable manufacturer's manual and engine-specific technical documentation.
Need technical assistance?
If inspection, overhaul, troubleshooting, workshop repair, or onboard attendance is required, Dieselmech Group can review the symptoms, engine details, operating history, and available measurements before recommending the next practical step. Contact us at +65 6334 1855, email sales@dieselmech.com.sg, or submit an enquiry through the Contact Us page.
Technical note
This article is for general technical information. Actual procedures, limits, clearances, pressures, temperatures, torque values, and renewal criteria depend on the engine model, configuration, maker revision, service bulletin, vessel procedures, and class requirements. Manufacturer manuals and vessel safety procedures take precedence. Safety-critical work should be carried out by appropriately qualified personnel.
Published by Dieselmech Group Technical Team. For advice on a specific engine or fault, contact our marine engineers.
