On ocean voyages the two-stroke low-speed diesel engine is the heart that drives the ship forward. Its stability bears directly on the safety of the whole vessel, on fuel economy and on the efficiency of global supply chains. The cylinder liner, one of the engine's core components, works permanently under extreme conditions — high temperature, high pressure, strong corrosion and abrasive wear — and is prone to uneven wear, thermal distortion and even structural damage. Once liner condition gets out of hand, the mildest outcome is lost power and rising fuel consumption; at worst it leads to scuffing, a seized piston or even a crankcase explosion.
Regular, accurate and efficient in-situ measurement of liner bore has therefore become an indispensable part of modern preventive maintenance on board.
01. Clearance control: the lifeline of sealing performance
The running clearance between liner and piston rings is the basis of combustion sealing:
- Too little clearance: after thermal expansion the rings stick and no longer follow the liner wall, causing gas leakage and localised abnormal wear;
- Too much clearance: high-pressure combustion gas blows down and burns the lubricating oil, while oil passes upward and forms carbon deposits, accelerating wear on injectors and piston crowns and reducing power output.
Judgement based on experience or rough tools can no longer meet the accuracy requirements of today's highly rated engines. Only high-precision diameter measurement allows the actual clearance to be calculated properly and kept within tolerance.
02. Complex wear patterns require multi-dimensional identification
Wear in a two-stroke liner is highly non-uniform:
- Upper region: most heavily scoured by hot combustion gas, with significant corrosive wear;
- Top and bottom dead centre positions: ring reversal impact creates the characteristic step-shaped wear;
- Overall profile: roundness or cylindricity may fall outside tolerance, affecting sealing and lubrication.
CLDM (Cylinder Liner Diameter Measurement), developed by Dr. E. Horn of Germany for two-stroke engines with bores of 350 mm and above, supports multi-point self-centring measurement at different heights (upper, middle, lower) and in different directions (longitudinal and transverse), capturing wear, roundness and cylindricity deviations precisely to support repair decisions.
03. Breaking location constraints: immediate inspection in any port
Traditional measurement often requires removing the cylinder head and lifting out the piston — slow, labour-intensive and dependent on specialist engineers. CLDM needs no dismantling: the complete measurement is carried out through the scavenge port, which means:
- Immediate on-site inspection: whichever port the ship is in, the crew can work quickly inside the engine room;
- The whole process in-house: an intuitive interface and guided workflow let ordinary crew members work independently after brief training, greatly reducing dependence on external technical services;
- High fault tolerance: the system automatically detects operating deviations and prompts for correction, avoiding human error and keeping the data reliable.
04. Built-in calibration and industrial-grade protection for long-term stability
For the heat, oil and vibration of the engine room, CLDM uses a robust construction with no optical elements and no moving parts, rated IP65 for industrial protection, shock-resistant and corrosion-resistant, with long service life and low maintenance cost.
More importantly, its in-situ calibration technology lets users verify measurement accuracy at any time — with no return to a laboratory and no dependence on external standards — saving considerable time and logistics cost and keeping every measurement trustworthy.
Because two-stroke engines have no valves and rely on scavenge ports for gas exchange, CLDM can also measure liner dimensions in the scavenge port region, helping maintain gas exchange efficiency and combustion quality and further improving fuel economy.
The CLDM system combines low cost, high reliability, broad applicability and crew-friendly operation. It resolves the technical difficulties of monitoring liner condition on large-bore two-stroke engines and moves ship maintenance from reactive repair to active prediction. As the shipping industry pursues safety, efficiency and lower carbon, CLDM is becoming the intelligent sentinel guarding the health of the ship's heart.
We can propose a measurement package and application guidance tailored to your engine type and maintenance regime, and help you assess the return on investment and practical results. Contact Tecway for product documentation, case references and trial arrangements.
About Tecway
Tecway International Limited was founded in Hong Kong in 1993 and is a leading technical consultant and quality agent for the global maritime industry. Over more than three decades it has built five core business areas: marine equipment, petrochemical storage and transport, diesel and gas engines, marine technical services and maritime consultancy, serving markets across China, Southeast Asia, the Middle East and Europe.
Tecway is committed to the diesel and internal combustion engine sector, supplying products such as the Cylinder Liner Diameter Measurement system (CLDM) together with technical support. Our fast-response service network covers everything from sales consulting and installation through commissioning, training and after-sales service.
We also focus on the low-carbon transition of shipping companies, providing EU ETS and FuelEU compliance consulting, shipping green hydrogen project support, smart-ship dry-docking, export solutions for Chinese-made marine equipment and FGSS services.