The MAN B&W L23/30H engine series was launched in 1965, under the Holeby engine program before later becoming part of the MAN B&W. The engine was designed to meet the growing demand for a compact, fuel-efficient, and highly reliable medium-speed diesel engine for marine auxiliary and propulsion applications. The L23/30H engine became known as the “workhorse engine” of MAN B&W and established itself as one of MAN B&W’s most successful four-stroke marine engines, with more than 12,000 genset units produced by 2021. The L23/30H engines are extremely popular as auxiliary generating engines onboard cargo ships, tankers, bulk carriers, offshore support vessels, ferries, fishing vessels, and naval ships. The L23/30H engine delivers power outputs between 720 kW to over 3,000 kW, at speeds from 720 and 900 rpm. One of the major reasons behind the success of the L23/30H engine series was its robust and modular design, which allowed for simplified maintenance. Key features included a rigid cast-iron engine block, efficient turbocharging with intercooling, optimized fuel injection systems, and the capability to operate on MDO and HFO. The engine also became known for its smooth load response, low fuel consumption, long overhaul intervals, and excellent reliability. Over the years, the MAN B&W L23/30H underwent several important upgrades. Later variants such as the L23/30H Mk2 introduced higher power density, improved combustion efficiency, strengthened pistons and connecting rods, upgraded turbocharging, and lower specific fuel consumption. More recent developments such as the L23/30H Mk3 further improved emissions performance, fuel efficiency, operational flexibility, and digital monitoring capabilities to comply with evolving IMO regulations. These continuous upgrades have allowed the L23/30H engine to remain commercially competitive and operationally relevant even now. 

Although many earlier MAN B&W L23/30H engines are now considered legacy units, they continue to remain widely used across global fleets due to their proven reliability and strong aftermarket support. Support remains readily available through MAN licensees, specialists and second-hand engine parts suppliers such as Alang Maritime. With access to original unused surplus components sourced from decommissioned vessels, a large inventory of stock accumulated over decades, and reliable sourcing through trusted local traders, Alang Maritime has become a strong supplier for MAN B&W L23/30H engine parts to some of the world’s biggest ship management companies.  

Engine Configurations: 5L23/30H, 6L23/30H, 7L23/30H, 8L23/30H, 9L23/30H

Supply scope of Alang Maritime for MAN B&W L23/30H engines:

Complete engines, crankshafts, cylinder heads, cylinder liners, pistons, connecting rods, engine blocks, exhaust valves, inlet valves, valve seats, bearings, lube oil pumps, air starters, fuel injectors, plungers and other consumables.

Alang Maritime is one of Southeast Asia’s premier suppliers of high quality second hand spare parts for two-stroke and four-stroke marine diesel engines. We can supply new (unused surplus) parts that are obtained from scrap vessels or shipowners’ surplus from cancelled projects. We can also supply reconditioned parts, as well as used parts that are offered with technical reports.

The brands that we supply parts for are:

Yanmar | Daihatsu | MaK | Wärtsilä | MAN B&W | Bergen | Sulzer | Pielstick | Caterpillar | Niigata | Hyundai-HiMSEN

Alang Maritime stocks new, reconditioned, as well as quality controlled used parts for marine diesel engines. Our strengths are our 30+ years of experience in the maritime industry, a huge stocking space of more than 3,500 sq. mt., an extensive stock of more than 25,000+ engine parts, our technical knowledge of marine diesel engines and our close proximity to the Indian ship recycling yard of Alang. That is why Alang Maritime is your premier solution for high quality marine diesel engine parts at an economical cost.