Caterpillar 3512B-SWAC Rebuild

Diesel Power Holland has successfully completed a full rebuild of a Caterpillar 3512B-SWAC for a European customer, carried out in our specialised workshop in Moerdijk, Netherlands. The 3512B-SWAC is a sea water after-cooled marine generator engine rated at 1,450 kW at 1,800 rpm — one of the most capable and widely deployed marine power units in the Caterpillar 3500 series. With decades of experience on 3512B variants across marine and industrial sectors, Diesel Power Holland is a trusted partner for complete CAT 3512B-SWAC rebuilds anywhere in the world.

What Is the Caterpillar 3512B-SWAC?

The Caterpillar 3512B-SWAC is a specific configuration of the CAT 3512B — a V12, 51.8-litre heavy-duty diesel engine — engineered specifically for marine generator set applications. The designation SWAC stands for Sea Water After Cooled, meaning sea water is used directly to cool the charge air in the aftercooler rather than routing through a separate freshwater cooling circuit. This design is highly effective on marine vessels where sea water is continuously available, reducing system complexity while maintaining superior thermal efficiency under sustained high-load operation.

The S2M engine prefix identifies this unit as a marine-rated generator set, built to the specifications required for classification society approval in commercial marine applications. Key technical specifications of this rebuild are:

• Configuration: V12 diesel, 51.8 litres
• Rating: 1,450 kW at 1,800 rpm
• Engine prefix: S2M
• Cooling system: Jacket water pump (engine cooling circuit) + sea water pump (charge air aftercooling)
• Engine management: Caterpillar ADEM III (Advanced Diesel Engine Management)
• Safety systems: Crankcase explosion relief valves (as required for marine classification)

What Does SWAC Mean on a Caterpillar 3512B?

The SWAC designation is a critical differentiator for marine operators selecting or rebuilding a 3512B. While standard industrial 3512B configurations use air-to-air aftercooling (ATAAC) or separate circuit aftercooling (SCAC), the SWAC variant draws sea water directly through the aftercooler heat exchanger. This allows the engine to maintain lower charge air temperatures — and therefore higher combustion efficiency and output — even in high ambient conditions typical of tropical and subtropical maritime operations.

The sea water cooling circuit operates in parallel with the freshwater jacket water circuit, each served by its own dedicated pump. This dual-circuit architecture requires specific expertise during rebuild and commissioning to ensure both circuits are correctly sealed, flow-balanced, and protected against corrosion — particularly the sea water side, which is exposed to saline environments.

Diesel Power Holland has the specialist knowledge and workshop equipment to correctly rebuild and test both cooling circuits as part of a complete 3512B-SWAC overhaul.

Caterpillar ADEM III: Engine Management on the 3512B-SWAC

The Caterpillar ADEM III (Advanced Diesel Engine Management III) is the electronic control module governing fuel injection timing, load response, speed regulation, and fault diagnostics on this engine. The ADEM III communicates with the vessel’s control systems and enables precise governor control, making the 3512B-SWAC suitable for demanding marine power generation applications where load acceptance and frequency stability are critical.

During the rebuild of this unit, the ADEM III system was verified and integrated with the fully overhauled mechanical components, ensuring seamless electronic-mechanical alignment on delivery.

Marine Safety: Crankcase Explosion Relief Valves

The 3512B-SWAC is fitted with crankcase explosion relief valves — a mandatory safety requirement for marine-classified engines operating in enclosed machinery spaces. These pressure-relief devices prevent the catastrophic failure associated with crankcase blowby ignition by venting excess pressure before it can build to dangerous levels. Their presence on this rebuild confirms that the engine is configured to full marine classification standards, as required by major classification societies including DNV, Bureau Veritas, Lloyd’s Register, and ABS.

Applications of the Caterpillar 3512B-SWAC

The CAT 3512B-SWAC at 1,450 kW is primarily used as a marine generator set engine on vessels requiring high-output auxiliary power. Typical applications include:

• Offshore supply vessels (OSVs) and platform support vessels (PSVs) — where continuous generator availability is essential for dynamic positioning and hotel load
• Dredgers and crane vessels — requiring sustained high electrical output for hydraulic and electric drive systems
• Ferries and RoPax vessels — where multiple generator sets share the vessel’s electrical load
• Offshore drilling units — as part of multi-generator configurations on semi-submersibles and jack-ups
• Large yachts and commercial passenger vessels — where reliability and classification compliance are non-negotiable

Why Choose Diesel Power Holland for Your CAT 3512B-SWAC Rebuild?

Marine operators worldwide choose Diesel Power Holland for 3512B-SWAC rebuilds because we combine deep Caterpillar technical knowledge with the logistical capability to serve vessels in any port. Our advantages include:

• Marine-specific expertise — we understand classification requirements, marine safety standards, and the specific demands of SWAC cooling systems
• Fast turnaround — with over 1,000,000 parts in stock, we can source critical 3512B components quickly, minimising vessel off-hire time
• Complete rebuild scope — from block inspection through to ADEM III verification and final system checks, we handle the entire process in-house
• Worldwide logistics — our yard in Moerdijk, Netherlands is ideally located for European and global shipping, with all required export documentation provided
• Experience since 1976 — nearly five decades of rebuilding Caterpillar 3500-series engines for marine customers across more than 100 countries

Request a Quote for a Caterpillar 3512B-SWAC Rebuild

If your vessel is equipped with a Caterpillar 3512B-SWAC and requires a complete rebuild, overhaul, or urgent spare parts — including sea water pumps, jacket water pumps, ADEM III control modules, crankcase relief valves, or internal engine components — contact Diesel Power Holland today. Our marine engine specialists will respond quickly with availability and lead times.

General enquiries: info@dieselpowerholland.com | +31 (0)168 388 488