Caterpillar 3508B locomotive engine rebuild

Diesel Power Holland completed a full Caterpillar 3508B locomotive engine rebuild to customer specifications, an 820 bkW unit at 1,500 RPM, serial prefix 5PS, arrangement number 135-1751. The engine was built as a clockwise rotation configuration and tested on the certified test bench of Pon Power prior to delivery. This project demonstrates the scope of Diesel Power Holland’s rebuild capability: from standard marine applications to purpose-built locomotive engines with specific rotation, accessory, and testing requirements.

Caterpillar 3508B Locomotive Engine: Project specifications

• Engine model: Caterpillar 3508B
• Application: Locomotive engine
• Output: 820 bkW @ 1,500 RPM
• Serial prefix: 5PS
• Arrangement number: 135-1751
• Rotation: Clockwise
• Build: To customer specifications
• Testing: Certified test bench — Pon Power

Delivered with:

• Electric starter
• Alternator
• Instrument panel
• Explosion relief valve
• Fuel cooler
• Fuel priming pump
• Original CAT parts throughout
• Full engine test

What is the Caterpillar 3508B?

The Caterpillar 3508B is a 34.5-litre, V8 diesel engine from the 3500 series — Caterpillar’s heavy-duty platform for high-power industrial, marine, and rail applications. The 3508B is the second-generation variant of the 3508, featuring mechanical fuel injection improvements and enhanced performance over the original 3508. It produces up to approximately 820–1,000 bkW depending on rating and configuration.

The 3500 series engines are built for continuous-duty, high-load operation and are commonly found in applications where reliability under sustained power demand is critical: large generator sets, marine propulsion, offshore drilling equipment, and — as in this project — locomotive drives.

The prefix 5PS identifies the specific serial number series of this 3508B, determining the correct parts specification, test procedures, and arrangement details for the rebuild. The arrangement number 135-1751 defines the exact accessory and component configuration as built.

Locomotive Engine Rebuild: What makes it different

Rebuilding a Caterpillar 3508B for a locomotive application involves requirements that differ from standard marine or industrial rebuilds:

Clockwise rotation: Engine rotation direction must match the driven equipment. Locomotive applications often specify clockwise (when viewed from the flywheel end) rotation as standard. This is determined at the assembly stage and cannot be changed in the field. Diesel Power Holland builds to the customer’s specified rotation.

Explosion relief valve: Locomotive engines typically operate in enclosed engine rooms or compartments where crankcase explosion risk must be managed. The explosion relief valve is a safety device that vents crankcase pressure in the event of an internal ignition event, preventing catastrophic failure. It is a mandatory component in many rail and enclosed industrial specifications.

Fuel cooler and fuel priming pump: Fuel management in locomotive applications requires dedicated cooling of the fuel supply (to prevent vapour lock under load) and a priming pump to ensure the fuel system is fully pressurised before startup, critical for a reliable cold-start sequence in operational conditions.

Test bench validation at Pon Power: This engine was tested at the certified Pon Power test facility, which operates independently from Diesel Power Holland’s own workshop. Third-party test bench validation provides the customer with documented, independently verified confirmation that the rebuilt engine meets its rated output, oil pressure, temperature, and mechanical performance specifications.

The rebuild process at Diesel Power Holland

A Caterpillar 3508B locomotive rebuild at Diesel Power Holland follows the same disciplined overhaul process applied to all 3500 series engines:

• Full disassembly of the V8 assembly — block, heads, crankshaft, pistons, and ancillaries
• Chemical cleaning and dimensional inspection of all components
• Replacement of bearings, seals, gaskets, pistons, liners, and valve train components using original CAT parts
• Assembly to customer-specified arrangement (135-1751) and rotation (clockwise)
• Installation of all specified ancillaries: electric starter, alternator, instrument panel, explosion relief valve, fuel cooler, and priming pump
• Independent performance and load test at Pon Power test bench

FAQ: Caterpillar 3508B Locomotive Engine Rebuild

What is the Caterpillar 3508B used for in locomotives? The 3508B is used as the prime mover in diesel-electric and diesel-hydraulic locomotives, as well as in rail maintenance vehicles and shunting locomotives. Its V8 configuration delivers high torque at relatively low RPM (1,500 RPM in this configuration), suited to the high-load, variable-speed demands of rail traction.

What does 820 bkW mean on the Caterpillar 3508B? 820 bkW is the brake kilowatt output — the net mechanical power delivered at the flywheel, measured under load on a test bench. This equates to approximately 1,099 HP and represents the rated continuous output for this specific 5PS/135-1751 configuration at 1,500 RPM.

Why is the 3508B running at 1,500 RPM instead of higher speeds? 1,500 RPM is the standard operating speed for 50 Hz generator drive and locomotive traction applications in Europe. It is a continuous-duty rating — the engine is designed to sustain full load at this speed throughout its service life. Higher RPM ratings exist for other 3508B configurations in different applications.

What is an explosion relief valve on a diesel engine? An explosion relief valve is a spring-loaded safety device mounted on the crankcase. If abnormal combustion or fuel ignition occurs within the crankcase, the valve opens to release the pressure surge, preventing the crankcase from rupturing. It is a standard requirement in enclosed locomotive and industrial engine specifications.

Can Diesel Power Holland build a 3508B to my specific rotation and arrangement? Yes. We build Caterpillar 3508B engines to customer specifications — including specific serial prefix, arrangement number, rotation direction, accessory package, and test requirements. Contact us with your specification to discuss your project.

Was this engine tested independently before delivery? Yes. This 3508B rebuild was tested at the certified Pon Power test bench, providing independently documented performance verification before shipment.

Need a Caterpillar 3508B Locomotive Engine Rebuilt?

Diesel Power Holland builds Caterpillar 3508B engines to your exact specification — rotation, arrangement, accessory package, and test standard. With over 1,000,000 original CAT parts in stock and 45+ years of Caterpillar rebuild experience, we deliver locomotive-grade reliability from our workshop in Moerdijk, the Netherlands.

Contact us to discuss your 3508B project requirements.