Caterpillar Marine
Spare Parts Supplier
CAT 3500 · 3600 · C32 · C18 · MaK
Caterpillar marine engine models covered
Spare parts RFQs may reference CAT 3500-series, 3600-series and C-series marine engine configurations. Exact model, serial/build evidence and installed application are checked before a route is confirmed.
CAT 3508
8-cylinder V-form diesel, auxiliary and propulsion. Cylinder liner sets, piston assemblies, injector tips, turbocharger cartridges, gasket kits.
CAT 3512
CAT 3512 RFQs can include piston rings, cylinder head gaskets, injector assemblies, water pump seals and valve sets. Confirm the complete engine identity and arrangement.
CAT 3516
16-cylinder high-output diesel for main propulsion and gensets. Connecting rod assemblies, bearing shells, fuel injection components and turbocharger nozzle rings. Review the dedicated CAT 3516 marine spare parts route.
CAT 3606 · 3608
Large-bore medium-speed main propulsion engines. Cylinder heads, piston crowns, exhaust valve assemblies, camshaft components, crankshaft bearing shells.
CAT 3612 · 3616
High-power V-form main engines for large vessels. Fuel injection pumps, cylinder liner kits, charge air cooler elements, governor components, overhaul seal sets.
CAT C32
High-speed V12 marine diesel, built as a propulsion engine and as a generating set. Injectors, turbocharger units, piston ring sets, water pump assemblies, heat exchanger elements.
CAT C18
Compact in-line six-cylinder diesel for auxiliary and propulsion. Cylinder head kits, injector assemblies, timing components, cooling circuit seals, gasket sets.
MaK M 20 · M 25 · M 32
MaK medium-speed engines, built in Kiel under Krupp ownership until 1997 and by Caterpillar Motoren after that; Caterpillar Motoren also built them in Rostock, where the last engine left the plant in March 2023. Cylinder heads, liners, fuel injection equipment, turbocharger components and overhaul gasket kits — reviewed against the engine evidence supplied with the RFQ.
What a MaK marine diesel looks like in service
Reference photography of a Caterpillar-built MaK marine engine — useful for confirming engine family and reading nameplate data before an RFQ is submitted.
Representative licensed photography, not a Vessel Core installed reference or completed job. Engine and nameplate photos: Eduard47, Wikimedia Commons, CC BY-SA 4.0. Vessel Core has no dealership, distribution or partnership agreement with Caterpillar Inc. or Caterpillar Motoren GmbH & Co. KG; it operates as an independent spare parts supplier.
Cat and MaK: one owner, two engine programmes
Two quite different ranges reach an engine room under this ownership. The Cat-branded programme — the 3500 and 3600 families, the C-series and their generating-set derivatives — is high-speed and medium-speed machinery of Caterpillar design. The MaK programme is something else: Maschinenbau Kiel built medium-speed engines in Kiel long before Caterpillar bought the MaK marine engine business from the Krupp group in 1997, and the company now trades as Caterpillar Motoren GmbH & Co. KG, the name on the nameplate pictured above. The M-series engines kept their own designations, their own parts documentation and their own service tradition, and a plate reading MaK is not read the way a plate reading Cat is.
There is a second thing worth knowing before an M-series enquiry is written. In 2021 Caterpillar decided to stop building large engines at Caterpillar Motoren, the home of the MaK range, and the last new engine left its Rostock plant on 30 March 2023. The engines themselves did not go anywhere: a large installed fleet is still running, and aftermarket support for it — maintenance, overhauls and original spare parts — continues through the service network. What changed is the context an owner is buying in, and that is a reason to identify an M-series engine carefully rather than a reason to worry about it.
For a buyer the practical consequence is simple. A request that says only Caterpillar can mean either programme, and the two do not share catalogues. Saying which plate the line came off — a Cat model number or a MaK M-series designation — is the first thing that narrows it, and it costs nothing to say.
CAT marine spare parts supply scope
Planned maintenance items, overhaul kits, and time-critical spare parts for Caterpillar marine engines — organised by system and component group for efficient RFQ processing.
- Cylinder liners & liner O-ring sets
- Piston assemblies & piston rings
- Cylinder head assemblies & gaskets
- Exhaust valves, guides & seat inserts
- Fuel injector assemblies & nozzle tips
- Injection pump plungers & barrels
- Turbocharger cartridges & housings
- Main bearing shells & thrust washers
- Connecting rod bolts & bearing shells
- Water pump impellers & mechanical seals
- Lube oil pump gears & relief valves
- Heat exchanger & charge air cooler elements
- Governors & electronic control components
- Full overhaul gasket & seal kits
Serial prefix and arrangement number: the two figures CAT works from
Caterpillar identifies an engine with a system of its own, and knowing how it reads saves most of the questions an enquiry would otherwise generate. The serial number begins with a three-character prefix followed by a sequence. The prefix belongs to a build family and a plant, and a single model can have been produced under several prefixes over its life, so the prefix narrows the engine in a way the model number cannot. Next to it sits the arrangement number, which identifies the specific configuration the engine was built and shipped as. Parts research on this maker is done against the serial number and the arrangement number together; the model designation is where it starts, not where it ends.
- Full model as stamped, with any generation letter — 3512C, C32, M 32 C
- Serial number complete with its three-character prefix, photographed rather than transcribed
- Arrangement number from the same plate — the single most useful figure on a Caterpillar request
- Whether the plate reads Cat or MaK, since the two programmes are documented separately
- Rating letter where the plate carries one, because it changes what was fitted on the fuel and cooling side
- Duty: propulsion, auxiliary generating set or harbour set, and the reduction gear make where it drives a shaft
- Bank and cylinder number for any running-gear line on a V engine
- Injection described as unit injectors or as pumps and nozzles, since the generations differ on this
- Turbocharger make and designation from its own plate, and how many are fitted
- Old part number and the parts-book page it came from, treated as a starting point rather than a conclusion
- Bearing shells with the undersize stated, and ring sets quoted per cylinder rather than per ring
- Control module part number where the line touches the electronics
- Running hours since the last top overhaul and since the last full overhaul, given separately
- Photographs of the engine plate and of the component in place
Tools for this equipment: the Pt100 and thermocouple reader for the temperature sensors, the pressure gauge selector for the engine gauges and the O-ring size finder for loose O-rings. The fuel consumption calculator works out the fuel use of a propulsion engine or a generating set from its SFOC and power. Where the engine has a charge air cooler, the charge air condensate calculator estimates the water that drops out of the charge air after it.
OEM-route and verified alternative review for CAT marine parts.
Caterpillar Marine equipment may require OEM-route review, verified alternative review or both depending on lead time, documentation and approval context. Vessel Core structures the RFQ according to buyer approval needs and vessel timing.
OEM or Alternative — You Decide
OEM-route parts can be reviewed for class-critical or warranty-covered work. Verified alternative components can be reviewed for wear items and running spares, with documentation requirements checked at RFQ stage.
Lead Time Confirmed at RFQ Stage
We put a date against a CAT line only once a supplier has committed to it: 3500-series running spares and 3600-series large-bore components rarely move on the same clock, so we quote them line by line rather than as one order.
Route and Budget Review
Verified alternative supply routes for CAT wear items — piston rings, liner sets, injectors and gasket kits — can be reviewed where buyer approval allows it. Pricing, lead time and documentation notes are provided at RFQ stage.
Time-Critical CAT RFQ Review
Breakdown situations for CAT main engines can be marked for priority RFQ route review. A time-critical RFQ flag starts availability review, route comparison and freight option checks based on vessel timing and port timing.
Technical Part Identification
Without a part number, a CAT line can still be identified from the serial number with its three-character prefix, the arrangement number or a component description. Model plate photos and drawings are also accepted as identification input.
Port-Aware Delivery
Delivery options are reviewed against your vessel's port schedule and ETA. CAT spare parts can be quoted with port-aware handover options when routing and availability are confirmed.
CAT marine parts — common questions
Can you review verified alternative routes for CAT 3500 and 3600 series marine engines?
Yes. We review OEM-route and verified alternative routes for CAT 3500 and 3600 series marine engine requests. Alternative routes for wear items such as piston rings, liner sets, injector assemblies and gasket kits are reviewed case by case against approval needs, documentation and vessel timing.
What Caterpillar marine engine models do you cover?
Vessel Core can quote and review common CAT marine engine spare parts RFQs used in commercial shipping, including 3500 series, 3600 series, C-series and MaK medium-speed requests where the buyer can provide clear engine and part evidence. MaK engines were built in Kiel, under Krupp ownership until 1997 and by Caterpillar Motoren afterwards, so a MaK plate is Caterpillar in the corporate sense and MaK and Cat-branded requests are handled on the same desk. Propulsion and auxiliary generator set configurations can both be reviewed.
How do you handle time-critical CAT engine parts requests?
When a request for a Caterpillar engine is marked time-critical, supplier availability, possible alternative routes and freight options for the vessel's current or next port are checked first. Lead time is confirmed only in the quotation.
Can you supply CAT marine injector assemblies and fuel system parts?
Yes. Fuel injector assemblies, injector tips, injection pump components, and high-pressure fuel lines for CAT 3500 and 3600 series engines can be reviewed through structured RFQ evidence. OEM-route and verified alternative injector supply routes can be reviewed case by case. Part numbers, engine serial numbers, and arrangement numbers all accelerate the quoting process.
My plate reads MaK. Is that a Caterpillar engine, and is it still supported?
It is Caterpillar in the corporate sense and a separate programme in the parts sense. Caterpillar bought the MaK engine business from the Krupp group in 1997, and the M-series engines kept their own designations and parts documentation. Caterpillar announced in 2021 that it would stop selling new MaK prime-product engines by the end of 2022; aftermarket support for the installed fleet, including maintenance, overhauls and original spare parts, continues through the service network. Send the M-series designation exactly as stamped.
What is the arrangement number, and where do I find it?
It identifies the specific configuration the engine was built and shipped as, and it sits on the same plate as the serial number. Parts research on this maker is done against the serial number and the arrangement number together; the serial number begins with a three-character prefix that belongs to a build family and a plant, and one model can have been built under several prefixes. Where the plate is missing, the serial number is normally stamped on the block and the arrangement number appears in the engine file kept on board.
Is Vessel Core connected to Caterpillar?
No, and there is no agreement of any kind. Vessel Core holds no dealership, distribution, representation or partnership agreement with Caterpillar, and quoting a component against one of its designations implies no approval by the maker and no claim of interchangeability.
Submit your RFQ now.
Send your Caterpillar spare parts request — vessel name, engine model (e.g. CAT 3512, C32), part numbers or descriptions, and port/ETA. Vessel Core reviews the supply route and prepares a structured supply quotation.
