Description
Thornycroft TK-40 43hp Marine Diesel Engine & Gearbox Package – Professional Overview
The Thornycroft TK-40 is a four-cylinder marine diesel engine package developed for vessel repowering and new installation requirements. Its 43hp output at 2,600 rpm provides a practical balance of propulsion performance, controlled engine speed, and suitability for a wide range of marine applications.
This package is supplied as a complete propulsion solution rather than as a standalone engine. The standard configuration includes the PRM 125D2 gearbox, control panel, 4.0M wiring extension harness, and flexible engine mountings. This makes the package particularly relevant to boat owners and marine professionals planning an engine replacement where the propulsion system needs to be supplied as an integrated package.
The engine uses heat exchanger cooling, providing a freshwater-cooled engine system appropriate for marine propulsion installations. The supplied electrical and control components also provide the essential connection between the engine and vessel controls.
The product is stated to be fully CE and RCD II compliant for leisure and commercial use, making compliance an important consideration for buyers planning a professionally specified repower.
The engine shown in product imagery may display the optional PRM150D2 gearbox. The standard package is supplied with the PRM 125D2 unless an alternative gearbox is selected.
Compatibility, Applications, and Technical Context
The Thornycroft TK-40 marine diesel engine is intended for applications where a dependable four-cylinder diesel propulsion system is required. Its 43hp rating makes it suitable for a variety of leisure and commercial marine vessels, subject to correct vessel sizing, shafting, gearbox ratio, propeller selection, and installation requirements.
The standard package incorporates a PRM 125D2 gearbox, while several alternative gearbox configurations can be specified. Available options include the PRM150 D1.5, PRM150 D2, PRM150 D3, PRM280 D2, PRM280 D3, Technodrive TM345A1.5, Technodrive TM345A2.0, and Technodrive TM345A2.47.
For projects where the existing propulsion system needs to be retained, the engine can also be supplied as a bobtail marine diesel engine without a gearbox or configured with an adaptor for an existing gearbox.
Adaptor and drive plate combinations are available for PRM125, PRM150, TMC60, PRM260, PRM280, Borg Warner, ZF Hydraulic, and SAE7 applications. Selecting the correct configuration requires consideration of the existing installation and drivetrain arrangement.
The package therefore provides flexibility for both straightforward repower projects and installations requiring more specific drivetrain integration.
Construction, Cooling, and Performance
The Thornycroft TK-40 43hp diesel engine uses a four-cylinder configuration with a 2.2-litre cylinder capacity. The engine is specified with freshwater cooling through a heat exchanger system, helping maintain controlled operating temperatures during marine use.
Its rated output is 43hp (32kW) at 2,600 rpm. This operating speed is appropriate for a marine propulsion system where the engine, gearbox, shaft, and propeller must work together as a matched drivetrain.
The supplied flexible engine mountings help accommodate the engine within a properly prepared installation. Correct alignment remains important when installing any marine diesel engine and gearbox combination.
The standard control equipment can be selected according to the requirements of the installation. Buyers can choose between Standard and Deluxe Control Panels, while extension harnesses are available in 4.0M, 6.0M, and 8.0M configurations. The harness connectors are fully waterproofed to suit the marine operating environment.
The package can also be configured with additional equipment such as a PTO stub shaft on the crank, hot water connections for a calorifier, a deck wash pump, or a second 100A alternator.
Gearbox and Installation Options
One of the major advantages of the Thornycroft TK-40 marine engine package is the range of drivetrain configurations available.
The standard package includes the PRM 125D2 gearbox, while buyers can specify other PRM or Technodrive units where the vessel’s propulsion requirements call for a different gearbox arrangement.
Available gearbox choices include:
- PRM150 D1.5
- PRM150 D2
- PRM150 D3
- PRM280 D2
- PRM280 D3
- Technodrive TM345A1.5
- Technodrive TM345A2.0
- Technodrive TM345A2.47
For existing installations, adaptor and drive plate options provide additional flexibility. These include configurations for PRM125, PRM150, TMC60, PRM260, PRM280, Borg Warner, ZF Hydraulic, and SAE7 applications.
This makes the Thornycroft TK-40 43hp Marine Diesel Engine & Gearbox Package relevant to replacement projects where compatibility with an existing drivetrain is a central consideration.
Control Systems and Optional Equipment
The standard package includes a control panel and 4.0M wiring extension harness. Depending on the installation, customers can select a Standard or Deluxe Control Panel and choose a 4.0M, 6.0M, or 8.0M extension harness.
The available waterproofed harness connectors provide a practical solution for connecting the engine’s electrical and control systems to the vessel.
Additional options can be specified for installations requiring expanded functionality. These include a PTO stub shaft on the crank, hot water connections for a calorifier, a deck wash pump, and a second 100A alternator.
These options allow the engine package to be configured around the requirements of the vessel rather than restricting the buyer to one fixed specification.
Technical Specification
| Specification | Details |
|---|---|
| Product | Thornycroft TK-40 Marine Diesel Engine & Gearbox Package |
| Manufacturer | Thornycroft |
| Engine Type | Inboard Marine Diesel |
| Power Output | 43hp (32kW) |
| Rated Speed | 2,600 rpm |
| Cylinders | 4 |
| Displacement | 2.2L |
| Fuel | Diesel |
| Cooling System | Freshwater / Heat Exchanger Cooled |
| Starter | Electric Start |
| Standard Gearbox | PRM 125D2 |
| Standard Control Equipment | Control Panel |
| Standard Wiring Harness | 4.0M Extension Harness |
| Engine Mounting | Flexible Engine Mountings |
| Control Panel Options | Standard or Deluxe |
| Harness Options | 4.0M, 6.0M, 8.0M |
| Gearbox Options | PRM150, PRM280 and Technodrive options available |
| Installation Configuration | Gearbox, Bobtail, or Existing Gearbox Adaptor |
| Compliance | CE and RCD II compliant |
| Intended Use | Leisure and Commercial Marine |
| Condition | New |
| Year Built | 2025 |
| Manufacturer Category | Thornycroft Marine Diesel Engine |
Why This Package Works for Repower Projects
A marine repower involves more than selecting an engine with the correct horsepower. The gearbox, mounting arrangement, control system, wiring, cooling configuration, and connection to the existing drivetrain all influence the final installation.
The Thornycroft TK-40 43hp Marine Diesel Engine & Gearbox Package addresses several of these requirements in one package. The standard specification provides the engine, PRM gearbox, flexible mounts, control panel, and wiring harness, while additional configurations are available when the installation requires a different drivetrain or control arrangement.
The availability of bobtail configurations and gearbox adaptors can also be useful when replacing an existing engine while retaining elements of the vessel’s current propulsion system.
For buyers comparing marine diesel engines in the 40hp class, the TK-40 provides a four-cylinder, 2.2L diesel configuration with a 43hp output and a broad selection of installation options.
Who This Product Is Best For
The Thornycroft TK-40 43hp Marine Diesel Engine & Gearbox Package is suited to boat owners, marine engineers, boatyards, commercial operators, and vessel owners planning a diesel repower.
It is particularly relevant when a buyer needs a complete marine engine and gearbox package rather than an engine alone. The multiple gearbox, adaptor, control panel, and harness options also make it appropriate for installations where the existing drivetrain configuration needs to be considered.
The package is specified for both leisure and commercial marine use, with CE and RCD II compliance stated as part of the product specification.
Ordering, Availability, and Support
Most standard-specification models are stated to be in stock ready for delivery, while bespoke configurations generally have a 6–8 week lead time.
Because gearbox ratios, adaptor plates, control systems, harness lengths, and optional equipment can affect the final configuration, buyers should confirm the required specification before ordering.
Trade-in availability is also part of the supplied commercial offering. A qualifying old engine can be exchanged under the stated trade-in scheme, including running or non-running units manufactured after 1980.
For a repower project, providing details of the existing engine, gearbox, vessel, and installation arrangement can help establish the appropriate configuration.
Frequently Asked Questions
What is the horsepower of the Thornycroft TK-40?
The Thornycroft TK-40 produces 43hp at 2,600 rpm, equivalent to approximately 32kW. It uses a four-cylinder, 2.2L diesel engine configuration and is designed for marine propulsion applications in leisure and commercial vessels.
What gearbox comes with the standard package?
The standard Thornycroft TK-40 engine package includes a PRM 125D2 gearbox. Other gearbox options are available, including PRM150, PRM280, and Technodrive configurations. The correct gearbox should be selected according to the vessel and propulsion system requirements.
Can the TK-40 be supplied without a gearbox?
Yes. The engine can be supplied as a bobtail configuration without a gearbox. It can also be supplied with an adaptor to suit an existing gearbox, providing flexibility for repower projects where the current drivetrain needs to be retained.
Is the Thornycroft TK-40 suitable for commercial vessels?
The supplied product information states that the engine is fully CE and RCD II compliant for leisure and commercial use. Its final suitability for a particular commercial vessel depends on the vessel’s propulsion requirements and applicable installation requirements.
What control panel and wiring options are available?
The engine can be supplied with either a Standard or Deluxe Control Panel. Extension harnesses are available in 4.0M, 6.0M, and 8.0M lengths, with fully waterproofed harness connectors for marine installation environments.
What additional options can be specified?
Available options include a PTO stub shaft on the crank, hot water connections for a calorifier, deck wash pump, and second 100A alternator. These options can be specified according to the requirements of the vessel and installation.
Does the product include flexible engine mountings?
Yes. The standard package includes flexible engine mountings, together with the PRM 125D2 gearbox, control panel, and 4.0M wiring extension harness. Additional configuration options can be specified for different installation requirements.
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