Sourcing diesel generator engines from China

Generator-engine duty: normally 4%

Heading 8408 covers compression-ignition piston engines. This guide concerns diesel engines supplied to drive generators, rather than complete generating sets, which fall under heading 8502. The relevant engine lines distinguish used engines from new engines and split new engines by power. See the wider diesel engines guide for other applications.

Read from the UK Trade Tariff on 1 October 2026, the selected lines carried 4% duty for goods from China, with no anti-dumping or countervailing measures and no attached import controls. Some lower-power lines list conditional 0% suspensions for specified vehicle manufacture or vehicle-mounted temperature-control applications. These are not general relief for generator engines; budget using 4% unless the exact suspension conditions are met.

Give your customs broker the engine specification, rated power, intended use and new or used condition. Confirm the commodity code before shipment, particularly when the supplier offers an engine together with an alternator.

Specify the engine for the generator load

State whether the engine will drive a transportable generator or a permanently installed set. For new non-road mobile machinery sold in Great Britain, confirm the applicable engine type-approval and marking requirements with the relevant authority. Ask for any applicable approval documents and photographs of the engine label for the exact model; have the intended application checked before ordering.

Specify mechanical output at the intended governed speed, continuous or standby duty, cooling arrangement and the load taken by accessories. Agree flywheel and housing dimensions, mounting points, rotation direction, controller connections and supplied exhaust equipment. An engine power figure alone does not establish the electrical output of the finished generator.

Agree a witnessed bench test using the ordered configuration, recording output, speed stability, temperatures and leaks. List included starter equipment, radiator, filters and sensors, and agree service instructions and spare-part identification. Use testing and certification support to review the evidence for the intended application.

Worked duty example

Illustrative example, not a quote: Illustrative order: 2 new diesel generator engines under 8408 90 45 90, invoiced at £8,000 free on board, with £200 of freight and insurance to the UK. The customs value is £8,200. Duty at 4% is £328. Import VAT at 20% is charged on the customs value plus duty, £8,528, so it is £1,705.60. Import taxes total £2,033.60; a VAT-registered importer can usually reclaim the VAT, so the lasting cost is the £328 of duty. The import duty and VAT guide explains each step.

Inspection checklist

Identity: match model, serial number, engine label and approval documents to the purchase specification.

Performance: witness cold starting, loaded running and load changes; compare output and speed stability with the agreed test criteria.

Interfaces: check flywheel, housing, mounts, cooling connections, wiring and sensors against the generator assembly drawings.

Arrival: inspect crates, corrosion, loose fittings and fluid leakage; compare accessories with the packing list and retain photographs. Plan quality inspection before dispatch and on receipt.

What goes wrong

A supplier may quote peak output at a different speed, omit the cooling fan load or substitute a governor or controller. The engine can then struggle with the intended generator load despite appearing to match the catalogue rating. Tie acceptance to the ordered configuration and the agreed bench test.

Approval documents for a different engine family, missing exhaust equipment, incompatible sensor wiring and leaks after running can delay assembly. Check document identity before production and repeat the physical checks before shipment. A successful power test does not establish emissions compliance; confirm any approval requirements for the intended new non-road mobile machinery application with the relevant authority.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For machinery and equipment, see machinery imports.