When a workshop replaces a cylinder head, a crankshaft or a gearbox, the repair is finished, but the part is not. Where it goes next decides whether it ends up as scrap, as raw material or as a working component in another vehicle. In our first article on sustainability and diesel vehicle maintenance we listed responsible disposal and recycling of replaced parts as one of four areas that matter. This article looks at how truck parts recycling works in practice for four of the heaviest and most valuable parts on a diesel vehicle.
Three routes for a replaced part
Every removed part follows one of three routes, in this order of preference:
- Reuse: the part is still sound and goes back into service, either as it is or after testing.
- Reconditioning: the part is worn but the basic casting or forging is intact, so it is machined, fitted with new wear components and tested.
- Material recycling: the part is beyond repair, so the metal is recovered and returned to industry.
Scrapping a part that could have taken route one or two wastes the energy and material that went into making it. That is why a part should be assessed before it is thrown away, not after.
Cylinder heads: tested, machined, back in service
A cylinder head is a large casting that carries the valves, valve seats and injectors as well as the coolant and oil passages. It is usually removed after overheating, a failed head gasket or a damaged valve, and in many of these cases the casting itself is still usable.
A removed head is cleaned, pressure-tested for cracks and checked for flatness on the sealing face. If it passes, the sealing face can be skimmed within the permitted limits, valve seats and guides renewed and the valves reground, and the head returns to service as a used or reconditioned part. A head with cracks between the valve seats or in the water jacket goes to material recycling, where the casting is melted down. You can see what is available in our cylinder heads group.
Engine blocks: the base an engine is rebuilt on
The engine block, or crankcase, is the heaviest single part of the engine and the base everything else is built on. Even after serious engine damage, the block is often not the part that failed.
A block is cleaned, crack-tested and measured at the cylinder bores, the main bearing bores and the deck surface. Depending on the design and the result, the cylinders are honed or fitted with new liners, the main bearing bores are line-bored and the deck face is machined flat. The block can then be built up again as a short block or long block. Only a block with cracks in load-bearing areas or in the water jacket is recycled as cast metal. Our engine blocks group shows the blocks currently available.
Crankshafts: forged once, used many times
A crankshaft is a forged steel component and one of the most expensive single parts of the engine. It is often replaced because of a bearing failure, an oil supply problem or damage elsewhere in the engine, not because the shaft itself is finished.
A removed crankshaft is cleaned and checked for cracks, straightness and journal dimensions. If the journals are within limits, the shaft can go on as a used part. If they are worn, they can often be ground to an undersize and paired with matching bearings. Only a shaft with cracks or deep damage goes to material recycling, where the steel is melted down and reused. You can see what is available in our crankshafts group.
Gearboxes: housings and gear sets outlast the truck
A gearbox is a good example of why reuse beats scrapping. Housings, shafts and gear sets are made for a very long life, and in many cases the failure is limited to one component: a worn synchroniser, a damaged bearing or a leaking shaft seal. A gearbox from a vehicle that was written off after an accident is often mechanically sound.
Such a unit is drained, inspected, turned through and checked for play. Where needed, wear parts are renewed, and the gearbox is sold as a used or reconditioned unit. Only housings with cracks or severe wear in the bores are recycled as metal. Browse our complete gearboxes if you need a replacement.
What is recycled and what is not
Recycling is not a blanket approach. In our experience:
- Good candidates: forged and cast components, cylinder heads, engine blocks, housings, crankshafts, camshafts, gear sets, complete gearboxes.
- Material recycling only: cracked castings, heads and blocks with damaged water jackets, parts with unmeasurable fatigue damage.
- Never refitted: safety-critical wear parts such as brake linings, belts, filters and seals.
Why it matters for your fleet
For a fleet operator, recycled parts are not only an environmental choice. They are typically available faster than a new part from the manufacturer, they cost less, and they keep an older vehicle on the road instead of forcing an early replacement. The metal does not need to be produced from ore again, and the energy used to make the original part is not lost. If you want to see how we assess and condition used components, read our article on giving used truck parts a second chance.
Ask us about your part
Tell us the part number, engine type or chassis number of the component you need, and we will check availability and all condition options, whether used, reconditioned or new. You receive an offer within 24 hours.