Buying a used engine or gearbox: what to check
Last updated: 3 Nov 2026
A replacement engine or gearbox from a breaker often costs a fraction of a new or reconditioned one. It's also the purchase where checking matters most, because fitting one is a big labour bill.
Match the codes, not just the size
Find the engine code on your engine (stamped on the block or on a sticker) and ask for the code on theirs. For gearboxes, match the gearbox code, the number of gears, and manual or automatic. Diesel engines can also differ in injection system and emissions parts between years, so match the year range too. More on finding the right part.
Questions to ask the seller
- What mileage was the car it came from? Can you send a photo of the dashboard?
- Have you heard it running, or seen the car driven in?
- Why was the car broken: accident damage (usually good for the engine) or a mechanical fault?
- What's included: ancillaries (turbo, injectors, alternator, starter), wiring loom, ECU?
- What warranty do you give, and does it need a garage to fit it?
Before it goes in
- Change the cambelt or timing chain if its history isn't known, and the oil and filter.
- Check the ECU and keys: some engines need their ECU coded to the car, or the original ECU moving across.
- Keep the paperwork, in case you need the warranty.
Find one
Search for your engine or gearbox by reg and compare breakers and eBay listings in one list. Search now.