Last updated: July 2026 — every price on this page was checked against the named UK sources on 8 July 2026.
A full engine rebuild costs £2,231–£4,884 in the UK (average £3,290, Checkatrade). The alternatives frame the decision: a used or reconditioned replacement engine runs £1,000–£5,000+ (ClickMechanic, Bumper), while a new engine fitted costs £4,500–£9,000 by car size (Bumper).
At these numbers, the car’s value decides as much as the engine does — the honest maths is below.
Rebuild, replace or repair: the price map
| Option | Published cost | Source |
|---|---|---|
| Engine repair (average booked quote) | £218.82 | FixMyCar |
| Used / reconditioned engine fitted | £1,000–£5,000+ | ClickMechanic |
| Secondhand/refurbished engine, by car size | £1,000–£4,000 | Bumper |
| Full engine rebuild | £2,231–£4,884 (avg £3,290) | Checkatrade |
| New engine, by car size | £4,500–£9,000 | Bumper |
Two honesty notes. The rebuild figure comes from a single source — Checkatrade is the only one of our five references publishing rebuild-specific prices, and its figures vary by location. And expect a wait either way: a full rebuild takes several days to a couple of weeks (Checkatrade).
What a rebuild actually involves
Per Checkatrade: replacing worn parts (pistons, bearings, seals), cleaning out carbon deposits and sludge, machining components back to correct fit, and reassembling to manufacturer specs. Done properly it “can extend the life of your vehicle by years, often at a lower cost than a brand-new engine or a new car” — the catch is that the block and head must be worth rebuilding: a cracked block or unobtainable parts tips the maths to replacement (Checkatrade).
Which option fits your failure?
- Repair — ClickMechanic’s guidance: top-end problems (a valve issue on one cylinder, a first head-gasket failure on a non-overheated engine, noisy tappets) can often be fixed without opening the bottom end.
- Rebuild — worn but sound engine, good car, long-term keeper (Checkatrade’s “good overall condition and you plan to keep it” test).
- Replace — ClickMechanic’s red flags: no oil pressure or a deep bottom-end knock rising with revs means bearing failure; running it “will destroy the crank”. A used or reconditioned unit usually beats rebuilding at that point.
- Scrap or sell — the RAC’s rule: if the repair costs more than the car is worth, you are better off moving on. Bumper’s practical advice: get a buying-as-is valuation from a garage or breaker and compare it against the quotes.
The value maths, worked through
Take a £6,000 car with a failed engine: a £2,500 reconditioned unit is ~40% of its value — defensible under the insurers’ 50–60% write-off threshold. The same engine in a £2,500 car costs 100% of its value: sell it as-is to a breaker (a car with a dead engine still beats the £200–£279 weight-based scrap averages if the body is good) and put the money towards the next car. Bumper’s warning applies especially to new engines: they “will often be more expensive than the value of the car”.
Frequently asked questions
How long does an engine rebuild take?
Several days to a couple of weeks (Checkatrade) — plan alternative transport. Engine swaps with a ready reconditioned unit are usually quicker than full rebuilds.
Is a reconditioned engine as good as a rebuild?
A properly reconditioned engine is essentially someone else’s rebuild with a warranty — often cheaper (£1,000–£4,000 by car size, per Bumper) and faster than rebuilding yours. Ask for the warranty terms and what was replaced.
My engine is knocking — can I drive to the garage?
A deep metallic knock that rises with revs is ClickMechanic’s classic bearing-failure sign, and driving on it can destroy the crank — turning a repairable engine into scrap. Recover the car; do not drive it.
Should I rebuild the engine or scrap the car?
Run the numbers: rebuild average £3,290 against the car’s repaired value, applying the 50–60% rule. On most cars worth under £4,000, a full rebuild fails that test — a used engine or selling as-is usually wins.
Related guides
- All engine repair cost guides
- Nissan Qashqai head gasket repair cost
- Wet belt failure: repair or scrap the car?
Sources: Checkatrade engine rebuilding, ClickMechanic engine replacement, Bumper, FixMyCar and the RAC, all checked 8 July 2026. See how we verify prices.