Z Series M54 Engines
from £1,495 to £3,500
Rebuilt units from £1,495 · Common codes: M54B30, M54B25, M54B22, M52B28
Get quotes from UK BMW Z4 performance engine specialists. Compare rebuilt & reconditioned engines for sDrive20i to M40i - N52/N54/B58 covered. Find UK performance engine specialists.
Z Series M54 Engines
from £1,495 to £3,500
Rebuilt units from £1,495 · Common codes: M54B30, M54B25, M54B22, M52B28
Z Series N52 Engines
from £1,695 to £3,800
Rebuilt units from £1,695 · Common codes: N52B30, N52B25, N53B30, N46B20
Z Series M Performance Engines
from £4,500 to £9,000
Rebuilt units from £4,500 · Common codes: S54B32, S50B32, S62B50

Most replacements completed within 3-5 days.
The table shows typical UK rebuilt engine replacement costs for BMW Z Series variants, covering known failures, engine codes, fuel types and sizes from current market data.


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Not sure which variant your BMW Z Series is- Enter your registration number above - we'll identify the exact sub-model, engine code and compatible replacement options instantly.

Every engine code fitted to the BMW Z Series across all generations, with technical specs, compatible variants and trims, known failure points, and average rebuilt prices from UK specialists. Select any engine code to compare quotes.
Extracted from detailed petrol and performance engine families across BMW Z Series variants.

M44B19 - 1.9L Petrol
Main replacement demand comes from timing-chain, cooling-system and performance thermal-management faults.
Compatible variants
Avg. rebuilt price
£1,200 - £2,400
Supply only
Technical specifications
Common failures
Not sure which engine code?
Can’t find your engine code- Enter your registration number above - we’ll instantly identify the exact unit, its technical specifications, and live replacement prices from UK BMW Z Series engine specialists. Every rebuilt engine comes with a minimum 12-month unlimited mileage warranty.

The BMW Z Series delivers exceptional driving dynamics, but its ageing straight-six and early turbo petrol units face predictable wear as they cross the 60,000-mile threshold. Replacement demand is heavily driven by M54 cooling system degradation, N52 Valvetronic wear, and N20/N54 forced-induction failures. Every rebuilt engine supplied through our network...
BMW Z Series M54 Cooling System & CCV Failure
Most affected vehicles
BMW Z Series Z3 3.0i, Z4 3.0i (2000-2008, M54B30)
Failure mileage range
60,000 - 90,000 miles
Typical failure window
Root cause
The plastic expansion tank, water pump impeller, and thermostat housing become brittle under repeated thermal cycling, while the crankcase ventilation valve diaphragm ruptures, causing lean running and excessive oil consumption.
Repair options & estimated costs (UK ranges)
| Repair tier | Dealer price | Specialist price | What it involves | Longevity / suitability |
|---|---|---|---|---|
| Minor - Preventative Cooling Overhaul | £900 - £1,400 | £500 - £850 | Replacement of water pump, thermostat, expansion tank, hoses and CCV assembly with updated materials | Extends lifespan by 40,000+ miles if caught before overheating |
| Major - Cylinder Head Reseal & Cooling | £2,200 - £3,500 | £1,400 - £2,200 | Full gasket set replacement, head skim, crack pressure test, cooling system overhaul | Viable only if cylinder block and bottom end remain undamaged |
| Full Replacement - Rebuilt / Reconditioned Engine | £4,500 - £6,500 | £1,800 - £3,200 | Supply & fit of fully rebuilt M54 unit with upgraded bearings, reinforced cooling components and bench testing | Restores factory performance with warranty-backed reliability |
Our recommendation
For a BMW Z Series valued between £3,000 and £8,000, a preventative cooling and CCV overhaul is highly cost-effective if performed at the first signs of weeping or slow coolant loss. However, if the engine has already overheated and suffered a warped head or cracked block, a specialist rebuilt unit is the only reliable long-term solution.
Compare rebuilt M54B30 engine prices for your BMW Z Series
Every replacement condition is available through our UK network, with typical price ranges shaped by your exact variant, engine code and budget.
Compare BMW Z Series engine prices with vetted UK suppliers
All engine types include a minimum 12-month unlimited mileage warranty when sourced through EngineMarket. Prices are typical UK market ranges based on historical quote data from our network and depend on exact engine code, variant, mileage and supplier. Use our free comparison tool above - enter your registration to get tailored quotes for your specific BMW Z Series within hours.

Every displacement fitted to the BMW Z Series is listed below with compatible engine codes, production years and common failure notes to help you identify the correct replacement unit.
The 1.8L four-cylinder was the entry-level powerplant for the early E85 Z4, offering accessible running costs while retaining the roadster's balanced chassis dynamics. Naturally aspirated and equipped with BMW's Valvetronic variable valve lift system, it prioritised smoothness and efficiency over outright performance, making it a practical choice for high-mileage drivers.
Engine Code(s)
N46B18
Compatible Models (UK)
Z4 1.8i
Power output
Verified by registration
Common Failure Points
Valvetronic motor wear, timing chain tensioner rattle, oil leaks from valve cover, oil filter housing gaskets
Production Years: E85, 2003-2008
Compare BMW Z Series 1.8L petrol engine prices
Choose your BMW Z Series engine by fuel type to compare realistic replacement prices, known issues, and compatible UK supply options - from the classic Z3 1.9i four-cylinder to the latest G29 Z4 M40i B58 turbo.
The BMW Z Series has exclusively used petrol powertrains in the UK, spanning naturally aspirated inline-six classics to modern turbocharged units, with replacement demand concentrated on M54, N52, N54 and S54 engine families.
Common BMW Z Series Petrol Engine Families
Found In
Known For
Typical Petrol Models
The BMW Z Series has exclusively used petrol powertrains in the UK, spanning naturally aspirated inline-six classics to modern turbocharged units, with replacement demand concentrated on M54, N52, N54 and S54 engine families.
Common BMW Z Series Petrol Engine Families
Found In
Known For
Typical Petrol Models
Not sure which fuel type your BMW Z Series has- Enter your registration number above to instantly identify your engine code, fuel system and compatible replacement options - all backed by a minimum 12-month unlimited mileage warranty from UK BMW Z Series specialists.

This technical timeline covers every major engine change across the BMW Z Series production run (1989-present), organised so UK owners can quickly identify their engine code, model year and compare rebuilt engine prices from specialist suppliers.
⚙Key Changes
▣Main Engines
M20B25- 2.5L petrol (Z1 2.5i)
▰Popular Models
🔧Known For
Engine Codes Covered:
M20B25