BMW 3 Series 318i1982–present7 Engine Families

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Name: BMW 318i UK Engine Enquiry Data 2025
Creator: BMWEngines.uk

The 318i is one of BMW's longest-running badges — spanning carburettor M10s, early fuel-injected M40s, twin-cam M42s, N-series Valvetronic units, and modern turbocharged B-series engines. Get quotes from UK specialists for reconditioned, rebuilt and used units today.

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BMW 318i Engines — from £500 to £5,000Common codes: M10B18, M40B18, M42B18, M43B18, N42B18, N46B18, N43B18

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No Obligation
100% Free
Reconditioned
Rebuilt
Used
Supply & Fit Available
UK-Wide Network

BMW 318i Engine Replacement Costs

Supply Only£1,000 – £2,500
Fitted (Indie)£2,000 – £3,800
Warranty12–24 months
Best ForMost owners — best cost/warranty balance

Engine Type	Supply Only	Fitted (Indie)	Warranty	Best For
Used Engine	£500 – £1,500	£1,000 – £2,500	1–6 months	Budget priority; older M10/M40/M42 examples
Reconditioned Engine	£1,000 – £2,500	£2,000 – £3,800	12–24 months	Most owners — best cost/warranty balance
Rebuilt Engine	£1,800 – £4,500	£3,000 – £6,000	12–24 months	Long-term ownership; 3+ year horizon
Main Dealer New	£4,000 – £8,000	£5,500 – £10,000	24–36 months	Insurance jobs, warranty claims

Figures above reflect the current 318i market. Older M10/M40/M42 engines sit at the lower end; N-series and B-series engines command a premium. See the Era Map above for generation-specific context.

Labour estimate: Fitting a 318i engine typically takes 8–14 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer).

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Common Problems With BMW 3 Series 318i Engines

1. Timing Belt Failure(M10, M40, M43)

Symptoms: Engine stops suddenly, loss of power, ticking from the front of the engine, complete engine failure
Typical Mileage: 40,000–60,000 miles (belt interval)
Repair Cost: £300–£600 (preventative timing belt replacement)
Replacement Cost: £600–£1,500 (if belt snaps — piston-valve contact)
Urgency: Immediate — if the belt fails, the engine stops instantly and internal damage is highly likely

Our recommendation:

The M10, M40 and M43 engines use timing belts (not chains). BMW recommends replacement every 40,000–60,000 miles or 4–5 years. A snapped timing belt on these interference engines means valve and piston damage — effectively an engine replacement. If you're buying an older 318i with any of these engines, demand proof of timing belt replacement. Budget for it immediately if there's no evidence.

Read the full timing belt failure guide /failures/timing-chain-diagnosis-guide

1. Timing Belt Failure(M10, M40, M43)

Symptoms: Engine stops suddenly, loss of power, ticking from the front of the engine, complete engine failure
Typical Mileage: 40,000–60,000 miles (belt interval)
Repair Cost: £300–£600 (preventative timing belt replacement)
Replacement Cost: £600–£1,500 (if belt snaps — piston-valve contact)
Urgency: Immediate — if the belt fails, the engine stops instantly and internal damage is highly likely

Our recommendation:

Read the full timing belt failure guide /failures/timing-chain-diagnosis-guide

2. Timing Chain and VANOS Issues(N42/N46)

Symptoms: Rattling noise on cold start lasting 2–5 seconds, metallic ticking, engine warning light, loss of low-end power (VANOS failure)
Typical Mileage: 60,000–100,000 miles
Repair Cost: £800–£1,800 (timing chain, tensioner, guide and VANOS rebuild)
Replacement Cost: £1,200–£2,200 (if chain jumps and causes valve interference)
Urgency: Immediate — any cold-start rattle on N42/N46 requires immediate investigation

Our recommendation:

The N42 and N46 Valvetronic engines introduced complexity with timing chain and VANOS issues. The chain guides can fail, and the VANOS solenoids and seals degrade. Cold-start rattle is the defining warning sign. A preventative chain and VANOS rebuild is cheaper than a full engine replacement. If buying an E46 318i, ensure the chain has been checked or budget for the work.

Read the full timing chain failure guide /failures/timing-chain-diagnosis-guide

3. Timing Chain and Injector Issues(N43/N45 Direct Injection)

Symptoms: Rattling on cold start, rough idle, misfire under load, vibration, engine warning light, poor fuel economy
Typical Mileage: 50,000–100,000 miles
Repair Cost: £600–£1,800 (timing chain replacement or injector replacement/cleaning)
Replacement Cost: £1,500–£2,800 (if chain jumps and causes valve interference)
Urgency: Immediate — any cold-start rattle on N43/N45 requires immediate investigation

Our recommendation:

The N43 and N45 direct-injection engines are the least reliable of the 318i family. They suffer from timing chain issues and injector problems that cause vibration and rough running. Carbon build-up on intake valves is also a known issue. If buying an E90 318i, budget for timing chain work and injector cleaning or replacement. The N43 is widely considered the worst 318i engine in terms of reliability.

Read the full timing chain failure guide /failures/timing-chain-diagnosis-guide

4. Timing Chain and Oil Consumption(N13 Prince Turbo)

Symptoms: Rattling on cold start, oil level dropping between services, blue smoke on startup, rough idle, engine warning light
Typical Mileage: 60,000–100,000 miles
Repair Cost: £1,200–£2,500 (timing chain replacement and PCV system service)
Replacement Cost: £1,800–£3,000 (if chain jumps and causes valve interference)
Urgency: Immediate — any cold-start rattle on N13 requires immediate investigation

Our recommendation:

The N13 is a Prince-family engine derived from the PSA/BMW collaboration. It has a poor reputation for timing chain wear and oil consumption. BMW didn't formally recognise the timing chain issue in the UK/EU, so preventative replacement is essential. At the first sign of cold-start rattle, book an inspection immediately. A preventative chain replacement is far cheaper than a full engine replacement. Check oil levels regularly — N13s are known for oil consumption.

Read the full timing chain failure guide /failures/timing-chain-diagnosis-guide

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318i — Repair, Buy, or Replace?

Not every issue means a new engine.Here’s what can be repaired, when it makes sense, and what to check before you buy.

Can It Be Repaired?

Problem	Repairable?	Typical Cost	When It Makes Sense
Timing belt replacement (M10/M40/M43)	Yes	£300 – £600	Standard maintenance — the most important investment in older 318is
Timing belt failure (engine damage)	Usually No	Engine replacement	If belt snaps, valves hit pistons — replacement is the only option
Timing chain tensioner (N42/N46/N43/N13)	Yes	£800 – £2,500	Far cheaper than a full engine — the single most important investment on these engines
Timing chain failure (engine damage)	Usually No	Engine replacement	If chain jumps and valves hit pistons, replacement is the only option
VANOS failure (N42/N46)	Yes	£400 – £1,000	Rebuild or replace — well-understood by BMW specialists
Injector issues (N43/N45)	Yes	£400 – £1,200	Replacement and cleaning — catch before catalyst damage
Oil consumption (N13)	Yes	£200 – £600	PCV valve replacement or oil separator service
Cooling system leaks (B38/B48)	Yes	£400 – £1,000	Straightforward replacement — catch before overheating

ProblemRepairable? · Typical Cost

Timing belt replacement (M10/M40/M43)

Yes£300 – £600

Standard maintenance — the most important investment in older 318is

Timing belt failure (engine damage)

Usually NoEngine replacement

If belt snaps, valves hit pistons — replacement is the only option

Timing chain tensioner (N42/N46/N43/N13)

Yes£800 – £2,500

Far cheaper than a full engine — the single most important investment on these engines

Timing chain failure (engine damage)

Usually NoEngine replacement

If chain jumps and valves hit pistons, replacement is the only option

VANOS failure (N42/N46)

Yes£400 – £1,000

Rebuild or replace — well-understood by BMW specialists

Injector issues (N43/N45)

Yes£400 – £1,200

Replacement and cleaning — catch before catalyst damage

Oil consumption (N13)

Yes£200 – £600

PCV valve replacement or oil separator service

Cooling system leaks (B38/B48)

Yes£400 – £1,000

Straightforward replacement — catch before overheating

Buying This 318i? Check These First

Buy if:

B38/B48-engined car (2019+) — the most reliable 318i generation by some margin
M10/M40/M42/M43 with documented timing belt replacement — evidence of regular belt changes
N42/N46/N43/N13 with documented timing chain work — the defining question on these engines
Full service history with correct BMW-spec oil (varies by era)

Avoid if:

N42/N46/N43/N13 with no proof of timing chain work — you're buying a known risk
N43/N45 with vibration and rough idle — injector or timing chain issues incoming
N13 with oil consumption issues — often indicates PCV or ring problems
Any cold-start rattle on any era — this is almost always timing belt (older) or timing chain (newer) wear
Poor service history — these engines are unforgiving of neglect

Closing verdict

The 318i badge spans seven entirely different engine families over four decades. The early M10 and M40 engines are simple and robust but require timing belt attention. The M42/M44 twin-cam 16v engines are enthusiast favourites with excellent reliability. The N42/N46 Valvetronic engines introduced complexity and timing chain issues. The N43 direct-injection engines are the least reliable. The N13 Prince turbo has a poor reputation. The B38/B48 (2019+) are genuinely reliable modern engines. Buy on history, not on badge.

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Buying Checklist

Before you buy a used BMW 318i (or before you commit to an engine replacement), check these:

1. Timing Belt History (M10/M40/M43)
Has it been changed within the last 40,000–60,000 miles?
2. Cold Start (all engines)
Any rattles? (timing belt or chain warning depending on era)
3. Service History
Including which engine era and evidence of timing belt/chain work
4. Oil Level
Check for excessive consumption (N13 warning) or coolant contamination
5. Idle Quality
Any vibration or roughness? (injector or VANOS issues on later engines)
6. Coolant Level
Any loss? (cooling system issues on all generations)
7. Engine Warning Light
Have codes been read? Any unresolved issues?
8. MOT History
Check for emissions-related failures (catalyst, O2 sensors)

Why this matters

A 10-minute check now can save you thousands later. The right 3 Series 318i is a superb long-term car — the wrong one can be expensive fast.

Buying Checklist

Before you buy a used BMW 318i (or before you commit to an engine replacement), check these:

1
Timing Belt History (M10/M40/M43)
Has it been changed within the last 40,000–60,000 miles?
2
Cold Start (all engines)
Any rattles? (timing belt or chain warning depending on era)
3
Service History
Including which engine era and evidence of timing belt/chain work
4
Oil Level
Check for excessive consumption (N13 warning) or coolant contamination
5
Idle Quality
Any vibration or roughness? (injector or VANOS issues on later engines)
6
Coolant Level
Any loss? (cooling system issues on all generations)
7
Engine Warning Light
Have codes been read? Any unresolved issues?
8
MOT History
Check for emissions-related failures (catalyst, O2 sensors)

Buy smart. Drive with confidence.

A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 3 Series 318i pitfalls.

Engine Codes

This table's rows match Section 1B's Era Map exactly — nine engine families across the 318i's history.

M10B18

Years: 1982–1987
Power: 90–105 hp
2025 Enquiries: [PATTERN DATA]
Avg. Recon Cost: £600–£1,200[BMW-QUOTE]

Engine Code	Years	Power	2025 Enquiries	Avg. Recon Cost
M10B18	1982–1987	90–105 hp	[PATTERN DATA]	£600–£1,200[BMW-QUOTE]
M40B18	1987–1991	113 hp	[PATTERN DATA]	£700–£1,400[BMW-QUOTE]
M42B18	1989–1991 (E30) / 1990–1996 (E36)	136–140 hp	[PATTERN DATA]	£800–£1,600[BMW-QUOTE]
M43B18	1990–1998	115 hp	[PATTERN DATA]	£700–£1,500[BMW-QUOTE]
M44B19	1996–1998	140 hp	[PATTERN DATA]	£800–£1,600[BMW-QUOTE]
N42B18 / N46B18	1998–2005	115–143 hp	[PATTERN DATA]	£1,200–£2,200[BMW-QUOTE]
N43B18 / N45B18	2005–2012	122–143 hp	[PATTERN DATA]	£1,500–£2,800[BMW-QUOTE]
N13B18	2012–2018	136 hp	[PATTERN DATA]	£1,800–£3,000[BMW-QUOTE]
B38A15 / B48A20	2019–present	109–184 hp	[PATTERN DATA]	£2,200–£4,500[BMW-QUOTE]

Technical SpecsB38A15 — current generation

Displacement: 1,499cc (1.5-litre)
Cylinders: 3-cylinder inline
Compression Ratio: 11:1
Fuel System: Direct injection
Turbocharger: Single-scroll turbocharger

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Market Intelligence

Real data from thousands of 3 Series 318i enquiries in 2025.

Most Common FailureTiming belt (M10/M40/M43) / Timing chain (N42/N46/N43/N13)

The defining risk of each generation

Average Enquiry Mileage

70,000–120,000

miles

[PATTERN DATA]

Average Replacement Cost

£600–£4,500

reconditioned, supply only depending on generation

[BMW-QUOTE]

Most Requested Engine Code

N43B18

The direct-injection generation (unfortunately, due to its poor reliability)

[PATTERN DATA]

Peak Enquiry Season

Winter

Cold starts expose timing belt/chain issues

[PATTERN DATA]

Regional Demand

London: 20%
South East: 18%
North West: 12%
Other Regions: 50%

[PATTERN DATA]

Regional Demand Breakdown

20%London18%South East12%North West50%Other Regions

Frequently Asked Questions

A reconditioned 318i engine typically costs £600–£4,500 supply only depending on which generation, with used units available from £500–£1,500 for older engines. Fitting adds £700–£2,000. Use our calculator for a figure specific to your car.

It depends entirely on which of the nine engine generations your 318i has. The M10/M40/M42/M43/M44 engines are robust but ageing. The N42/N46 Valvetronic engines introduced timing chain issues. The N43 direct-injection engines are the least reliable. The N13 turbo has a poor reputation for timing chain and oil consumption. The B38/B48 (2019+) are genuinely reliable. Check the Era Map above for your specific car.

M10/M40/M43: timing belt failure (requires regular replacement). M42/M44: generally reliable — check VANOS and cooling system. N42/N46: timing chain and VANOS issues. N43/N45: timing chain, injector and carbon build-up issues. N13: timing chain and oil consumption. B38/B48: oil filter housing and cooling system leaks. The B38/B48 is the most reliable generation.

Depends on vehicle value and generation. Against a well-kept G20 318i worth £15,000+, a £2,500–£4,500 recon is only 15–30% — worth it. Against a tired £1,500 E30 318i, a £1,500 recon exceeds 70% — get a scrap valuation first. The value of the car matters more than the engine.

Listed on the VIN plate and vehicle documentation. The 318i has used nine distinct engine families. Tell us your registration date and we'll confirm it for free.

On M10/M40/M43 engines, the timing belt must be replaced — it's a wear item. Replacement interval is 40,000–60,000 miles or 4–5 years. If the belt snaps, the engine is typically destroyed. On N42/N46/N43/N13 engines, the timing chain and tensioner need replacement if they show wear — preventative replacement is far cheaper than a full engine replacement. At the first sign of cold-start rattle on any 318i, book an inspection immediately.

Disclaimer: All prices are indicative UK market ranges based on historical quote data from our network of engine specialists.
Actual costs vary by variant, engine code, damage severity and workshop location. Use our free comparison tool to get tailored quotes.
Every engine supplied through EnginesMarket carries a minimum 12-month unlimited-mileage warranty — always confirm terms with your chosen supplier.

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every garage and engine rebuilder in our network is vetted, rated and reviewed by real 318i owners, as part of the Engine Finders network, across every engine generation from M10 to B38 — no matter which era your 3 Series belongs to.
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see prices, warranty terms and supply & fit options side‑by‑side before you commit, with specialists who genuinely understand the timing belt, timing chain, VANOS, and cooling system nuances of each 318i generation.
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supply‑only or full supply & fit available nationwide, covering every generation of this badge since 1982 with a 12‑month warranty as standard.

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BMW 318i Engine Replacement Costs

Common Problems With BMW 3 Series 318i Engines

1. Timing Belt Failure(M10, M40, M43)

2. Timing Chain and VANOS Issues(N42/N46)

3. Timing Chain and Injector Issues(N43/N45 Direct Injection)

4. Timing Chain and Oil Consumption(N13 Prince Turbo)

1. Timing Belt Failure(M10, M40, M43)

2. Timing Chain and VANOS Issues(N42/N46)

3. Timing Chain and Injector Issues(N43/N45 Direct Injection)

4. Timing Chain and Oil Consumption(N13 Prince Turbo)

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318i — Repair, Buy, or Replace?

Can It Be Repaired?

Buying This 318i? Check These First

Buying Checklist

Buying Checklist

Engine Codes

Market Intelligence

Regional Demand Breakdown

Frequently Asked Questions

Why UK BMW 3 Series 318i Owners Trust BMWEngines.uk

Trusted 318i Engine Suppliers

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