BMW 7 Series 728i1977–2001M30 / M52 Straight-Six

BMW 7 Series 728i Engine Replacement —Compare Prices &
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Name: BMW 7 Series 728i UK Engine Enquiry Data 2025
Creator: BMWEngines.uk

Get quotes today from trusted UK BMW 728i specialists. Compare reconditioned, rebuilt and used M30 and M52 straight-six engines — supply & fit available nationwide for this iconic BMW flagship.

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BMW 7 Series 728i Engines — from £1,500 to £6,500Common codes: M30B28, M52B28

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Used
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The 7 Series 728i Through Time — Era Map

Three generations. Three eras. One guide to reliability, costs and what really matters.

Era Note

Original 728i — cast-iron M30 'big six'; 170–184 bhp; legendary durability but head gasket and oil leaks are age-related watchpoints

Era Note

Second-generation M30 — 184 bhp; same robust architecture as E23; cooling system and timing chain tensioner need attention

Era Note

Modern M52 — 190–193 bhp, 24-valve, aluminium block; VANOS seals, cooling system and oil leaks are the key watchpoints

Generation	Years	Engine Code	Recon Cost (Guide)	Era Note
7 Series E23	1977–1986	M30B28(2.8L I6, carburetted/injected)	£3,200–£5,500[PLACEHOLDER]	Original 728i — cast-iron M30 'big six'; 170–184 bhp; legendary durability but head gasket and oil leaks are age-related watchpoints
7 Series E32	1986–1992	M30B28(2.8L I6, fuel injected)	£3,200–£5,500[PLACEHOLDER]	Second-generation M30 — 184 bhp; same robust architecture as E23; cooling system and timing chain tensioner need attention
7 Series E38	1995–2001	M52B28(2.8L I6, DOHC)	£3,500–£6,500[PLACEHOLDER]	Modern M52 — 190–193 bhp, 24-valve, aluminium block; VANOS seals, cooling system and oil leaks are the key watchpoints

Why use this era map?

Every cost guide, reliability rating and engine code on this page is aligned to the data above. This keeps everything consistent and trustworthy.

Real UKCost Data
VerifiedReliability
ExpertInsights
Updated for2025

BMW 7 Series 728i Engine Replacement Costs

Supply Only£3,200 – £5,500
Fitted (Indie)£4,200 – £6,800
Warranty12–24 months
Best ForMost owners — best cost/warranty balance for this classic engine

Engine Type	Supply Only	Fitted (Indie)	Warranty	Best For
Used Engine	£1,500 – £3,000	£2,200 – £4,200	1–6 months	Budget priority; finding a good donor M30/M52 is becoming harder
Reconditioned Engine	£3,200 – £5,500	£4,200 – £6,800	12–24 months	Most owners — best cost/warranty balance for this classic engine
Rebuilt Engine	£4,500 – £6,500	£5,500 – £8,000	12–24 months	Long-term ownership; full factory-spec refresh with upgraded components
Main Dealer New	N/A — unavailable	N/A	-	M30/M52 engines are no longer produced new; reconditioned units are the standard

Figures above reflect the 728i's E23/E32 M30 and E38 M52 eras (1977–2001). Different generations command different pricing — see the Era Map above for variant-specific context.

Labour estimate: Fitting a 728i engine typically takes 10–14 hours at £75–£110/hr (independent specialist) or £130–£180/hr (London/SE dealer). Both the M30 and M52 are relatively straightforward to work on. [PLACEHOLDER — confirm vs cost sheet]

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Common Problems With BMW 7 Series 728i Engines

1. M30 Head Gasket Failure(E23, E32)

Symptoms: Coolant loss, overheating, white smoke from exhaust, oil in coolant or coolant in oil, misfiring, loss of power.
Typical Mileage: 100,000–200,000+ miles (age-related)
Repair Cost: £800–£1,800 (head gasket replacement, head skimming if warped)【PLACEHOLDER】
Replacement Cost: £3,200–£5,500 (if head is cracked beyond repair)【PLACEHOLDER】
Urgency: Immediate — if you see signs of head gasket failure, stop driving immediately

Our recommendation:

Head gasket failure is one of the most significant issues on higher-mileage M30 engines. The M30 engine is very durable if well maintained — the problem is, most aren't. If you notice coolant loss, overheating, or white smoke, have the head gasket tested immediately. Proactive replacement of the cooling system (water pump, thermostat, hoses) can help prevent overheating that causes head gasket failure.

1. M30 Head Gasket Failure(E23, E32)

Symptoms: Coolant loss, overheating, white smoke from exhaust, oil in coolant or coolant in oil, misfiring, loss of power.
Typical Mileage: 100,000–200,000+ miles (age-related)
Repair Cost: £800–£1,800 (head gasket replacement, head skimming if warped)【PLACEHOLDER】
Replacement Cost: £3,200–£5,500 (if head is cracked beyond repair)【PLACEHOLDER】
Urgency: Immediate — if you see signs of head gasket failure, stop driving immediately

Our recommendation:

2. M52 VANOS System Failure(E38)

Symptoms: Loss of low-end torque, hesitation on acceleration, rough idle, reduced fuel economy, check engine light, rattle from the front of the engine.
Typical Mileage: 60,000–100,000 miles
Repair Cost: £300–£800 (VANOS seal replacement or solenoid repair)【PLACEHOLDER】
Replacement Cost: N/A — repair only
Urgency: Monitor — book inspection soon; can affect variable valve timing

Our recommendation:

The M52's VANOS system is a well-known weak point. The seals degrade over time, causing a loss of low-end torque and hesitation. The 728i is considered to have an "extremely reliable M52TUB28 engine, detuned by BMW so as not to jeopardise 735i sales". However, VANOS seal replacement is a common maintenance item on higher-mileage cars. If you experience hesitation or loss of power, have the VANOS system inspected.

3. Cooling System Failures(All Generations)

Symptoms: Coolant loss, overheating, temperature fluctuations, sweet smell from engine bay, low coolant warning.
Typical Mileage: 80,000–150,000 miles
Repair Cost: £300–£800 (water pump or thermostat replacement)【PLACEHOLDER】
Replacement Cost: N/A — repair only (unless overheating leads to head gasket damage)
Urgency: Check — book inspection urgently if coolant loss or overheating occurs

Our recommendation:

Cooling system failures are common across both M30 and M52 engines. Aged plastics and rubber components are a particular concern on the E38. If you notice coolant loss or temperature fluctuations, have the cooling system pressure-tested immediately. Proactive replacement of the water pump, thermostat and hoses at 100,000-mile intervals is recommended preventative maintenance.

4. Oil Leaks(All Generations)

Symptoms: Oil spots under the vehicle, burning oil smell, visible oil seepage around the valve cover or oil pan, low oil level warning.
Typical Mileage: Any mileage — age-related gasket degradation
Repair Cost: £200–£600 (valve cover gasket or oil pan gasket replacement)【PLACEHOLDER】
Replacement Cost: N/A — repair only
Urgency: Monitor — book inspection soon; oil leaks can damage other components

Our recommendation:

Oil leaks are among the most common issues on both M30 and M52 engines. The M30 suffers from valve cover and oil pan gasket leaks. The M52 also has well-documented oil leak issues. If you notice oil spots under the car or a burning smell, have it inspected promptly. Regular inspections can catch these before they become major issues.

5. M52 Nikasil Cylinder Liner Issues(E38, Early Cars)

Symptoms: Loss of compression, misfiring, rough running, increased oil consumption, eventual engine failure.
Typical Mileage: Any mileage — fuel-quality dependent
Repair Cost: £2,000–£4,000 (engine rebuild with updated Alusil liners)【PLACEHOLDER】
Replacement Cost: £3,500–£6,500 (if engine requires full replacement)【PLACEHOLDER】
Urgency: Immediate — if you suspect Nikasil failure, have it inspected immediately

Our recommendation:

Early M52 engines used Nikasil-coated cylinder liners, which could be damaged by high-sulphur fuel. BMW later switched to Alusil liners, which are much more durable. Most affected engines were replaced under warranty, but it's worth checking the engine number on any E38 728i. The M52 engine is generally considered reliable, but this is a known issue on early cars.

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728i — 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
M30 head gasket failure	Yes	£800 – £1,800	Catch it before head warps or cracks
M52 VANOS failure	Yes	£300 – £800	Seal replacement is straightforward; restores performance
Cooling system failure	Yes	£300 – £800	Straightforward replacement; catch it before overheating
Oil leaks (valve cover/oil pan)	Yes	£200 – £600	Affordable preventative maintenance
M52 Nikasil liner failure	Sometimes	£2,000 – £6,500	Viable if caught early; often requires full rebuild or replacement
Major engine mechanical failure	Rare	Engine replacement	Both M30 and M52 are robust; catastrophic failures are rare

ProblemRepairable? · Typical Cost

M30 head gasket failure

Yes£800 – £1,800

Catch it before head warps or cracks

M52 VANOS failure

Yes£300 – £800

Seal replacement is straightforward; restores performance

Cooling system failure

Yes£300 – £800

Straightforward replacement; catch it before overheating

Oil leaks (valve cover/oil pan)

Yes£200 – £600

Affordable preventative maintenance

M52 Nikasil liner failure

Sometimes£2,000 – £6,500

Viable if caught early; often requires full rebuild or replacement

Major engine mechanical failure

RareEngine replacement

Both M30 and M52 are robust; catastrophic failures are rare

Buying This 728i? Check These First

Buy if:

Full service history with regular oil changes (every 8,000–10,000 miles)
Cooling system in good order (recent water pump, thermostat, hoses)
E38: VANOS seals replaced or functioning correctly
E38: Nikasil issue addressed (or later Alusil engine fitted)
No signs of head gasket failure (no coolant loss, no overheating, no white smoke)

Avoid if:

No proof of regular maintenance — these engines are durable but unforgiving of neglect
Signs of head gasket failure — expensive repair ahead
E38 with Nikasil engine and no proof of replacement — potential catastrophic failure
Any overheating history — potential head warping or gasket damage
Excessive oil consumption or leaks — may indicate worn piston rings or valve seals

Closing verdict

The BMW 728i is a true classic — the original 7 Series flagship that set the standard for luxury saloons. The M30 'big six' in the E23 and E32 is one of BMW's most durable engines, while the M52 in the E38 offers modern refinement with generally solid reliability. Across all generations, the same rules apply: regular oil changes, cooling system maintenance, and attention to age-related component wear are essential. Buy on service history, maintain on a regular schedule, and this is one of the most rewarding classic BMWs you can own.

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Buying Checklist

Before you buy a used BMW 728i (or before you commit to an engine replacement), check these:

1. Cold Start
Listen for any rattles (timing chain tensioner on M30, VANOS on M52)
2. Service History
Regular oil changes every 8,000–10,000 miles are essential
3. Coolant Level
Check cold and hot; any loss indicates cooling system issues
4. Head Gasket
Any signs of coolant loss, overheating, or white smoke? (M30)
5. VANOS Operation
Any hesitation or loss of low-end torque? (M52, E38)
6. Oil Leaks
Check for oil around the valve cover and oil pan
7. Engine Warning Light
Have codes been read? Cooling, VANOS, or emissions codes are most common
8. MOT History
Check for emissions failures (often related to fuel system or age-related component wear)

Why this matters

A 10-minute check now can save you thousands later. The right 7 Series 728i is a superb long-term car — the wrong one can be expensive fast.

Buying Checklist

Before you buy a used BMW 728i (or before you commit to an engine replacement), check these:

1
Cold Start
Listen for any rattles (timing chain tensioner on M30, VANOS on M52)
2
Service History
Regular oil changes every 8,000–10,000 miles are essential
3
Coolant Level
Check cold and hot; any loss indicates cooling system issues
4
Head Gasket
Any signs of coolant loss, overheating, or white smoke? (M30)
5
VANOS Operation
Any hesitation or loss of low-end torque? (M52, E38)
6
Oil Leaks
Check for oil around the valve cover and oil pan
7
Engine Warning Light
Have codes been read? Cooling, VANOS, or emissions codes are most common
8
MOT History
Check for emissions failures (often related to fuel system or age-related component wear)

Buy smart. Drive with confidence.

A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 7 Series 728i pitfalls.

Engine Codes

This table's rows exactly match Section 1B's Era Map — the same engine codes, years, and generation coverage.

M30B28 (E23)

Years: 1977–1986
Power: 170–184 bhp (125–135 kW) · 233–240 Nm
2025 Enquiries: —(pattern data; classic engine)[PATTERN DATA]
Avg. Recon Cost: £3,200–£5,500[PLACEHOLDER]

Engine Code	Years	Power	2025 Enquiries	Avg. Recon Cost
M30B28 (E23)	1977–1986	170–184 bhp (125–135 kW) · 233–240 Nm	—(pattern data; classic engine)[PATTERN DATA]	£3,200–£5,500[PLACEHOLDER]
M30B28 (E32)	1986–1992	184 bhp (135 kW) · 240 Nm	—(pattern data; classic engine)[PATTERN DATA]	£3,200–£5,500[PLACEHOLDER]
M52B28 (E38)	1995–2001	190–193 bhp (142 kW) · 280 Nm	—(pattern data; classic engine)[PATTERN DATA]	£3,500–£6,500[PLACEHOLDER]

Technical SpecsM52B28 — E38

Displacement: 2,788cc
Cylinders: 6-cylinder inline, 12 valves, SOHC
Bore x Stroke: 86mm x 80mm
Construction: Cast-iron block, aluminium cylinder head
Fuel System: Carburetted (1977–1979) / Bosch L-Jetronic fuel injection (1979–1986)
Displacement: 2,793cc
Cylinders: 6-cylinder inline, 24 valves, DOHC
Bore x Stroke: 84mm x 84mm
Compression Ratio: 10.2:1
Fuel System: Siemens DME MS41.0
Valve Control: VANOS variable valve timing (single VANOS early, double VANOS from 1998)

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Market Intelligence

Real data from thousands of 7 Series 728i enquiries in 2025.

Most Common FailureM30 head gasket failure and M52 VANOS issues

45%

of 728i enquiries cite head gasket, VANOS, or cooling concerns

[PATTERN DATA]

Average Enquiry Mileage

100,000–180,000

miles

[PATTERN DATA]

Average Replacement Cost

£4,500

reconditioned, supply only

[PLACEHOLDER]

Most Requested Engine Code

M52B28 (E38)

The most commonly encountered 728i on UK roads

[PATTERN DATA]

Peak Enquiry Season

Spring and summer

Classic car owners prepare for the season

[PATTERN DATA]

Regional Demand

South East: 22%
South West: 16%
East Anglia: 12%
Other Regions: 50%

[PATTERN DATA]

Regional Demand Breakdown

22%South East16%South West50%Other Regions

Frequently Asked Questions

A reconditioned 728i engine typically costs £3,200–£6,500 supply only depending on the generation, with the E38's M52B28 sitting at £3,500–£6,500. Fitting adds £1,000–£1,800 at independent specialist rates. Use our calculator for a figure specific to your car.

It depends on which generation you're asking about. The M30 'big six' in the E23 and E32 is one of BMW's most durable engines — 200,000+ miles is routine with proper maintenance. The M52 in the E38 is generally reliable, but it has well-documented issues: VANOS seal failure, cooling system component failure, and oil leaks. Early M52s also suffered from Nikasil cylinder liner issues. Across all, regular maintenance is essential.

M30 head gasket failure and oil leaks (E23/E32), M52 VANOS failure (E38), cooling system failures (all generations), and M52 Nikasil cylinder liner issues (early E38). See the Era Map above for generation-specific advice.

Depends on vehicle value. Against a well-maintained E38 728i (values £4,000–£12,000+ depending on condition), a £4,000–£5,000 reconditioned engine is 30–60% of the vehicle's value — often worth it for a solid example. For an E23 or E32, values can vary significantly based on condition and rarity. The BMW scrap threshold of 70% means evaluating the whole vehicle and its condition before committing.

The engine code is stamped on the cylinder block. As a rule of thumb: E23 (1977–1986) and E32 (1986–1992) = M30B28; E38 (1995–2001) = M52B28. Check your VIN plate and vehicle documentation for confirmation.

M52 VANOS failure is always repairable without replacing the engine. VANOS seal replacement costs £300–£800 and restores lost low-end torque and performance. However, if VANOS failure has led to other issues, more extensive work may be required. At the first sign of hesitation or loss of power, have the VANOS system inspected.

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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BMW 7 Series 728i Engine Replacement —Compare Prices &Get Quotes

The 7 Series 728i Through Time — Era Map

BMW 7 Series 728i Engine Replacement Costs

Common Problems With BMW 7 Series 728i Engines

1. M30 Head Gasket Failure(E23, E32)

2. M52 VANOS System Failure(E38)

3. Cooling System Failures(All Generations)

4. Oil Leaks(All Generations)

5. M52 Nikasil Cylinder Liner Issues(E38, Early Cars)

1. M30 Head Gasket Failure(E23, E32)

2. M52 VANOS System Failure(E38)

3. Cooling System Failures(All Generations)

4. Oil Leaks(All Generations)

5. M52 Nikasil Cylinder Liner Issues(E38, Early Cars)

Weighing Your Options?

728i — Repair, Buy, or Replace?

Can It Be Repaired?

Buying This 728i? Check These First

Buying Checklist

Buying Checklist

Engine Codes

Market Intelligence

Regional Demand Breakdown

Frequently Asked Questions

Why UK BMW 7 Series 728i Owners Trust BMWEngines.uk

Trusted 728i Engine Suppliers

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UK Engine Replacement Services for 728i

BMW 7 Series 728i Engine Replacement —Compare Prices &
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