BMW 7 Series E23Saloon1977–1986

BMW 7 Series E23 Engines -The Complete UK Guide

Every engine fitted to the E23 -from the 2.5-litre M30 four-cylinder that launched BMW's first 7 Series to the 3.5-litre M88 in the South African 745i and the turbocharged M102/M106 that redefined luxury performance. Real UK replacement costs, honest reliability data, and the fuel injection and cooling system quirks that define this classic generation. Backed by real UK E23 enquiries in 2025 [BMW-VERIFIED].

Explore E23 Engines
E23Enquiries (2025)BMW-VERIFIED
Saloon
11+Engine Codes
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BMW 7 Series E23 Engine Codes -The Complete Database

Every engine fitted to the E23 -from the entry-level carburetted four-cylinder to the range-topping M88-powered 745i SA.

Engine CodeFuelPowerYearsReliabilityEnquiriesAvg. Recon Cost
M30B25VM30Petrol150 PS (110 kW)1977–1979★★★★☆ [PROVISIONAL]-(pattern data)£1,200–£2,500 [BMW-QUOTE]
M30B25M30Petrol150 PS (110 kW)1981–1986★★★★☆ [PROVISIONAL]-(pattern data)£1,200–£2,500 [BMW-QUOTE]
M30B28VM30Petrol170 PS (125 kW)1977–1979★★★★☆ [PROVISIONAL]-(pattern data)£1,500–£3,000 [BMW-QUOTE]
M30B28M30Petrol184 PS (135 kW)1979–1986★★★★☆ [PROVISIONAL]-(pattern data)£1,800–£3,500 [BMW-QUOTE]
M30B30VM30Petrol184 PS (135 kW)1977–1979★★★★☆ [PROVISIONAL]-(pattern data)£2,000–£4,000 [BMW-QUOTE]
M30B32M30Petrol197 PS (145 kW)1979–1986★★★★½ [PROVISIONAL]-(pattern data)£2,500–£5,000 [BMW-QUOTE]
M30B32 (US)M30Petrol173–181 hp (129–135 kW)1977–1984★★★★☆ [PROVISIONAL]-(pattern data)£2,500–£5,000 [BMW-QUOTE]
M90M90Petrol218 PS (160 kW)1979–1982★★★★½ [PROVISIONAL]-(pattern data)£3,000–£6,000 [BMW-QUOTE]
M30B34M30Petrol218 PS (160 kW)1982–1986★★★★½ [PROVISIONAL]-(pattern data)£3,000–£6,000 [BMW-QUOTE]
M102M30Petrol Turbo252 PS (185 kW)1980–1982★★★★☆ [PROVISIONAL]-(pattern data)£4,000–£7,000 [BMW-QUOTE]
M106M30Petrol Turbo252 PS (185 kW)1983–1986★★★★☆ [PROVISIONAL]-(pattern data)£4,500–£8,000 [BMW-QUOTE]
M88/3M88Petrol286 PS (210 kW)1984–1986★★★★½ [PROVISIONAL]-(pattern data)£5,000–£10,000 [BMW-QUOTE]
BMW 3 Series E90

Overview

BMW 7 Series E23 -Overview

The BMW E23, launched in May 1977, is the first generation of the 7 Series and the flagship of the BMW range.

Designed by Paul Bracq and Manfred Rennen, it replaced the New Six (E3) sedans and established BMW's presence in the full-size luxury segment. Initially powered by carburetted and fuel-injected M30 straight-six engines, the E23 introduced many electronic features for the first time in a BMW, including an on-board computer, service interval indicator, and a "check control" warning system. From 1980, turbocharged engines were available, and a rare South African variant used the M88/3 engine from the M1.

Key Facts

Platform

BMW E23 (first-generation 7 Series)

Predecessor

BMW New Six (E3)

Successor

BMW 7 Series E32 (1986–1994)

Sibling body styles in this generation

None (E23 was 4-door saloon only)

Market Intelligence

The E23 generated real UK engine enquiries in 2025 [BMW-VERIFIED], with the M30B32 (732i/733i) and M90/M30B34 (735i) accounting for the majority of demand as these cars enter classic collector territory.

Best & Worst Engines

M30B34 (735i, 1982–1986) – "The later 3.4-litre M30 with Motronic injection delivers 218 PS of smooth, linear power with improved reliability over earlier L-Jetronic cars. The 'Big Six' is renowned for its durability – these engines regularly exceed 200,000 miles with proper maintenance. Cooling system and fuel injection are the only real demands." engine

Best Petrol Overall

M30B34 (735i, 1982–1986) – "The later 3.4-litre M30 with Motronic injection delivers 218 PS of smooth, linear power with improved reliability over earlier L-Jetronic cars. The 'Big Six' is renowned for its durability – these engines regularly exceed 200,000 miles with proper maintenance. Cooling system and fuel injection are the only real demands."

“”

Who it's for: buyers who want the definitive E23 driving experience.

M102/M106 (745i, turbocharged) – "The early turbocharged M30 engines are complex – the KKK turbocharger, charge-air cooling and fuel enrichment systems can be problematic. Parts are increasingly difficult to source, and specialist knowledge is essential. Boost pressure and fuel system issues can lead to catastrophic engine failure if ignored." engine

Highest Risk

M102/M106 (745i, turbocharged) – "The early turbocharged M30 engines are complex – the KKK turbocharger, charge-air cooling and fuel enrichment systems can be problematic. Parts are increasingly difficult to source, and specialist knowledge is essential. Boost pressure and fuel system issues can lead to catastrophic engine failure if ignored."

“”

Who it's for: only buyers who are comfortable with classic turbocharged systems and have a dedicated maintenance budget.

M88/3 (South African 745i) – "The M88/3 is a rare and valuable engine – essentially a detuned version of the M1's engine with individual throttle bodies and 286 PS. Parts are extremely expensive and specialist-only. A full rebuild can exceed £10,000." engine

Most Expensive Failure

M88/3 (South African 745i) – "The M88/3 is a rare and valuable engine – essentially a detuned version of the M1's engine with individual throttle bodies and 286 PS. Parts are extremely expensive and specialist-only. A full rebuild can exceed £10,000."

“”

Who it's for: collectors and enthusiasts with very deep pockets.

M30B28 (728i, 1979–1986) – "The 2.8-litre injected M30 delivers 184 PS with excellent economy for a large saloon. No turbocharger complexity, no carburettor to fiddle with – just a solid, reliable six-cylinder that will run forever with basic maintenance. It's the entry point to E23 ownership." engine

Best Value

M30B28 (728i, 1979–1986) – "The 2.8-litre injected M30 delivers 184 PS with excellent economy for a large saloon. No turbocharger complexity, no carburettor to fiddle with – just a solid, reliable six-cylinder that will run forever with basic maintenance. It's the entry point to E23 ownership."

“”

Who it's for: buyers who want classic 7 Series presence with minimal maintenance headaches.

M30B32 (732i/733i, 1979–1986) – "The 3.2-litre engine is often overlooked in favour of the 735i, but it delivers 197 PS with virtually identical reliability and lower running costs. The Motronic injection on later cars is a significant upgrade over early L-Jetronic systems. It's the sweet spot of the naturally aspirated range." engine

Most Overlooked

M30B32 (732i/733i, 1979–1986) – "The 3.2-litre engine is often overlooked in favour of the 735i, but it delivers 197 PS with virtually identical reliability and lower running costs. The Motronic injection on later cars is a significant upgrade over early L-Jetronic systems. It's the sweet spot of the naturally aspirated range."

“”

Who it's for: buyers who want six-cylinder refinement without the 735i's premium.

BMW 7 Series E23 -Ownership Economics

EngineTypical MileageCommon Major FailureRepair Cost (Specialist)Replacement Cost (Recon)Ownership Verdict
M30B25V/B25 (725/725i)80k–150kCarburettor/Injection, cooling£300–£600£1,200–£2,500
Solid – the entry-level E23.
M30B28V (728)80k–150kSolex carburettor, cooling£300–£600£1,500–£3,000
Solid – carburetted six, simple but thirstier.
M30B28 (728i)80k–150kL-Jetronic injection, cooling£300–£700£1,800–£3,500
Solid – reliable injected six, best value.
M30B30V (730)80k–150kSolex carburettor, cooling£300–£700£2,000–£4,000
Solid – rare, carburetted 3.0.
M30B32 (732i/733i EU)80k–150kL-Jetronic/Motronic, cooling£400–£800£2,500–£5,000
Best Value – the sweet spot of the range.
M30B32 (733i US)80k–150kThermal reactors, cooling£400–£800£2,500–£5,000
Watch – US emissions equipment adds complexity.
M90 (735i early)80k–150kL-Jetronic, cooling system£500–£1,000£3,000–£6,000
Collectable – the definitive early 735i.
M30B34 (735i late)80k–200kMotronic, cooling system£400–£800£3,000–£6,000
Best Petrol – the most refined naturally aspirated E23.
M102 (745i early)60k–120kTurbocharger, fuel enrichment£800–£2,000£4,000–£7,000
Watch – complex turbo system; specialist-only.
M106 (745i late)60k–120kTurbocharger, Motronic, cooling£800–£2,000£4,500–£8,000
Watch – improved but still complex.
M88/3 (745i SA)40k–80kValves, timing chain, injection£1,000–£2,500£5,000–£10,000
Expensive – M1-derived engine; serious specialist territory.

The E23 rule

A £2,500–£5,000 M30B32 recon against a £2,000–£8,000 E23 sits at 31–250% of the car's value. On a sub-£4,000 example, that brushes our 70% BMW threshold – we'll honestly tell you to walk away unless the car is exceptional. Against a £7,000+ low-mileage example, the same recon drops to a routine 36–71% – a repair decision, not a financial one. For the 745i, values are high enough that even a £8,000 M106 rebuild is often a viable investment on a £10,000+ car.

Key Takeaways

  • Which E23 Costs Least To Own?

    M30B28 (728i) – simplest injected six, cheapest parts.

  • Which E23 Costs Most To Own?

    M88/3 (South African 745i) – rare, complex, expensive parts.

  • Which E23 Is Best Value?

    M30B32 (732i/733i) – the sweet spot between performance and running costs.

Common Problems

E23 Engine Replacement Costs -By Engine and Condition

Core Variants

Diesel & Petrol Lineup

Petrol Variants

725725i728728i730732i733i735i745i745i (SA)

Scope note: All variants listed are E23 only. The E32 (1986–1994) is the successor generation with its own engine line-up – see the E32 Generation Page for those specifications. The 745i (SA) is a rare South African variant using the M88/3 engine from the BMW M1.

Market Intelligence

Most Requested E90 Engines (2025)

  1. 1.1. M30B32 (732i/733i) – the sweet spot of the range
  2. 2.2. M90/M30B34 (735i) – flagship six-cylinder enquiries
  3. 3.3. M106 (745i) – turbocharged performance enquiries [PATTERN DATA].

Most Requested E90 Variants

  1. 1.1. 735i
  2. 2.2. 732i
  3. 3.3. 745i [PATTERN DATA].

Average E90 Replacement Cost

£1,200–£10,000 supply only [BMW-QUOTE].

Most Common E90 Failures

  1. 1.1. Cooling system failures (all engines)
  2. 2.2. Fuel injection system issues (injected models)
  3. 3.3. M30 head gasket failure
  4. 4.4. 4HP22 transmission issues [PATTERN DATA].
Live Feed
VehicleLocationIssueEnquiries
BMW 735i (M30B34)

BMW 735i (M30B34)

Birmingham
Overheating enquiry

4

enquiries

BMW 745i (M106)

BMW 745i (M106)

London
Turbocharger boost issue

2

enquiries

BMW 732i (M30B32)

BMW 732i (M30B32)

Manchester
Rough idle

2

enquiries

Updated Monthly

FAQ

BMW 3 Series E90 rear three-quarter view

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