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1.0 EcoBoost vs M50 and M52: which engine is more reliable?

According to our risk index, the M50 and M52 carries less risk than the 1.0 EcoBoost: 52/100 versus 71/100 (both high risk). The 1.0 EcoBoost has 3 documented serious faults, the main one being «Degradation of the timing belt running in oil»; the M50 and M52 has 2 documented serious faults, the main one being «Cooling system failure (expansion tank, thermostat, pump and radiator)».

Risk index

1.0 EcoBoost

71

High risk · 3 serious faults

Risk index

M50 and M52

52

High risk · 2 serious faults

Lower risk

The index (0–100) weights the severity and frequency of the three most serious documented faults. How it is calculated

21 sourcesHow we work

Is the 1.0 EcoBoost reliable?

It is a turbocharged direct-injection three-cylinder that has won Engine of the Year several times, but it has two very well-documented weak points: two belts running in oil (timing and oil pump) that can disintegrate and seize the engine, and cases of coolant leaks and overheating in early units. It is best bought with a service history and the belts checked or replaced on time.[1][2][3][4]

See the 4 of the 1.0 EcoBoost faults

Is the M50 and M52 reliable?

The M52 and its predecessor the M50 are six-cylinder petrol engines that the sources describe as durable: Enginescope considers 300,000 km routine with the cooling circuit looked after. Watch the plastic cooling parts, VANOS, crankcase ventilation and oil leaks and, in the aluminium-block M52s built from 1995 to March 1998, cylinder wear caused by sulphur (Nikasil).[5][6][7]

See the 5 of the M50 and M52 faults

Side-by-side comparison

Comparison of 1.0 EcoBoost and M50 and M52
1.0 EcoBoostM50 and M52
Technical data
TypeEngineEngine
FuelPetrolPetrol
Displacement999 cm³—
TimingWet belt (belt-in-oil)Chain
Power100–155 hp150–193 hp
Productionsince 2012[1][8][9][10]1990–2001[11][12][13][14]
Reliability
Risk index (what is it?)71High risk52High risk
Documented faults45
Of high or critical severity32
Worst severityCritical severityCritical severity
Main faults
  1. Critical severity: Degradation of the timing belt running in oil
  2. Critical severity: Oil pump belt and tensioner failure
  3. Critical severity: Coolant leaks and overheating from the turbo hose
  1. High severity: Cooling system failure (expansion tank, thermostat, pump and radiator)
  2. Critical severity: Premature cylinder wear (Nikasil coating)
  3. Medium severity: Worn VANOS seals
Most expensive documented repairup to €1,200Degradation of the timing belt running in oilPublished figure[2]No reliable data
Which versions to buy
BuyRecommended versionsNoneNone
With cautionVersions to be cautious about
  • 1.0 EcoBoost 100/125 (Fox, 2012-2017)[2][3][15]
  • 1.0 EcoBoost 100/125/140 with cylinder deactivation (from ~2017)[16][17]
  • 1.0 EcoBoost Hybrid 48V mild hybrid (125/155 hp, from 2019)[1][18]
  • M50B20, 2.0 litre (150 hp; 1990-1995)[19][20]
  • M50B25, 2.5 litre (192 hp; 1990-1995)[19][20]
  • M52B20, 2.0 litre (150 hp; 1994-1999)[12][19]
  • M52B25, 2.5 litre (170 hp; 1995-1999)[12][19]
  • M52B28, 2.8 litre (193 hp; 1995-1999)[12][19][21]
  • M52TUB20, 2.0 litre (150 hp; 1998-2001)[11][19]
  • M52TUB25, 2.5 litre (170 hp; 1998-2000)[11][19]
  • M52TUB28, 2.8 litre (193 hp; 1998-2001)[7][11][19]
AvoidVersions to avoidNoneNone

Severity of each fault: green, low; amber, medium; red, high; dark red, critical. How we rate them

Cars that each one is fitted to

1.0 EcoBoost

See the 12 models with the 1.0 EcoBoost

M50 and M52

Other comparisons

With the 1.0 EcoBoost

With the M50 and M52

Compare other engines

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Sources

Every fact on this page links to its source. If you find an error, let us know.

  1. Ford EcoBoost engineWikipedia · Encyclopedia · consulted 26 September 2026
  2. Alerta Ford: la correa de distribución del 1.0 EcoBoost puede romper el motor y la NHTSA ya investigaMotor16 · Motoring press · consulted 26 September 2026 · in Spanish
  3. Los Ford 1.0 EcoBoost tricilíndricos están dando problemas de correas bañadas que recuerdan al caso PureTechMotor.es · Motoring press · consulted 26 September 2026 · in Spanish
  4. Gripa el motor por problema en el manguito se queda sin refrigeranteOpinautos · Owners' forum · consulted 26 September 2026 · in Spanish
  5. BMW 3 Series E36 320i (M52B20): reliabilityEnginescope · Buying guide or workshop · consulted 2 November 2026
  6. BMW M52 reliabilityAutoscore · Buying guide or workshop · consulted 2 November 2026
  7. BMW M52 Engine: Performance, Reliability, and TuningBMWBlog · Motoring press · consulted 2 November 2026
  8. Prueba: Ford Fiesta 1.0 EcoBoost 100 CV (2013)km77 · Motoring press · consulted 26 September 2026 · in Spanish
  9. Ford Mondeo Berlina Trend 1.0 EcoBoost 92 kW (125 CV) (2015-2018): precio y ficha técnicakm77 · Technical documentation · consulted 26 September 2026 · in Spanish
  10. Ford B-MAX Trend 1.0 EcoBoost 100 CV (2012-2018): precio y ficha técnicakm77 · Technical documentation · consulted 26 September 2026 · in Spanish
  11. BMW M52Wikipedia (inglés) · Encyclopedia · consulted 2 November 2026
  12. BMW M52Wikipedia (alemán) · Encyclopedia · consulted 2 November 2026 · in German
  13. BMW M50Wikipedia (inglés) · Encyclopedia · consulted 2 November 2026
  14. BMW M50Wikipedia (alemán) · Encyclopedia · consulted 2 November 2026 · in German
  15. Ford EcoBoost engines: reliability, problems and should you buy one?Carbuyer · Motoring press · consulted 26 September 2026
  16. Ford's Self-Clogging 1.0-Liter EcoBoost Engine Is Finally Getting RecalledThe Drive · Motoring press · consulted 26 September 2026
  17. The Largest Ford EcoBoost Recalls In 15 Years Of ProductionCarBuzz · Motoring press · consulted 26 September 2026
  18. Stellantis no es el único afectado por la correa de distribución bañada en aceiteAutofácil · Motoring press · consulted 26 September 2026 · in Spanish
  19. BMW M50 / M52: problemas conocidosEnginescope · Buying guide or workshop · consulted 2 November 2026
  20. Der BMW M50 Motor: Technische Daten, Probleme, Haltbarkeit & FahrzeuglisteCarWiki.de · Buying guide or workshop · consulted 2 November 2026 · in German
  21. BMW Z3 Reliability Guide: Everything You Need to Know Before BuyingEuro Premium Parts · Technical documentation · consulted 2 November 2026