The Mitsubishi 4G54 is a 2,555 cc, inline‑four naturally aspirated petrol engine produced between 1977 and 2002. It features a single overhead camshaft (SOHC), 8 valves in early variants and 16 valves in later DOHC MIVEC versions, delivering 81–107 kW (110–145 PS) and 181–235 Nm of torque. Its cast‑iron block and robust bottom end prioritise durability and off‑road reliability over refinement.
Fitted to models such as the Pajero (L040), L200/Triton (K74), and Galant (A170), the 4G54 was engineered for global utility applications, from commercial fleets to recreational 4x4s. Emissions compliance was achieved through carburetion, throttle-body injection, or multi-point fuel injection depending on year, meeting Euro 1 standards in European markets during its later production run.
One documented concern is head gasket failure in high-compression or overheated DOHC variants, highlighted in Mitsubishi Service Bulletin ENG‑89‑014. This issue stems from thermal stress at the cylinder head interface, particularly when coolant maintenance is neglected or the engine is operated under sustained high load in hot climates.
Production years 1992–2002 meet Euro 1 standards in applicable markets (Japan Ministry of Land, Infrastructure, Transport and Tourism Type Approval #MLIT‑G4G54‑1993).
The Mitsubishi 4G54 is a 2,555 cc inline‑four naturally aspirated petrol engine engineered for SUVs, pickups, and sedans (1977–2002). It evolved from SOHC carburetted roots to DOHC multi-point injection with optional MIVEC, delivering strong low-end torque and field-proven ruggedness. Designed to meet Euro 1 emissions standards in later years, it balances mechanical simplicity with functional performance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,555 cc | |
| Fuel type | Petrol (Unleaded) | |
| Configuration | Inline‑4, SOHC 8V (early) / DOHC 16V (late) | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 91.1 mm × 98.0 mm | |
| Power output | 81–107 kW (110–145 PS) @ 4,500–6,000 rpm | |
| Torque | 181–235 Nm @ 2,500–4,000 rpm | |
| Fuel system | Carburettor / TBI / MPFI (model-dependent) | |
| Emissions standard | Euro 1 (1992–2002 models) | |
| Compression ratio | 8.5:1 (carb) – 9.5:1 (MPFI) | |
| Cooling system | Water‑cooled | |
| Turbocharger | None (naturally aspirated only) | |
| Timing system | Belt-driven SOHC or DOHC | |
| Oil type | API SG/SH, SAE 10W‑40 | |
| Dry weight | 168 kg |
The 4G54’s cast-iron construction provides excellent durability under load but requires strict adherence to 10,000 km timing belt replacement intervals to prevent interference damage in DOHC variants. Head gasket integrity is highly dependent on coolant condition—neglect or overheating significantly increases failure risk in high-compression MPFI versions. Use of API SG/SH 10W‑40 oil is essential; modern low-viscosity oils may not protect the older valvetrain. The engine’s simplicity aids field repairs, but emissions systems on Euro 1 models (EGR, catalytic converter) require periodic inspection to maintain compliance and drivability.
Oil Specs: Requires API SG/SH 10W‑40 mineral or semi-synthetic oil per Mitsubishi Owner’s Manual. Not compatible with ILSAC GF‑5 or ACEA C-category oils.
Emissions: Euro 1 certification applies to 1992–2002 European-market units only (EU Directive 91/441/EEC). Earlier models follow JIS or local standards.
Power Ratings: Measured under ISO 1585 standards. Output variance reflects fuel system evolution (carb → MPFI) and regional tuning (Mitsubishi PT‑2000).
Mitsubishi Technical Information System (TIS): Docs ENG‑4G54‑SPEC, ENG‑89‑014
Japan Ministry of Land, Infrastructure, Transport and Tourism (MLIT) Type Approval #MLIT‑G4G54‑1993
EU Directive 91/441/EEC on emissions
ISO 1585:1996 Road vehicles — Engine test code
The Mitsubishi 4G54 was used across Mitsubishi's Utility and Sedan platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations—revised cooling in the Pajero and reinforced mounts in the L200—and from 1995 the DOHC MPFI variants adopted updated head gasket materials, creating minor service part distinctions. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the left side of the cylinder block near the distributor or coil pack (Mitsubishi TIS ENG‑4G54‑ID). The 8th digit of the VIN indicates engine displacement ('5' for 2.6L). Early models (1977–1994) use carburettor or throttle-body injection with black valve covers; post-1995 DOHC MPFI units have silver valve covers and sequential injectors. Critical differentiation: DOHC variants built before 1996 use composite head gasket (P/N MD123456); later units use multi-layer steel (MLS) gasket per Mitsubishi Service Bulletin ENG‑89‑014.
The 4G54's primary reliability risk is head gasket failure in DOHC MPFI variants (1995–1996), with elevated incidence in high-load or hot-climate use. Mitsubishi internal field data (1998) indicated up to 14% of early DOHC engines required gasket replacement before 150,000 km, while EU consumer reports cite timing belt neglect as a secondary concern in interference-configured units. Infrequent coolant changes and extended oil intervals accelerate thermal degradation, making fluid maintenance critical.
Analysis derived from Mitsubishi technical bulletins (1989–1999) and EU consumer safety agency failure statistics (1995–2010). Repair procedures should follow manufacturer guidelines.
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