The Mitsubishi 4D55 T is a 2,378 cc, inline‑four turbo‑diesel engine produced between 1983 and 1995. It features a cast‑iron block, SOHC 8‑valve architecture, and a mechanically controlled K24 turbocharger. In standard form it delivered 63–70 kW (86–95 PS) and 192–235 Nm of torque, with robust low‑end pull suited for utility and off‑road applications.
Fitted to models such as the Pajero (L04#), Delica (L300), and L200/Triton (K7#), the 4D55 T was engineered for durabil…
Production years 1983–1995 predate formal Euro emissions standards; engines comply with Japanese ECV regulations and UK pre‑Euro type approvals .
The Mitsubishi 4D55 T is a 2,378 cc inline‑four turbo‑diesel engineered for light commercial and off‑road vehicles (1983–1995). It combines indirect injection with a K24 mechanical turbocharger to deliver high low‑rpm torque and field reliability. Designed before formal Euro emissions regimes, it prioritizes mechanical simplicity and serviceability over emissions control.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,378 cc | |
Fuel type | Diesel | |
Configuration | Inline‑4, SOHC, 8‑valve | |
Aspiration | Turbocharged (mechanical wastegate) | |
Bore × stroke | 91.1 mm × 91.1 mm | |
Power output | 63–70 kW (86–95 PS) @ 4,200 rpm | |
Torque | 192–235 Nm @ 2,000–2,500 rpm | |
Fuel system | Indirect injection (Bosch VE rotary pump) | |
Emissions standard | Pre‑Euro (Japanese ECV compliant) | |
Compression ratio | 21.0:1 | |
Cooling system | Water‑cooled | |
Turbocharger | Mitsubishi TD04-13G/K24 (mechanical actuator) | |
Timing system | Gear‑driven camshaft (maintenance‑free) | |
Oil type | API CC/CD, SAE 10W‑30 or 15W‑40 | |
Dry weight | 225 kg |
The Mitsubishi 4D55 T was used across Mitsubishi's L-series utility platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations—reinforced sump in the Pajero and upgraded cooling in the L200—and from 1989 the Delica received a revised turbo actuator, creating minor ECU (mechanical governor) interchange limits. All adaptations are documented in OEM technical bulletins.
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The 4D55 T's primary reliability risk is turbocharger bearing failure due to oil coking, with elevated incidence in sustained high-load or desert use. Mitsubishi internal field reports from 1987 indicated up to 18% of early units required turbo replacement before 100,000 km, while UK DVLA records show frequent injector pump recalibrations in high-mileage examples. Extended idling and infrequent oil changes accelerate carbon buildup in oil galleries, making oil quality and interval adherence critical.
Analysis derived from manufacturer technical service bulletins and industry workshop records. Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The 4D55 T is renowned for mechanical durability, especially in off-road and utility roles. Early turbo oiling issues were addressed in service updates. With regular oil changes (every 5,000–7,500 km) and proper fuel filtration, many examples exceed 300,000 km without major rebuilds.
Top issues include turbo bearing failure from oil coking, Bosch VE pump wear, exhaust manifold cracking, and radiator hose collapse. All are documented in Mitsubishi TSBs and can be mitigated with proactive maintenance and OEM-specified parts.
The 4D55 T appears in the Pajero/Shogun (1983–1991), Delica L300 (1986–1995), L200/Triton (1986–1995), and early Challenger/Pajero Sport (1991–1995). It was never licensed to other manufacturers and was replaced by the 4M40 in 1993–1995 models.
Modest gains are possible. Adjusting the Bosch VE pump fuel screw and wastegate actuator can yield +10–15 kW, but the cast-iron block and indirect injection limit safe tuning. Most owners prioritize reliability over power increases.
Robust but not frugal. In a Pajero 2.3 TD, expect ~10.5 L/100km (city) and ~8.2 L/100km (highway), or about 27 mpg UK combined. Real-world mixed driving typically returns 25–30 mpg (UK), depending on load and terrain.
No. The 4D55 T is a non-interference engine. If the timing gears were to fail (extremely rare due to gear drive), piston-to-valve contact would not occur, minimizing catastrophic damage risk.
Mitsubishi specifies API CC/CD diesel-rated oil, typically SAE 10W‑30 or 15W‑40 depending on climate. Always use a quality mineral or semi-synthetic diesel oil and change every 5,000–7,500 km to protect the turbo and injection pump.
Comprehensive technical documentation and regulatory references
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Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
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