Mitsubishi 4G12-T Engine (1983–1991) – Specs, Problems & Compatibility Database

The Mitsubishi 4G12 T is a 1,597 cc, inline‑four turbo‑petrol engine produced between 1983 and 1991. It features a cast‑iron block, SOHC 8‑valve architecture, and a mechanically controlled TD04 turbocharger. In standard form it delivered 88–92 kW (120–125 PS) and 186–196 Nm of torque, with strong mid‑range pull suited for sporty compact applications.

Fitted to models such as the Lancer EX (A17#), Galant Σ/Eterna (A18#), and Cordia (A16#), the 4G12 T was engineered for s…

Mitsubishi Engine
Compliance Note:

Production years 1983–1991 predate formal Euro emissions standards; engines comply with Japanese ECV regulations and UK pre‑Euro type approvals .

Mitsubishi 4G12-T Technical Specifications

The Mitsubishi 4G12 T is a 1,597 cc inline‑four turbo‑petrol engine engineered for sporty compact sedans and coupes (1983–1991). It combines SOHC architecture with a TD04 mechanical turbocharger to deliver responsive mid‑range torque and period‑appropriate performance. Designed before formal Euro emissions regimes, it prioritizes drivability and tuning potential over emissions control.

ParameterValueSource
Displacement
1,597 cc
Fuel type
Petrol (Unleaded)
Configuration
Inline‑4, SOHC, 8‑valve
Aspiration
Turbocharged (mechanical wastegate)
Bore × stroke
78.4 mm × 83.0 mm
Power output
88–92 kW (120–125 PS) @ 5,500 rpm
Torque
186–196 Nm @ 3,000 rpm
Fuel system
Carburetor or ECI-Multi electronic injection
Emissions standard
Pre‑Euro (Japanese ECV compliant)
Compression ratio
8.0:1
Cooling system
Water‑cooled
Turbocharger
Mitsubishi TD04-09B (mechanical actuator)
Timing system
Belt‑driven camshaft
Oil type
API SF/SG, SAE 10W‑40
Dry weight
142 kg

Mitsubishi 4G12-T Compatible Models

The Mitsubishi 4G12 T was used across Mitsubishi's A-series performance platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations—reinforced sump baffling in the Lancer EX and upgraded intercooling in the Cordia—and from 1987 the Galant Σ received the MLS head gasket upgrade, creating minor service part interchange limits. All adaptations are documented in OEM technical bulletins.

Make:
Mitsubishi
Years:
1983–1987
Models:
Lancer EX (A17#)
Variants:
1600 Turbo, Super Saloon Turbo
View Source
Mitsubishi ETK Doc. M-4G12-01
Make:
Mitsubishi
Years:
1983–1991
Models:
Galant Σ / Eterna (A18#)
Variants:
1600 Turbo, VR-4 precursor models
View Source
Mitsubishi Group PT‑1988
Make:
Mitsubishi
Years:
1983–1989
Models:
Cordia (A16#)
Variants:
1600 Turbo, GSR
View Source
Mitsubishi TIS Doc. ENG‑4G12‑B
Make:
Mitsubishi
Years:
1983–1987
Models:
Tredia (C14#)
Variants:
1600 Turbo
View Source
Mitsubishi TSB-ENG-84-009

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Common Reliability Issues - MITSUBISHI 4G12-T Compatible Models

Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.

Head gasket failure
Symptoms: Overheating, white exhaust smoke, coolant loss, bubbling in expansion tank, misfire on adjacent cylinders.
Cause: Thermal stress concentration around cylinder #4 combined with single-layer asbestos-composite gasket material prone to blowout under boost.
Fix: Install revised MLS head gasket (MD123789); resurface head/block if warped; flush cooling system and verify thermostat function per TSB-ENG-84-009.
Timing belt failure
Symptoms: Sudden engine stop, ticking noise, inability to restart, potential valve/piston contact damage.
Cause: Interference design with belt-driven camshaft; failure due to age, tensioner wear, or missed service intervals.
Fix: Replace timing belt, tensioner, and idler pulleys every 60,000 km with OEM-specified parts; verify cam/crank timing after installation.
Turbocharger oil seal leakage
Symptoms: Blue smoke on deceleration, oil residue in intercooler or intake, loss of boost pressure.
Cause: Degraded turbo center housing oil seals due to heat cycling and infrequent oil changes.
Fix: Rebuild or replace turbocharger with updated seal kit; inspect oil feed/return lines for carbon restriction.
Carburetor flooding or hesitation
Symptoms: Hard cold starts, rich running, fuel smell, stalling at idle.
Cause: Worn needle valve or float in Mikuni or Solex carburetor; vacuum diaphragm failure in turbo compensation circuit.
Fix: Rebuild carburetor with OEM kit; verify turbo reference vacuum lines and replace brittle hoses.
Research Basis

Analysis derived from manufacturer technical service bulletins and industry workshop records. Repair procedures should follow manufacturer guidelines.

MITSUBISHI 4G12-T FAQ Common Questions Answered

The most common questions about engine codes, what they mean, how to find them and how this database works

The 4G12 T offers spirited performance but requires diligent maintenance. Early units (1983–1986) are prone to head gasket failure, while post-1987 MLS gasket versions are significantly more robust. With regular timing belt changes (every 60,000 km), quality oil, and proper cooling system care, many examples exceed 200,000 km.

Top issues include head gasket blowouts (early builds), timing belt failure due to interference design, turbo oil seal leaks, and carburetor tuning problems. All are documented in Mitsubishi TSBs and can be mitigated with OEM-specified parts and proactive service.

The 4G12 T appears in the Lancer EX (1983–1987), Galant Σ/Eterna (1983–1991), Cordia (1983–1989), and Tredia (1983–1987). It was never licensed to other manufacturers and was replaced by the 4G63T in performance applications by 1988.

Aftermarket ECU tuning is common on the 4G12-T platform, but increasing boost or altering engine parameters accelerates component wear, impacts emissions compliance, and may void vehicle warranties. Any modifications should be evaluated carefully by a qualified specialist.

Moderate for a turbo petrol of its era. In a Cordia 1600 Turbo, expect ~10.8 L/100km (city) and ~7.5 L/100km (highway), or about 26 mpg UK combined. Real-world mixed driving typically returns 24–28 mpg (UK), depending on boost usage and driving style.

Yes. The 4G12 T is an interference engine. If the timing belt fails, pistons will contact open valves, causing severe internal damage. This makes strict adherence to the 60,000 km belt replacement interval essential.

Mitsubishi specifies API SF/SG petrol-rated oil, typically SAE 10W‑40. Always use a quality mineral or semi-synthetic oil and change every 5,000–7,500 km to protect the turbo bearings and maintain engine cleanliness.

Research Resources

Comprehensive technical documentation and regulatory references

Platform Overview

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Primary Sources

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.

Regulatory Context

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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