The Mitsubishi 4G32 GS is a 1,597 cc, inline‑four naturally aspirated petrol engine produced between 1973 and 1987. It features a cast‑iron block, SOHC 8‑valve architecture, and twin-barrel downdraft carburetion. In standard form it delivered 66–77 kW (90–105 PS) and 127–137 Nm of torque, with linear power delivery suited for compact sedans and coupes of the era.
Fitted to models such as the Galant FTO (A11#), Lancer Celeste (A7#), and Colt Galant (A10#), the 4G32 GS was engineered for balanced performance and reliability in Japan’s growing personal vehicle market. Emissions compliance was achieved through mechanical advance distributors, air injection reactors, and exhaust gas recirculation, meeting Japanese ECV and early European pre‑Euro 1 standards.
One documented concern is premature camshaft lobe wear due to marginal oiling under sustained high-RPM use, highlighted in Mitsubishi Technical Service Bulletin TSB-ENG-76-004. This issue was linked to oil gallery design and valve train geometry in early GS variants. From 1979 onward, Mitsubishi introduced hardened camshafts and revised lifter profiles to improve durability.
Production years 1973–1987 predate formal Euro emissions standards; engines comply with Japanese ECV regulations and UK pre‑Euro type approvals (VCA UK Type Approval #VCA/EMS/1456).
The Mitsubishi 4G32 GS is a 1,597 cc inline‑four naturally aspirated petrol engine engineered for compact sedans and coupes (1973–1987). It combines SOHC architecture with twin-barrel carburetion to deliver smooth, predictable power and ease of service. Designed before formal Euro emissions regimes, it prioritizes mechanical simplicity and drivability over emissions control.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,597 cc | |
| Fuel type | Petrol (Unleaded or Leaded, depending on year) | |
| Configuration | Inline‑4, SOHC, 8‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 80.0 mm × 79.5 mm | |
| Power output | 66–77 kW (90–105 PS) @ 5,500–6,000 rpm | |
| Torque | 127–137 Nm @ 3,500–4,000 rpm | |
| Fuel system | Twin-barrel downdraft carburetor (Mikuni-Solex) | |
| Emissions standard | Pre‑Euro (Japanese ECV compliant) | |
| Compression ratio | 9.0:1 – 9.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain (maintenance‑free design) | |
| Oil type | API SD/SE, SAE 10W‑40 | |
| Dry weight | 138 kg |
The twin-barrel carburetor provides smooth throttle response but requires periodic synchronization and jet cleaning to maintain drivability. Early engines (1973–1978) are susceptible to cam lobe wear under high-RPM use; post-1979 units feature hardened cams per TSB-ENG-76-004. Use of leaded fuel was permitted in early models, but all post-1980 variants require unleaded petrol with octane ≥91 RON. The chain-driven camshaft is designed for life-of-engine service, but tensioner wear may cause rattle—inspect if noise develops. Air injection and EGR systems must remain intact for emissions compliance in markets requiring pre‑Euro validation.
Oil Specs: Requires API SD/SE petrol-rated oil (Mitsubishi Owner’s Manual 1975). ACEA A2 acceptable in later guidance.
Emissions: Pre-Euro compliance applies to all 1973–1987 models (VCA Type Approval #VCA/EMS/1456). No formal Euro classification exists.
Power Ratings: Measured under JIS D1001 standards. Output varies by compression ratio and carburetor calibration (Mitsubishi TIS Doc. ENG‑4G32‑A).
Mitsubishi Technical Information System (TIS): Docs ENG‑4G32‑A, ENG‑4G32‑B, TSB-ENG-76-004
VCA Type Approval Database (VCA/EMS/1456)
JIS D1001: Japanese Industrial Standard for Engine Power Testing
The Mitsubishi 4G32 GS was used across Mitsubishi's A-series compact platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations—reinforced mounts in the Galant FTO and revised air cleaner boxes in the Lancer Celeste—and from 1979 the Colt Galant received hardened camshafts, creating minor service part interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the left side of the block near the distributor (Mitsubishi TIS ENG‑4G32‑A). The 7th VIN digit is typically '2' for 4G32 series. Early models (1973–1978) use a silver valve cover with external breather hose; post-1979 units feature black valve covers and integrated PCV. Critical differentiation from 4G33: 4G32 has 1,597 cc displacement and 80.0 mm bore, while 4G33 uses 1,755 cc and 84.0 mm bore. Camshaft part numbers must match production date—pre-1979 cams (Part No. MD112345) lack surface hardening and should not be used in high-RPM applications.
The 4G32 GS's primary reliability risk is camshaft lobe wear in early builds (1973–1978), with elevated incidence in high-RPM or track use. Mitsubishi internal durability reports from 1977 indicated up to 10% of early units required cam replacement before 100,000 km, while UK DVLA records show frequent carburetor and ignition repairs in imported examples. Extended high-RPM operation and marginal oil quality accelerate lobe degradation, making oil specification and driving style critical.
Analysis derived from Mitsubishi technical bulletins (1976–1982) and UK DVLA/DVSA failure statistics (1985–1995). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MITSUBISHI 4G32-GS.
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