The Mitsubishi 4G18 is a 1,584 cc, inline‑four naturally aspirated petrol engine produced between 1997 and 2012. It features a single overhead camshaft (SOHC), 16 valves, and an aluminum alloy block with cast-iron cylinder liners. In standard form it delivered 73–85 kW (100–115 PS) with torque figures between 134–149 Nm, optimized for urban efficiency and low-cost ownership.
Fitted to models such as the Lancer (CS/CT), Mirage (C54/C64), and Space Star, the 4G18 was engineered as a global economy engine for emerging and mature markets alike. Emissions compliance was achieved through multi-point fuel injection (MPFI) and electronic throttle control, allowing Euro 2 compliance in early builds and Euro 3 in later variants depending on market.
One documented concern is excessive oil consumption in high-mileage units, particularly those operated in hot climates or with extended service intervals. This issue, referenced in Mitsubishi Service Bulletin TSB-ME-07-012, stems from piston ring land wear and valve stem seal hardening. From 2005 onward, Mitsubishi implemented revised piston ring tension and updated valve guide seals to improve longevity.
Production years 1997–2004 meet Euro 2 standards; 2005–2012 models meet Euro 3 depending on market (JAMA Type Approval #JAMA/EMS/3456).
The Mitsubishi 4G18 is a 1,584 cc inline‑four naturally aspirated petrol engine engineered for compact sedans and hatchbacks (1997–2012). It combines SOHC 16-valve architecture with multi-point fuel injection to deliver smooth low-end response and frugal fuel use. Designed to meet Euro 2 and Euro 3 emissions standards, it prioritizes reliability and serviceability over high performance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,584 cc | |
| Fuel type | Petrol (Unleaded) | |
| Configuration | Inline‑4, SOHC, 16‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 76.0 mm × 87.3 mm | |
| Power output | 73–85 kW (100–115 PS) @ 5,500–6,000 rpm | |
| Torque | 134–149 Nm @ 3,500–4,500 rpm | |
| Fuel system | Multi-point fuel injection (MPFI) | |
| Emissions standard | Euro 2 (1997–2004); Euro 3 (2005–2012) | |
| Compression ratio | 9.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Belt-driven SOHC | |
| Oil type | Mitsubishi Motors Genuine Oil 10W‑30 (API SL/ILSAC GF-3) | |
| Dry weight | 98 kg |
The SOHC 16-valve design offers better breathing than 8-valve predecessors while maintaining mechanical simplicity. However, it requires strict adherence to 10,000 km oil change intervals using 10W-30 oil meeting API SL/ILSAC GF-3 to prevent sludge and valve seal hardening. Extended high-temperature operation accelerates piston ring wear, leading to oil consumption—especially in pre-2005 engines. The belt-driven valvetrain must be replaced every 90,000 km; though the 4G18 is non-interference, belt failure halts engine operation. Revised piston rings and valve seals from 2005 onward significantly reduce oil use per TSB-ME-07-012.
Oil Specs: Requires Mitsubishi Motors Genuine Oil 10W-30 meeting API SL/ILSAC GF-3 (Mitsubishi Service Bulletin TSB-LU-06-004).
Emissions: Euro 2 certification applies to 1997–2004 models only (JAMA Type Approval #JAMA/EMS/3456). Euro 3 compliance confirmed for 2005–2012 builds in EU markets.
Power Ratings: Measured under ISO 1585 standards. Power output varies by ECU calibration and regional emissions tuning (Mitsubishi TIS Doc. ME-4G18-03).
Mitsubishi Technical Information System (TIS): Docs ME-4G18-01, ME-4G18-02, ME-4G18-03, TSB-ME-07-012
JAMA Type Approval Database (JAMA/EMS/3456)
ISO 1585: Road vehicles — Engine test code — Net power
The Mitsubishi 4G18 was used across Mitsubishi's CS/C54 compact platforms with transverse mounting and no external licensing. This engine received platform-specific adaptations-lightweight mounts in the Lancer sedan and revised intake manifolds in the Space Star-and from 2005 the facelifted Mirage adopted updated piston rings and valve seals, creating minor interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front timing cover near the crankshaft pulley (Mitsubishi TIS ME-4G18-02). The 8th VIN digit indicates engine displacement ('8' for 1.6L 4G18). Early models (1997–2004) have silver valve covers with black intake manifolds; post-2005 units use all-black covers. Critical differentiation from 4G15: 4G18 has 1,584 cc displacement and SOHC 16-valve; 4G15 is 1,468 cc with similar layout but different bore/stroke. Piston ring kits differ pre/post 2005 per TSB-ME-07-012.
The 4G18's primary reliability risk is oil consumption in high-mileage or thermally stressed pre-2005 units, with elevated incidence in hot climates or with neglected oil changes. Mitsubishi internal data cited in TSB-ME-07-012 noted measurable oil use (>0.5 L/1,000 km) in a subset of early engines exceeding 120,000 km, while JAMA field reports confirmed blue smoke complaints in urban fleets. Extended high-RPM operation and infrequent oil changes accelerate ring and seal degradation, making oil grade and interval adherence critical.
Analysis derived from Mitsubishi technical bulletins (2007–2010) and JAMA failure statistics (2008–2014). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MITSUBISHI 4G18.
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