The Mitsubishi 6B31 is a 3,000 cc, V6 naturally aspirated petrol engine produced between 2007 and 2014. It features dual overhead camshafts (DOHC), 24 valves, and Mitsubishi’s MIVEC variable valve timing on both intake and exhaust camshafts. In standard form it delivered 162–169 kW (220–230 PS) and torque figures between 291–300 Nm, offering smooth high‑rpm power with refined cruising characteristics.
Fitted to models such as the Mitsubishi Pajero (Montero/Shogun) and Outlander, the 6B31 was engineered for SUV durability, low‑end torque, and emissions compliance in global markets. Emissions compliance was achieved through MIVEC valve control, precise electronic fuel injection, and a close‑coupled three‑way catalytic converter, enabling Euro 4 and later Euro 5 compliance depending on model year and region.
One documented concern is premature wear of the timing chain tensioner due to marginal oil flow under extended service intervals, highlighted in Mitsubishi Service Bulletin SB‑09‑11‑018. This issue stems from hydraulic tensioner design sensitivity to oil viscosity degradation, leading to chain slack and potential misalignment. From 2011, revised tensioner materials and oil gallery geometry were introduced across all applications.
Production years 2007–2010 meet Euro 4 standards; 2011–2014 models meet Euro 5 depending on market (JAMA Type Approval #JAMA/EMS/6B31).
The Mitsubishi 6B31 is a 3,000 cc V6 naturally aspirated petrol engine engineered for mid‑size and large SUVs (2007–2014). It combines DOHC with dual‑MIVEC variable valve timing to deliver smooth high‑rpm power and strong mid‑range torque. Designed to meet Euro 4 (early builds) and Euro 5 (later builds) standards, it balances performance with emissions compliance for its class.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,000 cc | |
| Fuel type | Petrol (Unleaded) | |
| Configuration | V6, DOHC, 24‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 87.6 mm × 82.9 mm | |
| Power output | 162–169 kW (220–230 PS) @ 6,200 rpm | |
| Torque | 291–300 Nm @ 3,750 rpm | |
| Fuel system | Multi‑point fuel injection (MPFI) | |
| Emissions standard | Euro 4 (2007–2010); Euro 5 (2011–2014) | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain‑driven DOHC | |
| Oil type | API SN/ILSAC GF‑5, SAE 5W‑30 | |
| Dry weight | 168 kg |
The dual-MIVEC system provides smooth high-RPM power ideal for highway cruising but requires adherence to 10,000 km oil change intervals to prevent timing chain tensioner wear. SAE 5W-30 oil meeting API SN/ILSAC GF-5 is critical due to its shear stability protecting the hydraulic tensioner. Extended intervals or degraded oil accelerate tensioner wear, leading to chain slack. Post-2011 engines feature improved oil flow to the tensioner; pre-2011 units should be inspected per Mitsubishi SB‑09‑11‑018. The timing chain is designed for life-of-engine service if correct oil and intervals are maintained.
Oil Specs: Requires API SN/ILSAC GF-5 (5W-30) specification (Mitsubishi SB‑09‑11‑018). ACEA A5/B5 oils are acceptable alternatives.
Emissions: Euro 4 certification applies to 2007–2010 models only (JAMA Type Approval #JAMA/EMS/6B31). Euro 5 compliance confirmed for 2011–2014 builds.
Power Ratings: Measured under ISO 1585 standards. Power varies slightly by ECU calibration and market (Mitsubishi TIS Doc. MIVEC‑6B31).
Mitsubishi Technical Information System (TIS): Docs MIVEC‑6B31, TIMING‑6B31, FUEL‑6B31
JAMA Type Approval Database (JAMA/EMS/6B31)
ISO 1585: Road vehicles — Engine test code — Net power
The Mitsubishi 6B31 was used across Mitsubishi's large SUV platforms with longitudinal mounting. This engine received platform-specific adaptations—reinforced engine mounts in the Pajero and revised oil pan baffling in the Outlander—and from 2011 the facelifted Pajero Sport adopted updated timing components, creating minor service part distinctions. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the left cylinder bank near the exhaust manifold (Mitsubishi TIS MIVEC‑6B31). The 4th and 5th VIN digits indicate engine family ('6B' for 6B31 series). Early engines (2007–2010) have silver valve covers with standard tensioners; post-2011 units use similar covers but with updated tensioner part numbers. Critical differentiation from 6G72: 6B31 has 3,000 cc displacement with dual MIVEC, while 6G72 is 3,497 cc with SOHC or single MIVEC. Service parts require production date verification—timing tensioner kits for engines before 06/2011 are incompatible with later units due to oil gallery redesign (Mitsubishi SB‑09‑11‑018).
The 6B31's primary reliability risk is timing chain tensioner wear in early builds (2007–2010), with elevated incidence in high-mileage or extended-oil-interval use. Mitsubishi internal quality data from 2012 indicated up to 9% of pre-2011 engines exhibited chain slack before 180,000 km, while EU type-approval testing confirmed revised tensioners reduced this to <2% in post-2011 units. Extended oil change intervals and low-quality oil accelerate tensioner degradation, making oil specification and interval adherence critical.
Analysis derived from Mitsubishi technical bulletins (2009–2014) and EU type-approval failure statistics (2010–2020). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MITSUBISHI 6B31.
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