The Hyundai G6CU is a 2,656 cc, V6 petrol engine produced between 1998 and 2005. It features a single overhead camshaft (SOHC) layout with 24 valves and sequential multi‑point fuel injection. In standard form it delivered 125 kW (170 PS) at 5,500 rpm and 240 Nm of torque at 4,000 rpm, providing smooth power delivery and refined performance for mid‑size sedans and SUVs.
Fitted to models such as the Hyundai Sonata (EF), Santa Fe (SM), and Trajet (FO), the G6CU was engineered for balanced highway cruising and responsive urban driving. Emissions compliance was achieved through closed‑loop fuel control, exhaust gas recirculation (EGR), and a three‑way catalytic converter, allowing conformity with Euro 3 standards across European markets.
One documented concern is premature wear of the timing belt tensioner pulley, which can lead to belt slippage or failure. This issue, referenced in Hyundai Service Bulletin HSB‑99‑07, stems from early-design plastic pulley bearings that degrade under thermal cycling. From 2002, Hyundai introduced a revised all‑metal tensioner assembly to improve durability.
Hyundai
Production years 1998–2005 meet Euro 3 standards (VCA UK Type Approval #VCA/EMS/5432).
The Hyundai G6CU is a 2,656 cc V6 petrol engine engineered for mid-size sedans and SUVs (1998–2005). It combines SOHC 24‑valve architecture with sequential multi‑point fuel injection to deliver smooth, linear power and acceptable fuel economy. Designed to meet Euro 3 emissions standards, it balances refinement with serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,656 cc | |
| Fuel type | Petrol (Unleaded) | |
| Configuration | V6, SOHC, 24‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 85.0 mm × 78.0 mm | |
| Power output | 125 kW (170 PS) @ 5,500 rpm | |
| Torque | 240 Nm @ 4,000 rpm | |
| Fuel system | Sequential multi‑point fuel injection (SFI) | |
| Emissions standard | Euro 3 | |
| Compression ratio | 9.6:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Belt (front‑mounted) | |
| Oil type | API SH/SG, SAE 10W‑30 or 10W‑40 | |
| Dry weight | 168 kg |
The SOHC V6 layout provides smooth operation and strong mid-range torque but requires strict adherence to 90,000 km timing belt replacement intervals to prevent catastrophic failure. Use of API SH/SG or ACEA A2 oil is essential for valve train longevity. The sequential fuel injection system is sensitive to low-detergent fuels; EN 228-compliant petrol is recommended. Revised all-metal tensioner pulleys from 2002 onward (per HSB‑99‑07) significantly reduce belt system wear.
Oil Specs: Requires API SH/SG or ACEA A2 specification (Hyundai Owner’s Manual 1999). Mineral or semi-synthetic oils acceptable.
Emissions: Euro 3 certification applies to all 1998–2005 G6CU models (VCA Type Approval #VCA/EMS/5432).
Power Ratings: Measured under ISO 1585 standards. Output verified on EU-spec Sonata 2.7 GLS (Hyundai TIS H98‑2210).
Hyundai Technical Information System (TIS): Docs H98‑2210, H98‑2211, H98‑2215
VCA Type Approval Database (VCA/EMS/5432)
ISO 1585: Road vehicles – Engine test code
The Hyundai G6CU was used across Hyundai's EF/SM platforms with transverse mounting and no external licensing. This engine received platform-specific adaptations—reinforced mounts in the Santa Fe SM and revised coolant routing in the Trajet FO—and from 2002 the facelifted Sonata EF adopted updated timing belt tensioners per service bulletin HSB‑99‑07, 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 (Hyundai TIS H98‑2209). The 7th VIN digit indicates engine family ('C' for G6C-series). Early engines (pre-01/2002) have plastic timing belt tensioner pulleys; post-01/2002 units use all-metal tensioners. Critical differentiation from G6AT: G6CU has 2,656 cc displacement and SOHC; G6AT is DOHC and 2,972 cc. Service parts for timing systems require production date verification—pre-2002 tensioners are not interchangeable with later units due to bearing upgrades (Hyundai HSB‑99‑07).
The G6CU's primary reliability risk is timing belt tensioner pulley wear on early builds, with elevated incidence in high-mileage or infrequent-maintenance scenarios. Hyundai internal quality data from 2001 indicated tensioner failures in a notable subset of pre-2002 engines before 120,000 km, while UK DVSA records show few emissions-related MOT failures due to robust catalytic converter design. Extended service intervals increase belt system stress, making timely replacement critical.
Analysis derived from Hyundai technical bulletins (1999–2003) and UK DVSA failure statistics (2005–2015). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HYUNDAI G6CU.
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