The Renault J8S 706 is a 2,068 cc, inline‑four naturally aspirated diesel engine produced between 1982 and 1986. It features a SOHC, 8‑valve design with indirect injection via pre‑combustion chambers, delivering modest outputs for its era. This mechanically simple engine prioritised durability and ease of maintenance, making it suitable for commercial and fleet applications.
Fitted primarily to the Renault 20 and 30 (R20/R30) models, the J8S 706 was engineered for steady, economical cruising and reliable service under load. Emissions compliance for its production period was managed through basic engine tuning and combustion chamber design, aligning with pre‑Euro standards prevalent before 1992.
One documented characteristic is susceptibility to cylinder head cracking, particularly between valve seats, often linked to overheating events or coolant system neglect. This issue, referenced in Renault's internal technical service notes, underscores the importance of maintaining optimal engine temperature. The J8S series was succeeded by more advanced direct-injection diesel engines.
Production years 1982–1986 predate formal Euro emissions standards (EU Directive 91/441/EEC). Compliance was governed by national regulations (e.g., French homologation).
The Renault J8S 706 is a 2,068 cc inline‑four naturally aspirated diesel engineered for mid‑size sedans and estates (1982-1986). It combines indirect injection with a single overhead camshaft to deliver predictable, low‑stress performance. Designed for reliability in an era before stringent emissions mandates, it prioritises mechanical simplicity and serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,068 cc | |
| Fuel type | Diesel | |
| Configuration | Inline‑4, SOHC, 8‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 88.0 mm × 85.0 mm | |
| Power output | 44 kW (60 PS) | |
| Torque | 123 Nm @ 2,500 rpm | |
| Fuel system | Indirect injection (Bosch PES6A pump) | |
| Emissions standard | Pre‑Euro (National Homologation) | |
| Compression ratio | 22.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain‑driven camshaft | |
| Oil type | Mineral 15W‑40 (CC/CD spec) | |
| Dry weight | Not specified in available OEM docs |
The indirect injection system provides smooth, albeit slow, combustion ideal for steady cruising but results in higher fuel consumption compared to modern diesels. Regular coolant system maintenance is critical to prevent cylinder head cracking. Using the specified mineral oil (15W-40) is essential for older bearing and seal materials. The Bosch injection pump requires precise timing adjustment during service. Pre-heating glow plugs are vital for reliable cold starts.
Oil Specs: Requires mineral 15W-40 meeting API CC/CD or equivalent (Renault TM 77 11 068 000). Modern low-ash oils are not recommended.
Emissions: Pre-Euro certification; governed by national homologation standards (e.g., French RTAC). No formal EU type approval exists for this era.
Power Ratings: Measured under DIN 70020 standards. Output is net power at the flywheel (Renault TM 77 11 068 000).
Renault Technical Manual 77 11 068 000
Renault EPC (Electronic Parts Catalogue) - Engine Code J8S
EU Directive 91/441/EEC (Historical Reference for Emissions)
The Renault J8S 706 was used across Renault's R20/R30 platform with longitudinal mounting and was not licensed to other manufacturers. This engine received minor platform-specific adaptations-primarily related to ancillary mounting and exhaust routing-and no significant facelift revisions occurred during its production run. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on a flat boss on the cylinder block, typically near the injection pump or on the front face (Renault TM 77 11 068 000). The full code "J8S 706" should be clearly visible. Visually, it is identifiable by its cast-iron block, aluminium cylinder head, and the prominent Bosch PES6A inline injection pump mounted longitudinally on the engine's right side. Differentiate from petrol R20/R30 engines by the presence of glow plugs and the diesel injection pump.
The J8S 706's primary reliability risk is cylinder head cracking, often triggered by overheating. While robust mechanically, neglect of the cooling system is the most common cause of major failure. Extended operation at high temperatures or with low coolant levels significantly increases the risk of head damage.
Analysis derived from Renault technical manuals (1980s) and aggregated European workshop failure reports (1985-1995). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about RENAULT J8S-706.
Comprehensive technical documentation and regulatory references
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RENAULT Official Site
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EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
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DVLA: Engine Changes & MoT
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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
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