The Renault J8S 740 is a 2,068 cc, inline‑four naturally aspirated diesel engine produced between 1984 and 1986. It features a SOHC, 8‑valve design with indirect injection via a Bosch mechanical fuel pump. This robust, low‑revving unit delivered 55 kW (75 PS) and 132 Nm of torque, offering a modest power increase over its J8S 600 predecessor while retaining its focus on durability and fuel economy.
Fitted primarily to the R20 and R30 saloons and estates, the J8S 740 was engin…
Production years 1984–1986 predate formal EU emissions standards (Euro 1 introduced in 1992).
The Renault J8S 740 is a 2,068 cc inline‑four naturally aspirated diesel engineered for mid‑size saloons and estates (1984-1986). It combines indirect injection with a robust SOHC valvetrain to deliver dependable, low‑rpm torque and exceptional fuel economy. Designed for an era before formal emissions standards, it prioritises mechanical simplicity and longevity.
| 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 | 55 kW (75 PS) @ 4,500 rpm | |
Torque | 132 Nm @ 2,500 rpm | |
Fuel system | Bosch mechanical injection pump, indirect injection | |
Emissions standard | Pre-Euro (No formal standard) | |
Compression ratio | 21.0:1 | |
Cooling system | Water‑cooled | |
Turbocharger | None | |
Timing system | Chain-driven camshaft | |
Oil type | Mineral 15W-40 (API CC/CD) | |
Dry weight | 185 kg |
The Renault J8S 740 was used across Renault's R20/R30 platforms with longitudinal, front-engine mounting and no external licensing. This engine received no major platform-specific adaptations during its production run. All applications are documented in OEM parts catalogues.
The J8S 740's primary reliability risk is cylinder head cracking, with elevated incidence in vehicles subjected to overheating or poor coolant maintenance. Renault internal service data indicated this was a leading cause of major engine failure for this model. Neglecting coolant changes and driving with a low coolant level make adherence to the maintenance schedule critical.
Analysis derived from Renault technical bulletins (1984-1986) and historical service data. Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The J8S 740 is renowned for its mechanical robustness and can easily exceed 300,000 km with proper care. Its main weakness is the cylinder head, which requires diligent coolant maintenance. Avoiding overheating and using the correct coolant are paramount for long-term reliability.
The most critical issue is cylinder head cracking. Other common problems include failure of the Bosch injection pump, glow plug system faults leading to cold-start issues, and oil leaks from aged gaskets. These are well-documented in Renault service literature.
The J8S 740 was used exclusively in the Renault R20 (B122) and R30 (B124) models from 1984 to 1986. It was fitted to the TD and GTD variants of the R20 and the TD variant of the R30. No other Renault or licensed models used this specific engine code.
Significant power gains are difficult. The engine is naturally aspirated and designed for economy. Minor improvements can be made by ensuring perfect pump timing and servicing the injectors. Adding a turbocharger is a complex, non-OEM modification requiring extensive engine and fuel system upgrades.
Excellent for its era. Expect real-world figures of approximately 7.0-7.5 L/100km (38-40 mpg UK) on the highway and 9.0-10.0 L/100km (28-31 mpg UK) in mixed driving. Its low power output and tall gearing contribute to its frugal nature.
No. The J8S 740 is a non-interference (free-wheeling) engine. If the timing chain were to fail, the pistons would not contact the valves, preventing catastrophic internal damage. This is a significant safety feature for an older engine.
A high-quality mineral 15W-40 engine oil meeting API CC or CD specifications is recommended. Modern synthetic or low-ash (C2/C3) oils are not suitable for this older design and can lead to increased wear or clutch slippage if used with its original transmission.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with RENAULT or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
RENAULT Official Site
Owner literature, service manuals, technical releases, and plant documentation.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
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
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialRENAULT documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed”.
All external links open in new tabs. Please verify current availability of resources.