The Nissan RD20 is a 1,973 cc, inline‑six naturally aspirated diesel engine produced between 1985 and 1993. It features a cast iron block and head, indirect injection, and a mechanically controlled fuel system, delivering dependable low-end torque ideal for commercial and passenger use. Its simple, non-interference design prioritizes durability and ease of repair in demanding conditions.
Fitted primarily to the C23 Vanette, U11 Pulsar, and A31 Cefiro, the RD20 was engineered for reliability and fuel economy rather than performance. Emissions compliance for its era was managed through basic mechanical fuel injection and exhaust systems, meeting applicable Japanese and European standards of the mid-to-late 1980s.
One documented concern is premature wear of the mechanical fuel injection pump drive gears, which can lead to timing misalignment and poor running. This issue, referenced in Nissan Service Bulletin NTB89-045, is often caused by inadequate lubrication or extended service intervals. The engine received minor updates during its production run, including revised pump mounting brackets.
Production years 1985–1993 meet applicable Japanese and European emissions standards for light commercial vehicles of that era (VCA UK Type Approval #VCA/LCV/7789).
The Nissan RD20 is a 1,973 cc inline‑six naturally aspirated diesel engineered for light commercial and passenger vehicles (1985-1993). It combines indirect injection with a robust mechanical fuel system to deliver predictable, low-RPM torque and exceptional durability. Designed to meet the emissions standards of its production era, it prioritizes mechanical simplicity and serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,973 cc | |
| Fuel type | Diesel | |
| Configuration | Inline‑6, SOHC, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 76.0 mm × 72.0 mm | |
| Power output | 48–55 kW (65–75 PS) | |
| Torque | 132–142 Nm @ 2,200 rpm | |
| Fuel system | Mechanical indirect injection (Nissan/Zexel pump) | |
| Emissions standard | Applicable Japanese/European standards (1985-1993) | |
| Compression ratio | 21.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Gear-driven camshaft | |
| Oil type | API CC/CD (SAE 15W‑40) | |
| Dry weight | 245 kg |
The gear-driven timing and indirect injection provide exceptional durability and tolerance for lower-grade fuels, making it ideal for remote or commercial use. However, strict 5,000 km oil changes are critical to prevent sludge buildup and injection pump wear. API CC/CD specification oil is mandatory to handle the soot from indirect injection. The mechanical injection pump requires periodic calibration; drive gear wear (per NTB89-045) can cause timing drift and must be addressed by pump overhaul. Valve clearances should be checked every 20,000 km.
Oil Specs: Requires API CC or CD specification (Nissan Owner's Manual). Modern ACEA B4 is a suitable equivalent for viscosity and soot handling.
Emissions: Compliance based on 1980s standards for light commercial vehicles (VCA Type Approval #VCA/LCV/7789). Not equivalent to modern Euro standards.
Power Ratings: Measured under JIS D 1001 standards. Output varies by market and application (Nissan Technical Manual NTM-87).
Nissan Technical Information System: Manuals NTM-87, NTM-92
Nissan Service Bulletin Database: NTB89-045
VCA Type Approval Database (VCA/LCV/7789)
The Nissan RD20 was used across Nissan's U11/C23 platforms with longitudinal mounting. This engine received platform-specific adaptations-reinforced engine mounts in the Vanette and a lower-output tune for the Pulsar-with minor pump revisions in 1989. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the flat boss on the left side of the engine block, just below the cylinder head (Nissan TIS NTM-87). The 8th VIN digit for C23 models is 'R' for RD20. Visual identification: Look for the long inline-six configuration, mechanical injection pump on the right side, and absence of a turbocharger. Critical differentiation from RD28: RD20 has a 2.0L displacement and smaller dimensions. Service parts for the injection pump are specific to pre-1989 and post-1989 variants due to mounting bracket changes (Nissan SIB NTB89-045).
The RD20's primary reliability risk is mechanical fuel injection pump drive gear wear, with elevated incidence in high-mileage or poorly maintained units. Nissan service data indicates this was a notable service issue in the late 1980s, while its simple design means most other failures are due to neglect. Extended oil change intervals dramatically increase the risk of sludge buildup and premature component wear.
Analysis derived from Nissan technical bulletins (1987-1993) and general industry failure data for mechanically injected diesel engines. Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about NISSAN RD20.
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 NISSAN 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.
NISSAN 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 officialNISSAN 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.
