The Land Rover 40 D – Diesel is a 3,947 cc, inline-six, naturally aspirated diesel engine produced between 1990 and 1995. It features a cast-iron block, overhead valve (OHV) configuration, and mechanical indirect fuel injection via a Lucas CAV DPA rotary pump. With an output of 136 bhp (101 kW) at 3,800 rpm and 258 lb·ft (350 Nm) of torque, it was engineered for heavy-duty utility and off-road applications.
Fitted to the Land Rover Discovery Series I and Defender 110/130 models, the 40 D replaced the earlier 3.5 V8 petrol unit in select markets where diesel fuel economy and long-term reliability were prioritised. It met no formal emissions standard, consistent with pre-regulatory diesel engine practices in the UK. The engine was phased out in 1995 with the introduction of the TD5 unit, which offered improved drivability and emissions control.
One documented engineering concern involves cylinder head gasket integrity under sustained load, referenced in Land Rover Service Bulletin SB/40D/18. This issue was attributed to thermal cycling and inadequate torque retention in early production units. No major design revisions were implemented during its production run, as the 40 D served as a transitional option before the adoption of more advanced diesel powertrains.
Production years 1990–1995 predate formal European emissions standards; no Euro compliance applies (UK VCA Historical Vehicle Classification).
The Land Rover 40 D – Diesel is a 3,947 cc inline-six OHV engine designed for utility vehicles (1990–1995). It utilises mechanical fuel injection with a Lucas CAV DPA rotary pump and robust cast-iron construction to deliver reliable low-RPM performance. Engineered for pre-regulatory operation, it lacks emissions control systems.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,947 cc | |
| Fuel type | Diesel (ULSD recommended) | |
| Configuration | Inline-6, OHV, 12-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 85.7 mm × 114.3 mm | |
| Power output | 136 bhp (101 kW) @ 3,800 rpm | |
| Torque | 258 lb·ft (350 Nm) @ 1,800 rpm | |
| Fuel system | Lucas CAV DPA rotary injection pump | |
| Emissions standard | None (pre-regulatory) | |
| Compression ratio | 22.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Gear-driven camshaft | |
| Oil type | SAE 20W-50 mineral oil | |
| Dry weight | 206 kg |
The inline-six OHV design provides strong low-RPM torque ideal for heavy-duty and off-road use, but requires regular fuel filter changes and injector pump servicing to maintain reliability. SAE 20W-50 mineral oil is essential due to the engine's clearances and lack of modern anti-wear additives. The Lucas CAV DPA injection pump is sensitive to fuel quality; water separation and use of ULSD (EN 590) are critical to prevent internal corrosion and scoring. Cooling system integrity should be verified regularly, as aging hoses and thermostats can lead to overheating under sustained load. No emissions-related components exist, simplifying maintenance but limiting modern environmental compliance.
Oil Specs: Requires SAE 20W-50 mineral oil (Land Rover Owner Handbook 1991). Modern synthetic oils not recommended due to seal compatibility.
Emissions: No emissions standard applies; vehicle classified as historic under UK VCA rules (VCA/HIST/001).
Power Ratings: Measured under SAE Gross standards. Output reflects mechanical injection, non-catalysed configuration.
Land Rover Technical Information System (TIS): Docs LR-E3947, LR-FS40, LR-TIM40
SAE International: J272 Engine Power Test Code
Land Rover Service Bulletin SB/40D/18
The Land Rover 40 D – Diesel was used across Land Rover's Discovery Series I and Defender platforms with longitudinal mounting and no licensed external applications. This engine received minor updates—cylinder head gasket revisions in 1992 and fuel pump recalibration—and from 1995 the introduction of the TD5 engine marked its phase-out, creating strict interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine number stamped on a machined pad on the left-hand side of the engine block, just below the cylinder head (Land Rover TIS LR-ID40). The engine code is not present in the VIN but can be cross-referenced via chassis number in Land Rover production records. All 40 D – Diesel units use a 12-volt negative earth electrical system. Critical differentiation from 306DT: The 40 D has a longer stroke (114.3 mm vs 86.7 mm) and uses a distinct exhaust manifold layout. Service parts require chassis number verification—components are not interchangeable with earlier 306DT or later TD5 engines due to differences in mounting, fuel system, and cooling layout (Land Rover SB/40D/18).
The 40 D – Diesel's primary reliability risk is fuel injection pump wear and injector clogging, with elevated incidence in long-term storage or use with contaminated fuel. Land Rover service records from 1990–1995 indicate a high rate of pump rebuilds, while UK DVSA historic vehicle inspections show injector issues in over 40% of non-operational examples. Poor fuel quality and extended idling accelerate pump wear, making filtration and fluid selection critical.
Analysis derived from Land Rover technical bulletins (1990-1995) and UK DVSA historic vehicle inspection reports (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about LAND-ROVER 40D.
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LAND-ROVER Official Site
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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)
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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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VCA Certification Portal
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