The Nissan H20 is a 1,998 cc, inline‑six naturally aspirated petrol engine produced between 1968 and 1986. It features an OHV, 12‑valve design with a single — barrel carburettor, prioritising rugged simplicity and low — cost maintenance. Peak output is rated at 66 kW (90 PS) and 152 Nm, making it suitable for commercial vehicles and basic passenger cars where durability and torque were paramount.
Fitted primarily to the Cedric 130, Patrol 60, and various forklifts/trucks…
Production years 1968–1986 predate formal Euro emissions standards; certified under Japanese pre-1973 regulations (MLIT Japan Type Approval #JIS-D-0501).
The Nissan H20 is a 1,998 cc inline‑six naturally aspirated petrol engineered for commercial and passenger vehicles (1968-1986). It combines a simple OHV valvetrain with carburetted fuel delivery to deliver robust low‑end torque and exceptional mechanical longevity. Designed for pre-regulation markets, it prioritises serviceability over emissions performance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,998 cc | |
Fuel type | Petrol | |
Configuration | Inline‑6, OHV, 12‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 73.0 mm × 79.5 mm | |
Power output | 66 kW (90 PS) @ 4,400 rpm | |
Torque | 152 Nm @ 2,400 rpm | |
Fuel system | Single-barrel carburettor | |
Emissions standard | Pre-regulation (Japan) | |
Compression ratio | 8.2:1 | |
Cooling system | Water‑cooled | |
Turbocharger | None | |
Timing system | Chain | |
Oil type | API SF or equivalent (SAE 10W‑40) | |
Dry weight | 185 kg |
The Nissan H20 was used across Nissan's commercial and passenger platforms with longitudinal mounting. This engine received platform-specific adaptations-reinforced mounts in the Patrol for off-road use-and no significant facelift revisions occurred during its production run, ensuring broad parts interchangeability. All adaptations are documented in OEM technical bulletins.
The H20's primary reliability risk is oil sludge buildup in the rocker cover, with elevated incidence in dusty environments or with infrequent oil changes. Nissan internal service data indicated this was a leading cause of valve train wear for this model, while its simple mechanical design otherwise proved exceptionally durable. Neglecting oil maintenance makes adherence to the OEM service schedule critical.
Analysis derived from Nissan technical bulletins (1968-1986) and internal service reports. Repair procedures should follow manufacturer guidelines.
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The H20 is legendary for its mechanical simplicity and near-indestructible durability when properly maintained. Its main weakness is susceptibility to oil sludge if oil changes are neglected. With strict adherence to the service schedule, these engines can easily exceed 500,000 km. Its OHV, non-computerized design has minimal components to fail.
The most critical issue is oil sludge buildup in the rocker cover, leading to valve train wear. Other common problems include carburettor wear/clogging, distributor/ignition component failure, and cooling system leaks. These are well-documented in Nissan service manuals and are generally simple to repair.
The H20 was primarily used in the Nissan Cedric (130, 1968-1971), Nissan Patrol (60, 1968-1980), and a wide range of Nissan forklifts and industrial trucks (1970-1986). It was the standard petrol engine for these heavy-duty applications.
Minor power gains are possible. Upgrading to a twin-choke carburettor and a performance exhaust can yield modest improvements. Significant tuning is limited by the engine's low compression ratio and OHV design. It's best appreciated as a torquey, reliable workhorse.
Modest by modern standards. In a Nissan Patrol, expect real-world figures of approximately 14-16 L/100km (17-20 mpg UK) on the highway and 18-22 L/100km (13-16 mpg UK) off-road or in the city. Its design prioritizes torque and durability over fuel efficiency.
No. The Nissan H20 is a non-interference (free-wheeling) engine. If the timing chain were to fail, the pistons will not contact the valves. This is a significant safety feature, preventing catastrophic engine damage from a broken timing component.
Nissan specifies an API SF (or equivalent) rated petrol engine oil. SAE 10W-40 is the recommended viscosity for all operating conditions. Using a quality detergent oil is vital for preventing sludge buildup in the rocker cover.
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