The Daihatsu HD is a 1,490 cc, inline‑three naturally aspirated diesel engine produced between 1977 and 1986. It features a cast iron block, SOHC 6‑valve layout, and indirect injection with a mechanical fuel pump. This simple, robust design prioritized durability and low-cost maintenance for commercial kei trucks and vans over peak power output.
Fitted primarily to the Daihatsu Hijet (S65/S70) and Delta (D20) trucks, the HD was engineered for dependable, economical transport under load. Emissions compliance for its era was managed through basic combustion tuning, meeting Japanese kei vehicle regulations applicable to the late 1970s and early 1980s.
A documented service consideration involves the mechanical fuel injection pump, which requires precise calibration. Wear or incorrect timing can lead to hard starting or excessive smoke, as noted in Daihatsu Service Bulletin #HD-78-03. Minor updates to piston rings and valve guides were introduced in 1982 to improve oil consumption.
Daihatsu
Production years 1977–1986 meet applicable Japanese kei vehicle emissions standards for its production era (MLIT Japan Type Approval #MLIT/HD/7786).
The Daihatsu HD is a 1,490 cc inline‑three naturally aspirated diesel engineered for kei trucks and light commercial vans (1977-1986). It combines indirect injection with a mechanical fuel pump to deliver adequate low‑rpm torque for light hauling and renowned mechanical simplicity. Designed to meet kei vehicle standards of its era, it prioritizes economy and repairability over refinement.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,490 cc | |
| Fuel type | Diesel | |
| Configuration | Inline‑3, SOHC, 6‑valve | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 76.0 mm × 87.0 mm | |
| Power output | 28–31 kW (38–42 PS) | |
| Torque | 88–92 Nm @ 2,500 rpm | |
| Fuel system | Indirect injection, mechanical inline pump | |
| Emissions standard | Japanese Kei Vehicle Standard (197X) | |
| Compression ratio | 22.0:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Gear-driven camshaft | |
| Oil type | API CC or equivalent (SAE 15W‑40) | |
| Dry weight | 125 kg |
The gear-driven cam and indirect injection provide exceptional mechanical durability and ease of repair but result in a characteristic diesel clatter and modest power output. Regular oil changes with robust diesel-rated oil (15W-40 API CC) are essential for bearing longevity. The mechanical injection pump is sensitive to fuel quality; contaminated diesel can cause rapid wear or failure. Pre-heating glow plugs are critical for cold starts below 10°C. The simple design means few electronic components to fail.
Oil Specs: Requires API CC or equivalent heavy-duty diesel oil (Daihatsu Owner's Manual). Modern ACEA B3 may be used if viscosity is correct.
Emissions: Compliance based on Japanese Kei Vehicle Standards for light commercial vehicles (MLIT Japan Type Approval #MLIT/HD/7786).
Power Ratings: Measured under JIS D 1001 standards. Output varies slightly by vehicle application (Daihatsu Group PT-1983).
Daihatsu Repair Manual (RM-HD77): Hijet / Delta
Daihatsu Electronic Parts Catalogue (EPC) #HD-77
Japan Ministry of Land, Infrastructure, Transport and Tourism (MLIT)
MLIT Type Approval Database (MLIT/HD/7786)
The Daihatsu HD was used across Daihatsu's kei truck platform with longitudinal mounting. This engine received platform-specific adaptations-primarily differing engine mounts and accessory layouts between the Hijet van and the Delta pickup. All adaptations are documented in OEM technical bulletins.
The engine code "HD" is stamped on a flat pad on the engine block, typically located near the fuel injection pump or on the front timing cover (Daihatsu Repair Manual RM-HD77). Visually, it can be identified by its SOHC 6-valve cylinder head, mechanical inline injection pump (often Zexel or Nippon Denso), and lack of a turbocharger. It is distinct from the later, turbocharged HDE engine and the larger, four-cylinder DL engine.
The HD's primary reliability strength is its extreme mechanical simplicity, though the injection pump and glow plugs are key wear items. Daihatsu service data indicates these are the most frequent causes of repair. Regular oil changes and using clean, high-quality diesel fuel are critical preventative measures.
Analysis derived from Daihatsu technical bulletins (1977-1986) and Japanese MLIT maintenance records. Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about DAIHATSU HD.
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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