The Hyundai HD 65, HD 72, and HD 78 trucks were equipped with the D4AF inline 4-cylinder engine, which has a displacement of 3.6 liters and is water-cooled and directly injected with diesel fuel. It is intended to transport medium-ton loads (3.5 to 5 t). At 3400 rpm, the engine can produce up to 100 horsepower.
An annular piston and a cylinder head make up the engine’s combustion chamber; pinless fuel injectors are installed in the cylinder head. The fuel-air mixture is ignited by direct fuel injection into the combustion chamber, guaranteeing the piston’s working stroke. This engine’s piston is cast from an aluminum alloy and has an insert inside that gives the piston and cylinder liner the required space.
Specifications
| Manufacturer | Hyundai |
| Also called | D4AF |
| Configuration | 4-stroke, water-cooled and direct injection |
| Number of cylinders | 4 |
| Piston stroke, mm | 105 |
| Cylinder bore, mm | 104 |
| Displacement, cc | 3568 |
| Power output, hp | 100 |
| Torque output, Nm / rpm | 235 |
| Weight, kg | 320 |
The Hyundai D4AF engine is a type of overhead valve engine.
- Heat-resistant steel that has been surface-treated is used to make both inlet and outlet valves. Both valves have a 45-degree seat cone angle. An oil scraper cap on the valve stem controls the amount of lubricant on the sliding surfaces between the guide sleeve and the valve.
- An external and an internal valve spring with opposing turns are the two unevenly adjusted valve springs.
- The rocker shaft is a rounded, hollow rod with sealing caps on both ends. Inside, there is an oil channel. The pusher rod has a spherical or concave tip attached to the upper end and a steel ball tip attached to the lower end. Case hardened high is used to make both tips.
Cast iron makes up the D4AF engine’s engine block, which is a stiff structure with little stress and deformation. The cylinder block’s camshaft bearings have three camshaft bushings installed.
Explanation of D4AF marking
| D | Motor fuel – diesel |
| 4 | Number of cylinders – 4 |
| A | Engine Development Order |
| F | Engine Modifications |