The Nissan SD23 is a 2.3 l (2,289 cc) inline-four, water-cooled diesel engine from Nissan SD family, manufactured by the Nissan Diesel Motor Co.
The Nissan SD23 is a bored-out version of the SD20 diesel engine. The compression ratio is 20.5:1. The cylinder bore is 89.0 mm (3.50 in) and the piston stroke is 92.0 mm (3.62 in).
The Nissan SD23 engine produced 73.4 PS (54.0 KW; 72.4 HP) at 4,300 rpm of horsepower.
The SD23 engine was equipped with Kiki-Bosch in-line or VE fuel injection pump. In Europe and Australia, the SD23 engine was used in the Nissan / Datsun 720 with Kiki-Bosch VE fuel injection pump, for other markets used an in-line pump.
The breakdown of the engine code is as follows:
- SD – Engine Family
- 23 – 2.3 Liter Displacement
General information
| Engine Specifications | |
| Engine code | SD23 |
| Layout | Straight-4, vertical |
| Fuel type | Diesel |
| Production | – |
| Displacement | 2.3L, 2,289 cc (139.67 cu in) |
| Max. Horsepower | 73.0 PS (54.0 KW; 72.0 HP) at 4,300 rpm |
| Torque output | – |
| Injection pump | Diesel Kiki-Bosch (in-line or VE) |
| Power adder | None |
| Firing order | 1-3-4-2 |
| Cooling system | Liquid-cooling |
| Dimensions (L x H x W): | – |
| Weight | |
Cylinder block
The cylinder block has a monoblock high-strength cast-iron structure with replaceable dry liners and five-bearing-support system. The SD23 engine has a drop-forged steel crankshaft with balance weights, all main and connecting rod bearing surfaces are induction-hardened. Bearings are the precision type, steel-backed tri-metal shell. The central distance of the crankshaft in the SD23 is different from the other SD-family engines (46 mm in SD23 against 50.0 mm in SD22, SD25, and SD33). The connecting rod center distance is 174.2 mm.
The Nissan SD23 motor has an aluminum alloy piston for high strength, lightweight and good heat conductivity; two compression and single oil control ring, they are chrome-plated for long service life. The cylinder bore is 89 mm, piston stroke is 92 mm and the compression ratio rating is 20.5:1.
| Cylinder block | ||
| Cylinder block alloy | Cast iron | |
| Compression ratio: | 20.5:1 | |
| Cylinder bore: | 89 mm (3.50 in) | |
| Piston stroke: | 92 mm (3.62 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Number of main bearings: | 5 | |
| Block Height: | 268.00 mm (10.55 in) | |
| Cylinder liner inner diameter: | 89.000-89.035 mm (3.5039-3.5053 in) | |
| Piston skirt diameter | 88.895-88.935 mm (3.4998-3.5014 in) | |
| Piston ring side clearance (№1): | 0.06-0.100 mm (0.0024-0.0039 in) | |
| Piston ring side clearance (№2): | 0.040-0.080 mm (0.0016-0.0031 in) | |
| Piston ring side clearance (№3): | 0.020-0.060 mm (0.0008-0.0024 in) | |
| Piston ring end gap (№1): | 0.300-0.450 mm (0.0118-0.0177 in) | |
| Piston ring end gap (№2): | 0.200-0.350 mm (0.0079-0.0138 in) | |
| Piston ring end gap (№3): | 0.150-0.300 mm (0.0059-0.0118 in) | |
| Piston pin outer diameter | 25.993-26.000 mm (1.0233-1.0236 in) | |
| Piston pin bore diameter | 26.025-26.038 mm (1.0246-1.0251 in) | |
| Connecting rod center distance: | 174.2 mm (6.86 in) | |
| Crankshaft journal diameter: | 70.907-70.920 mm (2.7916-2.7921 in) | |
| Crankpin diameter: | 52.913-52.926 mm (2.0832-2.0837 in) | |
| Crankshaft center distance: | 46.00 mm (1.8110 in) | |
Cylinder head
The SD23 has a one-piece high-strength cast iron cylinder head, special cast-iron valve inserts are shrink-fitted. It has high-quality cast iron camshaft, lobes are specially processed to improve hardness and durability.
The engine has OHV design with two valves per cylinder: one intake and exhaust made of special heat-resistant steel. The exhaust valve with a stellite-treated surface. Intake valves are 40 mm in diameter, and the exhaust valves are 34 mm. Valves are similar to the SD25 engine.
| Cylinder head | |
| Cylinder head alloy | Cast iron |
| Valve Arrangement: | OHV |
| Valves: | 8 (2 valves per cylinder) |
| Intake valves diameter: | 40.0 mm (1.575 in) |
| Exhaust valves diameter: | 34.0 mm (1.339 in) |
| Valves length: | 117.0 mm (4.61 in) |
| Intake valve stem diameter: | 7.970-7.985 mm (0.3138-0.3144 in) |
| Exhaust valves stem diameter: | 7.945-7.960 mm (0.3128-0.3134 in) |
| Camshaft journal diameter: |
Front:45.434-45.447 mm (1.7887-1.7892 in) Center:43.897-43.910 mm (1.7282-1.7287 in) Front:41.218-41.231 mm (1.6228-1.6233 in) |
| Cam height: | 37.280-37.320 mm (1.4677-1.4693 in) |
Problems and malfunctions
The SD family of Nissan diesel engines are very reliable, strong, and ask for little in the way of maintenance. The engine uses industry-standard BOSCH injection system components (license-built by Diesel Kiki) and is known worldwide as a reliable, long-lived powerplant.
Maintenance data
| Valve clearance (HOT) | |
| Intake valve | 0.35 mm (0.014 in) |
| Exhaust valve | 0.35 mm (0.014 in) |
| Compression pressure | |
| Standard | 30 kg/cm2 (29.4 bar, 427 psi) / 200 rpm |
| Minimun | 25 kg/cm2 (24.5 bar, 356 psi) / 200 rpm |
| Compression differential limit between cylinders | 3.0 kg/cm2 (2.9 bar, 43 psi) / 200 rpm |
| Oil system | |
| Recommended engine oil | Semi Synthetic 10W-30 or 10W-40 (“CD” or higher: “CH”, “CI”) |
| Engine oil capacity | 6.5 liters (6.9 US.qts, 5.7 Imp. qts) |
| Fuel system | |
| Injection timing |
Bosch-Kiki in-line: 20 ° B.T.D.C. / 600 rpm Bosch-Kiki VE: 8 ° B.T.D.C. / 600 rpm |
| Idling |
550-600 rpm (withuot power steering) 650-750 rpm (wiht power steering) |
| Max engine speed under no load |
Bosch-Kiki in-line: 4,200-4,400 rpm Bosch-Kiki VE: 4,500-4,700 rpm |
| Glow plugs | NGK Y-103 |
Tightening torque specs
| Tightening torque specs (engine outer parts) | |
| Water outlet bolt | 10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb |
| Water pump bolt (M8) | 10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb |
| Water pump bolt (M10) | 20-25 Nm; 2.0-2.5 kg·m; 14-18 ft·lb |
| Manifold bolt and nut | 15-18 Nm; 1.5-1.8 kg·m; 11-13 ft·lb |
| Injection pump nut (in-line) | 20-25 Nm; 2.0-2.5 kg·m; 14-18 ft·lb |
| Injection pump nut (VE type) |
Nut: 20-25 Nm; 2.0-2.5 kg·m; 14-18 ft·lb Bolt: 16-22 Nm; 1.6-2.2 kg·m; 12-16 ft·lb |
| Injection nozzle to cylinder head |
Type 1: 59-69 Nm; 6.0-7.0 kg·m; 43-51 ft·lb Type 2: 69-78 Nm; 7.0-8.0 kg·m; 51-58 ft·lb |
| Oil cooler bolt | 10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb |
| Oil cooler pipe nut | 10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb |
| Timing gear cover bolt | 10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb |
| Injection pump timer nut | 59-69 Nm; 6.0-7.0 kg·m; 43-51 ft·lb |
| Injection tube flare nut | 29-34 Nm; 3.0-3.5 kg·m; 22-25 ft·lb |
| Spill tube with cap nut | 39-49 Nm; 4.0-5.0 kg·m; 29-34 ft·lb |
| Oil filter bracket bolt | 26-36 Nm; 2.7-3.7 kg·m; 20-27 ft·lb |
| Alterator bracket bolt | 26-36 Nm; 2.7-3.7 kg·m; 20-27 ft·lb |
| Alterator to adjusting bar bolt | 11-14 Nm; 1.1-1.4 kg·m; 20-27 ft·lb |
| Diesel pump controller bolt | 11-13 Nm; 1.1-1.3 kg·m; 7-9 ft·lb |
| Diesel pump controller bracket bolt | 45-61 Nm; 4.6-6.2 kg·m; 33-45 ft·lb |
| Thermostat housing | 10-131 Nm; 1.0-1.3 kg·m; 7-9 ft·lb |
| Engine internal parts | |
| Main bearing cap bolt | 167-172 Nm; 17.0-17.5 kg·m; 123-127 ft·lb |
| Crank pulley nut | 294-324 Nm; 30-33 kg·m; 217-239 ft·lb |
| Flywheel bolt | 44-49 Nm; 4.5-5.0 kg·m; 33-36 ft·lb |
| Flywheel bolt w/washer | 127-147 Nm; 13-15 kg·m; 94-108 ft·lb |
| Front cover bolt (M6) | 4-6 Nm; 0.4-0.6 kg·m; 2.9-4.3 ft·lb |
| Front cover bolt (M8) | 10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb |
| Front end plate bolt | 10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb |
| Camshaft gear bolt | 44-49 Nm; 4.5-5.0 kg·m; 33-36 ft·lb |
| Oil pump bolt | 13-19 Nm; 1.3-1.9 kg·m; 9-14 ft·lb |
| Oil pan bolt | 7-10 Nm; 0.7-1.0 kg·m; 5.1-7.2 ft·lb |
| Cylinder head bolt |
Sub: 44-54 Nm; 4.5-5.5 kg·m; 33-40 ft·lb Main: 118-127 Nm; 12-13 kg·m; 87-94 ft·lb |
| Rocker arm shaft bolt | 20-25 Nm; 2.0-2.5 kg·m; 14-18 ft·lb |
| Rocker arm lock nut | 20-25 Nm; 2.0-2.5 kg·m; 14-18 ft·lb |
| Camshaft thrust plate bolt | 4-6 Nm; 0.4-0.6 kg·m; 2.9-4.3 ft·lb |
| Connecting rod big end nut | 51-56 Nm; 5.2-5.7 kg·m; 38-41 ft·lb |
| Rocker cover bolt | 10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb |
| Oil jet (for piston) | 29-39 Nm; 3.0-4.0 kg·m; 22-29 ft·lb |
Type 1: Part № of injection nozzle: 16600-90060; 16600-36W00; 16600-T9000
Type 2: Part № of injection nozzle: 16600-37502; 16600-90012; 16600-90019; 16600-J5571; 16600-T3401; 16600-T3470; 16600-T6200; 16600-T6201; 16600-Y8400; 16600-Y8401
Vehicle applications
The SD23 engine has been used in many functions: for forklifts, marine, and stationary applications.
| Model | Years Produced |
| Nissan 720 | – |
| Nissan D21 | – |
| Nissan Urvan/Caravan E23 | – |
| Nissan Cedric Y30 | – |
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