Nissan SD23

Nissan SD23 diesel engineThe 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 codeSD23
LayoutStraight-4, vertical
Fuel typeDiesel
Displacement2.3L, 2,289 cc (139.67 cu in)
Max. Horsepower73.0 PS (54.0 KW; 72.0 HP) at 4,300 rpm
Torque output
Injection pumpDiesel Kiki-Bosch (in-line or VE)
Power adderNone
Firing order1-3-4-2
Cooling systemLiquid-cooling
Dimensions (L x H x W):

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 alloyCast 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 diameter88.895-88.935 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 diameter25.993-26.000 mm (1.0233-1.0236 in)
Piston pin bore diameter26.025-26.038 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 alloyCast 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 valve0.35 mm (0.014 in)
Exhaust valve0.35 mm (0.014 in)
Compression pressure
Standard30 kg/cm2 (29.4 bar, 427 psi) / 200 rpm
Minimun25 kg/cm2 (24.5 bar, 356 psi) / 200 rpm
Compression differential limit between cylinders3.0 kg/cm2 (2.9 bar, 43 psi) / 200 rpm
Oil system
Recommended engine oilSemi Synthetic 10W-30 or 10W-40 (“CD” or higher: “CH”, “CI”)
Engine oil capacity6.5 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 plugsNGK Y-103

Tightening torque specs

Tightening torque specs (engine outer parts)
Water outlet bolt10-13 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 nut15-18 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 bolt10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb
Oil cooler pipe nut10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb
Timing gear cover bolt10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb
Injection pump timer nut59-69 Nm; 6.0-7.0 kg·m; 43-51 ft·lb
Injection tube flare nut29-34 Nm; 3.0-3.5 kg·m; 22-25 ft·lb
Spill tube with cap nut39-49 Nm; 4.0-5.0 kg·m; 29-34 ft·lb
Oil filter bracket bolt26-36 Nm; 2.7-3.7 kg·m; 20-27 ft·lb
Alterator bracket bolt26-36 Nm; 2.7-3.7 kg·m; 20-27 ft·lb
Alterator to adjusting bar bolt11-14 Nm; 1.1-1.4 kg·m; 20-27 ft·lb
Diesel pump controller bolt11-13 Nm; 1.1-1.3 kg·m; 7-9 ft·lb
Diesel pump controller bracket bolt45-61 Nm; 4.6-6.2 kg·m; 33-45 ft·lb
Thermostat housing10-131 Nm; 1.0-1.3 kg·m; 7-9 ft·lb
Engine internal parts
Main bearing cap bolt167-172 Nm; 17.0-17.5 kg·m; 123-127 ft·lb
Crank pulley nut294-324 Nm; 30-33 kg·m; 217-239 ft·lb
Flywheel bolt44-49 Nm; 4.5-5.0 kg·m; 33-36 ft·lb
Flywheel bolt w/washer127-147 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 bolt10-13 Nm; 1.0-1.3 kg·m; 7-9 ft·lb
Camshaft gear bolt44-49 Nm; 4.5-5.0 kg·m; 33-36 ft·lb
Oil pump bolt13-19 Nm; 1.3-1.9 kg·m; 9-14 ft·lb
Oil pan bolt7-10 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 bolt20-25 Nm; 2.0-2.5 kg·m; 14-18 ft·lb
Rocker arm lock nut20-25 Nm; 2.0-2.5 kg·m; 14-18 ft·lb
Camshaft thrust plate bolt4-6 Nm; 0.4-0.6 kg·m; 2.9-4.3 ft·lb
Connecting rod big end nut51-56 Nm; 5.2-5.7 kg·m; 38-41 ft·lb
Rocker cover bolt10-13 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.

ModelYears Produced
Nissan 720
Nissan D21
Nissan Urvan/Caravan E23
Nissan Cedric Y30
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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