Nissan SD25

Nissan SD25 diesel engineThe Nissan SD25 is a 2.5 l (2,488 cc) straight four, water-cooled diesel engine from Nissan SD family.

The compression ratio is 20.7:1 and 21.4:1 only for Datsun/Nissan 720 (Non-California) or 21.9:1 (for California) Cylinder bore and the piston stroke is 89.0 mm (3.50 in) and 100 mm (3.94 in), respectively.

The Nissan SD25 engine produced 70 HP (71 PS, 52 kW) of horsepower at 4,000 rpm.

The SD25 engine was equipped with Kiki-Bosch in-line fuel or VE fuel injection pump, depending on market and vehicle mode.

The breakdown of the engine code is as follows:

  • SD – Engine Family
  • 25 – 2.5 Liter Displacement

General information

Engine Specifications
Engine codeSD25
LayoutStraight-4, vertical
Fuel typeDiesel
Production
Displacement2.5 L, 2,488 cc (151.82 cu in)
Injection pumpDiesel Kiki-Bosch (in-line or VE)
Power adderNone
Max. Horsepower70 HP (71 PS, 52 kW) at 4,000 rpm
Torque output
Firing order1-3-4-2
Dimensions (L x H x W):
Weight

Cylinder block

The cylinder block has a monoblock high-strength cast-iron structure with replaceable dry liners. The SD25 engine has five main bearings, 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 Nissan SD25 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 100 mm.

Cylinder block
Cylinder block alloyCast iron
Compression ratio:20.7:1
21.4 (only for Datsun/Nissan 720 Pickup, Non-California)
21.9 (only for Datsun/Nissan 720 Pickup, California)
Cylinder bore:89 mm (3.50 in)
Piston stroke:100 mm (3.94 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:№10.06 – 0.010 mm (0.0024 – 0.0039 in)
№20.04 – 0.08 mm (0.0016 – 0.0031 in)
№30.02 – 0.06 mm (0.0008 – 0.0024 in)
Piston ring end gap:№10.30 – 0.45 mm (0.0118 – 0.0177 in)
№20.20 – 0.35 mm (0.0079 – 0.0138 in)
№30.15 – 0.30 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 (5.5295 – 5.5335 in)
Connecting rod center distance:170.0 mm (6.69 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:50.00 mm (1.9685 in)

Cylinder head

The SD25 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.

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:37.28-37.32 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 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 l (6.9 U.S. qt)
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 Bosch-Kiki in-line and VE:
550-600 rpm (withuot power steering)
650-750 rpm (wiht power steering)
Max engine speed under no load Bosch-Kiki in-line: 4200-4400 rpm
Bosch-Kiki VE: 4500-4700 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

ModelYears Produced
Nissan 7201983-1986
Nissan D21 Pickup1986-1988
Nissan Urvan
Nissan Cabstar H40
Nissan Atlas F22
Nissan Civilian W40
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5 Comments

  1. Hola buen tarde tengo un motor nissan sd25 2.5 y no puedo conceguir el repuesto de carcasa de enfriado de aceite ustedes me pueden ayudar con eso desde ya muchas gracias

  2. Hi curious if a transmission will fit from a gas engine datsun into my diesel Nissan both standard 2wd because my 85 Nissan 720 pops out of 1st under compression and really goes deep into 2nd then pushes outward when I accelerate is there a way to adjust something or change a bushing on the shifter maybe? My choke or kickdown cable isn’t hooked up neither is the parking brake can the kickdown be affecting this anyway? Great lil truck I just want it to be reliable and not let go of a bearing or something in the tranny

    • you’ll need your existiong belhousing and donor transmission from a 2wd gas ka/ z series 5 speed manual ( d21), you might have to swap some stuff over like spedo gear in the tailshaft housing but its doable,

      • hello Jack, i have a 1983 SD 25 NISSAN DIESEL ENGINE WHICH ONLY HAS 112000 EASY DUTY MILES ON IT SENCE NEW , WHICH HAS ALWAYS BEEN WELL MAINTAINED AND SERVICED, I REMOVED IT FROM MY BELOVED 1983 Nissan Urvan which got rolled over in a severe wind storm , twisted and, de glassed, but all mechanics in perfect order and runs like it was new ! my question is at 72 HP. would that engine be a very good addition to repower my 1963 404 Mercedes Unimog six-cylinder original, thirsty petrol engine, it sure,has plenty of Tork , what do you think ??

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