The 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 code | SD25 |
| Layout | Straight-4, vertical |
| Fuel type | Diesel |
| Production | – |
| Displacement | 2.5 L, 2,488 cc (151.82 cu in) |
| Injection pump | Diesel Kiki-Bosch (in-line or VE) |
| Power adder | None |
| Max. Horsepower | 70 HP (71 PS, 52 kW) at 4,000 rpm |
| Torque output | – |
| Firing order | 1-3-4-2 |
| 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 alloy | Cast 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 diameter | 88.895-88.935 mm (3.4998-3.5014 in) | |
| Piston ring side clearance: | №1 | 0.06 – 0.010 mm (0.0024 – 0.0039 in) |
| №2 | 0.04 – 0.08 mm (0.0016 – 0.0031 in) | |
| №3 | 0.02 – 0.06 mm (0.0008 – 0.0024 in) | |
| Piston ring end gap: | №1 | 0.30 – 0.45 mm (0.0118 – 0.0177 in) |
| №2 | 0.20 – 0.35 mm (0.0079 – 0.0138 in) | |
| №3 | 0.15 – 0.30 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 (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 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: | 37.28-37.32 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 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 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 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 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
| Model | Years Produced |
| Nissan 720 | 1983-1986 |
| Nissan D21 Pickup | 1986-1988 |
| Nissan Urvan | – |
| Nissan Cabstar H40 | – |
| Nissan Atlas F22 | – |
| Nissan Civilian W40 | – |
Author:
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
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 ??
Very good service …