The Kubota Z851 is a 0.9 L (867 cc, 52.9 cu·in) straight-two, water-cooled, naturally aspirated, indirect injection, vertical diesel engine, manufactured by Kubota for the L1801 utility tractor.
A 82.0 mm (3.23 in) cylinder bore and 82.0 mm (3.23 in) piston stroke give the Kubota Z851 engine a total of 867 cc (52.9 cu·in) of displacement.
The Z851 diesel engine produced 18.2 PS (13.4 kW; 18.0 HP) at 3,000 rpm of output power.
The breakdown of the engine code is as follows:
- Z – 2-cylinders
- 851 – Approximate displacement 850 cc
General information
| Engine Specifications | |
| Engine code | Z851 |
| Layout | Straight-2, vertical diesel engine |
| Fuel type | Diesel fuel No.2-D |
| Production | – |
| Displacement | 0.9 L, 867 cm3 (52.9 cu in) |
| Max. Horsepower | 18.2 PS (13.4 kW; 18.0 HP) at 3,000 rpm |
| Torque output | – |
| Injection type | Indirect injection |
| Cooling system | Liquid-cooled |
| Fuel system | Fuel injection pump |
| Fuel nozzle | – |
| Starting system | Electric starting with 12V starter |
| Starting support device | – |
| Governor | Centrifugal ball mechanical governor |
| Power adder | None |
| Firing order | 1-2 |
| Dimensions (L x W x H): | – |
| Weight | – |
Cylinder block
| Cylinder block | ||
| Compression ratio: | – | |
| Cylinder bore: | 82.0 mm (3.23 in) | |
| Piston stroke: | 82.0 mm (3.23 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Cylinder inner diameter: | 82.000-82.022 mm (3.2283-3.2292 in) | |
| Piston skirt diameter | – | |
| Piston ring side clearance: | Second | 0.090-0.120 mm (0.004-0.005 in) |
| Oil | 0.020-0.050 mm (0.0008-0.0020 in) | |
| Piston ring end gap: | Top | 0.300-0.450 mm (0.0118-0.0177 in) |
| Second | 0.300-0.450 mm (0.0118-0.0177 in) | |
| Oil | 0.250-0.450 mm (0.0099-0.0177 in) | |
| Piston pin outer diameter | 23.002-23.011 mm (0.9056-0.9059 in) | |
| Crankshaft main journal diameter: | 51.921-51.940 mm (2.0441-2.0449 in) | |
| Crankpin diameter: | 43.959-43.975 mm (1.7307-1.7313 in) | |
Cylinder head
| Cylinder head | ||
| Valve Arrangement: | OHV, gear drive | |
| Valves: | 4 (2 valves per cylinder) | |
| Valve timing: | INTAKE | – |
| EXHAUST | – | |
| Valve seat width: | INTAKE | 2.100 mm (0.080 inch) |
| EXHAUST | 2.100 mm (0.080 inch) | |
| Valve stem diameter: | INTAKE | 7.960-7.975 mm (0.3134-0.3140 in) |
| EXHAUST | 7.960-7.975 mm (0.3134-0.3140 in) | |
| Valve spring free length: | INTAKE | 42.0 mm (1.6535 in) |
| EXHAUST | 42.0 mm (1.6535 in) | |
| Camshaft journal diameter: | 39.935-39.950 mm (1.5722-1.5728 in) | |
Maintenance data
| Valve clearance | |
| Intake valve | 0.18-0.22 mm (0.007-0.009 in) |
| Exhaust valve | 0.18-0.22 mm (0.007-0.009 in) |
| Oil system | |
| Recommended engine oil | DS or DM |
| SAE viscosity number | SAE 80 |
| Engine oil capacity | 3.8 liters (4.02 US.qts, 3.34 Imp. qts) |
| Fuel system | |
| Injection timing: | 25° B.T.D.C. |
| Fuel injection pressure | 13.73-14.71 MPa (140-150 kgf/cm2, 1991-2133 psi) |
| Cooling system | |
| Coolant capacity: | 5.3 liters (5.6 US.qts, 4.7 Imp. qts) |
| Electrical system | |
| Battery: | 12V, 65Ah or equivalent |
Where is the thermostat located on a Kubota z851 motor