NIssan P40

NIssan P40The Nissan P40 is a 4.0 liter (3,956 cc, 241.40 cu-in) straight-six, four-stroke cycle, liquid-cooled gasoline engine manufactured by Nissan Diesel Motor Co., Ltd. from 1959.

The Nissan P40 engine has a cast-iron block, overhead valves, featuring bathtub-shaped combustion chambers, a fully balanced seven-bearing crankshaft, and a two-barrel carburetor.

The P40 engine in the Nissan Patrol 160 (MQ\MK) was different from the P40 that was used in the Nissan Patrol G60. The bore and stroke are the same so therefore the pistons and rods are the same. The cylinder heads are also the same, but the intake manifold is different.

Cylinder bore and piston stroke are 85.7 mm (3.37 in) and 114.3 mm (4.50 in), respectively. The compression ratio is 7.6:1. It produced form 116.0 PS (85.0 KW; 114.0 HP) at 3,400 rpm up to 145.5 PS (107.0 KW; 143.5 HP) at 3,400 rpm of horsepower and from 270.0 Nm (27.5 kg·m; 199.3 lbf·ft) at 2,000 rpm to 318.0 Nm (32.4 kg·m; 234.7 lbf·ft) at 2,000 rpm of torque.

The breakdown of the engine code is as follows:

  • P – Engine Family
  • 40 – 4.0 Liter Displacement

General information

Engine Specifications
Engine codeP / P40
LayoutFour stroke, Inline-6 (Straight-6)
Fuel typeGasoline
Displacement4.0 L, 3,956 cc (241.40 cu-in)
Max. horsepower145.5 PS (107.0 KW; 143.5 HP) at 3,400 rpm
Torque output318.0 Nm (32.4 kg·m; 234.7 lbf·ft) at 2,000 rpm
Cooling systemLiquid-cooling
Fuel systemCarburetor
Power adderNone
Firing order1-5-3-6-2-4
Dimensions (L x H x W):904 x 671 x 937 mm
Weight650 lbs (295 kg)

Cylinder block

The P40 engine has a cast-iron cylinder block, bore is 85.7 mm (3.374 in) and stroke is 114.3 mm (4.500 in). The pistons are each fitted with two compression rings and a single oil ring. The crankshaft of the P40 engine is fully balanced and supported by seven main bearings.

Cylinder block
Cylinder block alloyCast iron
Compression ratio:7.6:1
Cylinder bore:85.7 mm (3.374 in)
Piston stroke:114.3 mm (4.500 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:7
Cylinder inner diameter (standard):85.690-85.740 mm (3.3736-3.3756 in)
Piston skirt diameter (standard):85.650-85.699 mm (3.3720-3.3740 in)
Piston pin outer diameter:20.648-20.653 mm (0.8129-0.8131 in)
Piston ring side clearance:Top0.031-0.078 mm (0.0012-0.0031 in)
Second0.031-0.078 mm (0.0012-0.0031 in)
Piston ring end gap:Top0.25-0.40 mm (0.0098-0.0157 in)
Second0.15-0.30 mm (0.0059-0.0118 in)
Oil0.20-0.90 mm (0.008-0.035 in)
Connecting rod center distance:200 mm (7.87 in)
Connectin rod small end inner diameter:20.618-20.630 mm (0.8117-0.8122 in)
Crankshaft journal diameter:69.275-69.300 mm (2.7274-2.7283 in)
Crankpin diameter:57.131-57.150 mm (2.2492-2.2500 in)
Crankshaft center distance:57.150 mm (2.25 in)

Cylinder head

Intake valves are 43.0 mm in diameter, intake duration is 244°, and the exhaust valves are 36.2 mm, exhaust duration is 244°.

Cylinder head
Valve Arrangement:OHV, chain drive
Valves:12 (2 valves per cylinder)
Intake/Exhaust duration:244° / 244°
Valve head diameter:INTAKE43.0 mm (1.693 in)
EXHAUST36.2 mm (1.425 in)
Valve length:INTAKE130.05-130.35 mm (5.1201-5.1319 in)
EXHAUST131.35-131.65 mm (5.1712-5.1831 in)
Valve stem diameter:INTAKE8.637-8.650 mm (0.3400-0.3406 in)
EXHAUST8.627-8.640 mm (0.3396-0.3402 in)
Cam height:INTAKE41.246 mm (1.6239 in)
EXHAUST41.246 mm (1.6239 in)
Outer camshaft journal diameter:№149.124-49.149 mm (1.9340-1.9350 in)
№248.920-48.925 mm (1.9260-1.9270 in)
№348.161-48.641 mm (1.9140-1.9150 in)
№448.311-48.336 mm (1.9020-1.9030 in)
Rocker shaft outer daimetr19.975-20.000 mm (0.7864-0.7874 in)
Rocker arm bushing bore daimetr20.020-20.033 mm (0.7882-0.7887 in)

Maintenance data

Valve clearance (HOT)
Intake valve0.38 mm (0.015 in)
Exhaust valve0.38 mm (0.015 in)
Compression pressure
Standard11.5 kg/cm2 (11.28 bar, 164 psi) / 250 rpm
Minimun10.5 kg/cm2 (10.30 bar, 149 psi) / 250 rpm
Compression differential limit between cylinders1 kg/cm2 (0.98 bar, 14 psi) / 350 rpm
Oil system
Oil consumption , L/1000 km (qt. per miles)up to 0.5 (1 qt. per 1200 miles)
Recommended engine oil 5W-30
Oil type APISE
Engine oil capacity (Refill capacity) With filter change 5.7 liters (6.0 US.qts, 5.0 Imp. qts)
Without filter change 5.1 liters (5.4 US.qts, 4.5 Imp. qts)
Oil change interval, km (miles)5,000-10,000 (3,000-6,000)
Ignition system
Ignition timing (B.T.D.C./rpm) 10°/550 rpm – Except Europe and Hong Kong
5°/650 rpm – For Europe and Hong Kong
10°/500 rpm – For Australia
Spark plug Cold: BP7ES, L44PW, BPR7ES (NGK)
Standard: BP6ES, L45PW, BPR6ES (NGK)
Spark plug gap0.8-0.9 mm (0.03 -0.035 in)
Point gap0.45-0.55 mm (0.018-0.022 in)
Dwell angle35°-40°

Tightening torque specs

Tightening torque specs
Main bearing cap bolt98-118 Nm; 10-12 kg·m; 72-87 ft·lb
Connecting rod big end nut44-59 Nm; 4.5-6.0 kg·m; 33-43 ft·lb
Water pump bolt (M10)20-25 Nm; 2.0-2.5 kg·m; 14-18 ft·lb
Flywheel bolt78-98 Nm; 8.0-10.0 kg·m; 58-72 ft·lb
Front cover bolt M8: 11-21 Nm; 1.1-2.1 kg·m; 8-15 ft·lb
M10: 30-40 Nm; 3.1-4.1 kg·m; 22-30 ft·lb
Front plate bolt30-40 Nm; 3.1-4.1 kg·m; 22-30 ft·lb
Fliwheel housing bolt51-72 Nm; 5.3-7.4 kg·m; 39-54 ft·lb
Cylinder head bolt68-88 Nm; 7.0-9.0 kg·m; 51-65 ft·lb
Rocker shaft bracket bolt34-48 Nm; 3.5-4.9 kg·m; 25-35 ft·lb
Valve rocker adjusting screw30-38 Nm; 3.0-3.8 kg·m; 22-28 ft·lb
Camshaft sprocket bolt30-40 Nm; 3.1-4.1 kg·m; 22-30 ft·lb
Camshaft locating plate bolt6-8 Nm; 0.6-0.8 kg·m; 4.3-5.8 ft·lb
Oil pump bolt25-34 Nm; 2.5-3.5 kg·m; 18-25 ft·lb
Water pump nut and bolt25-34 Nm; 2.5-3.5 kg·m; 18-25 ft·lb
Crank pulley nut149-163 Nm; 15.2-16.3 kg·m; 110-120 ft·lb
Rocker cover bolt18-27 Nm; 1.8-2.8 kg·m; 13-20 ft·lb
Spark plug18-24 Nm; 1.8-2.4 kg·m; 13-17 ft·lb
Manifold bolt and nut25-34 Nm; 2.5-3.5 kg·m; 18-25 ft·lb
Water outlet bolt10-12 Nm; 1.0-1.2 kg·m; 7-9 ft·lb
Thermostat housing10-12 Nm; 1.0-1.2 kg·m; 7-9 ft·lb
Distributor support bolt10-12 Nm; 1.0-1.2 kg·m; 7-9 ft·lb
Alternator bracket22-29 Nm; 2.2-3.0 kg·m; 16-22 ft·lb
Engine mouting bracket37-50 Nm; 3.7-5.0 kg·m; 27-37 ft·lb
Carburetor nut14-18 Nm; 1.4-1.8 kg·m; 10-13 ft·lb
Fuel pump nut11-21 Nm; 1.1-2.1 kg·m; 8-15 ft·lb

Vehicle applications

ModelYears Produced
Nissan Patrol 4W661959-1960
Nissan Carrier 4W731959-
Nissan 680 Truck1959-1968
Nissan 690 Bus1960-1968
Nissan Patrol 601960-1980
Nissan FR401963-1968
Nissan 681 Truck1968-1969
Nissan 691 Bus1968-1969
Nissan G7801969-
Nissan Patrol 1601980-1989
Nissan Patrol 2601986-2003
Nissan Cabstar E690
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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We try to use verified sources and official documentation, however, differences between sources or errors in entering information may occur. We do not provide advice on technical issues related to the engines operation or repair. We do not recommend using provided information for engines repairing engines or spare parts ordering, use only official service manuals and spare-parts catalogs.


  1. That is a picture of the Nissan “P” engine inside of a Nissan Patrol. The P40 has a different intake/exhaust setup

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