Nissan MR20DE / Renault M4R

Nissan MR20DEThe Nissan MR20DE is a 2.0 l (1,997 cc, 121,68 cu.in.) straight-four 4-stroke natural aspirated gasoline engine from Nissan MR-family. This engine was the first engine from new Nissan MR-series. The MR20DE engine was co-developed with Renault and in the Renault production line it is called M4R. This engine is a substitution of early Nissan QR20DE.

The MR20DE (M4R) features a lightweight aluminum block with a fully balanced five-bearings crankshaft and aluminum head with two camshafts (DOHC) and four valves per cylinder. Compression ratio rating is 10.2:1. Cylinder bore and piston stroke are 84.0 mm (3.3 in) and 90.1 mm (3.54 in), respectively.

The MR20DE (M4R) engine has an electronic throttle, continuous variable valve timing system CVTC on intake camshaft, EGR system and electronic ignition with individual coils on each spark plug.

It produces from 133 to 147 PS (98 to 108 kW; 131 to 145 HP) of horsepower and 191-210 Nm (141-155 lb·ft) of torque.

The breakdown of the engine code is as follows:

  • MR – Engine Family
  • 20 – 2.0 Liter Displacement
  • D – DOHC (Dual Overhead Camshafts)
  • E – Multi Point Fuel Injection

General information

Engine Specifications
Engine codeMR20DE / M4R
LayoutFour stroke, Inline-4 (Straight-4)
Fuel typeGasoline (petrol)
Production2005-
Displacement2.0 L, 1,997 cc (121.68 cu in)
Fuel systemMulti Point Fuel Injection
Power adderNone
Power output 133 PS (98 kW, 131 HP) at 5,200 rpm
137 PS (101 kW, 135 HP) at 5,200 rpm
140 PS (103 kW, 138 HP) at 5,100 rpm
147 PS (108 kW, 145 HP) at 5,600 rpm
Torque output 191 Nm (19.47 kg·m, 141 lb·ft) at 4,400 rpm
193 Nm (19.68 kg·m, 142 lb·ft) at 4,800 rpm
196 Nm (19.98 kg·m, 144 lb·ft) at 4,400 rpm
210 Nm (21.41 kg·m, 155 lb·ft) at 4,400 rpm
Firing order1-3-4-2
Dimensions (L x W x H):
Weight

Cylinder block

The MR-family engines use the same technology as in the HR-series. Cylinders in the Nissan MR20DE / Renault M4R engines are fitted at an offset to minimize friction arising from the angle of the connecting rod as a piston descends into the cylinder. The resulting smoother reciprocating motion of the pistons contributes to high power output and high torque as well as fuel economy. Also, the structure is designed so that the piston remains in the upper part of the cylinder longer than in a conventional engine (piston velocity slows down). This permits more efficient use of combustion energy and effectively improves thermal efficiency.

The MR-family engines have a cracking-processed connecting rod. These integrally cast con rods offer lighter weight than conventional con rods, which are constructed in two parts, separated at the eye where they join the crankshaft. The cracking processed conrod is manufactured in one piece, then the lower connecting rod eye is broken in two (the cracking process) and, finally, the two parts are rejoined after mounting. Mating of the uneven surfaces created by the cracking process results in a very precise joint.

The crankshaft and camshaft journals are finished with a polishing tape to produce a mirror-like finish. The result is a thorough reduction in friction on these bearing surfaces of key engine components.

The coolant distribution system has been thoroughly redesigned in all areas, incorporating it into the block and head.

Cylinder block
Cylinder block alloyAluminium
Compression ratio:10.2:1
Cylinder bore:84.0 mm (3.307 in)
Piston stroke:90.1 mm (3.547 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:5
Cylinder inner diameter (standard):84.000 – 84.010 mm (3.3071 – 3.3075 in)
Piston skirt diameter (standard):83.970 – 83.980 mm (3.3059 – 3.3063 in)
Piston pin outer diameter:19.989 – 19.995 mm (0.7870 – 0.7872 in)
Piston ring side clearance:Top0.040 – 0.080 mm (0.0016 – 0.0031 in)
Second0.030 – 0.070 mm (0.0012 – 0.0028 in)
Oil0.015 – 0.185 mm (0.001 – 0.007 in)
Piston ring end gap:Top0.20- 0.30 mm (0.008 – 0.012 in)
Second0.50 – 0.65 mm (0.020 – 0.026 in)
Oil0.15 – 0.45 mm (0.006 – 0.018 in)
Connecting rod bushing inner diameter:20.000 – 20.012 mm (0.7874 – 0.7879 in)
Connecting rod big end diameter:47.000 – 47.001 mm (1.8504 – 1.8504 in)
Connecting rod center distance:138.97 – 139.07 mm (5.471 – 5.475 in)
Crankshaft main journal diameter:51.978 – 51.979 mm (2.0464 – 2.0464 in)
Crankpin diameter:43.970 mm (1.7311 in)
Crankshaft center distance:44.87 – 44.89 mm (1.7673 – 1.7705 in)

Main bearing cap bolts tightening procedure and torque specs:

  • Step 1: 34.3 Nm; 3.5 kg·m; 25 ft·lb
  • Step 2: Turn all bolts 60°

After securing bearing cap bolts, make sure crankshaft turns smoothly by hand.

Connecting rod bearing bolts

  • Step 1: 27.4 Nm; 2.8 kg·m; 20 ft·lb
  • Step 2: 0 Nm; 0 kg·m; 0 ft·lb
  • Step 3: 19.6 Nm; 2.0 kg·m; 14 ft·lb

Crankshaft pulley bolt

  • Step 1: 68.6 Nm; 7.0 kg·m; 51 ft·lb
  • Step 2: 0 Nm; 0 kg·m; 0 ft·lb
  • Step 3: 29.4 Nm; 3.0 kg·m; 22 ft·lb

Flywheel (M/T) or Drive plate (CVT) fixing bolts

  • 108 Nm; 11 kg·m; 80 ft·lb

Cylinder head

The cylinder head is made of strong, light aluminum alloy which gives it good cooling efficiency. Each camshaft is supported by five bearings. The MR20DE (M4R) has continuous variable valve timing system (C-VTC) on the intake camshaft. C-VTC enables variable valve timing in response to engine rpm and throttle opening. Enhanced control and reduced system friction improve response and optimize torque characteristics.

The camshaft is driven by the special “silent chain”. This “silent chain” reduces impact noise to deliver quieter operation. Impact noise is generated by the camshaft drive chain as its pins mesh with the sprockets. For the MR engine, Nissan redesigned the links so they engage the sprockets at points in addition to the pins themselves, thereby distributing impact to reduce this noise.

Intake valves are 34 mm in diameter, intake duration is 232°, and the exhaust valves are 27.7 mm, exhaust duration is 220°. The MR20DE motor does not have hydraulic lifters, so special valve lifters are used to adjust the valve clearance.

The engine has a plastic intake manifold with an integrated tumble control valve. The MR20DE is equipped with EGR (Exhaust Gas Recirculation) system. This system returns a portion of the exhaust gas to the intake side to reduce fuel consumption and minimize emission.

The MR20DE-M4R engine has a front air intake and rear exhaust system layout. The system has long intake runners effective in promoting ample torque at low and mid-range engine speeds, and also achieves smooth exhaust flow. The straight exhaust system reduces flow-resistance.

Cylinder head
Valve Arrangement:DOHC, chain drive
Cylinder head height:130.9 mm (5.15 in)
Valves:16 (4 valves per cylinder)
Valve timing:INTAKE232°
EXHAUST220°
Valve head diameter:INTAKE33.8 – 34.1 mm (1.331 – 1.343 in)
EXHAUST27.6 – 27.9 mm (1.087 – 1.098 in)
Valve length:INTAKE106.27 mm (4.184 in)
EXHAUST105.26 mm (4.144 in)
Valve stem diameter:INTAKE5.465 – 5.480 mm (0.2152 – 0.2157 in)
EXHAUST5.455 – 5.470 mm (0.2148 – 0.2154 in)
Valve spring free length:INTAKE45.59 – 46.96 mm (1.7949 – 1.8488 in)
EXHAUST45.13 – 46.40 mm (1.7768 – 1.8268 in)
Camshaft cam height:INTAKE45.265 – 45.455 mm (1.7821 – 1.7896 in)
EXHAUST43.775 – 43.965 mm (1.7234 – 1.7309 in)
Camshaft journal diameter:№127.935 – 27.955 mm (1.0998 – 1.1006 in)
№2, 3, 4, 524.950 – 24.970 mm (0.9823 – 0.9381 in)

Head tightening procedure and torque specs:

  • Step 1: 40 Nm; 4.1 kg·m; 30 ft·lb
  • Step 2: Turn all bolts 100°
  • Step 3: Loosen all bolts completely
  • Step 4: 40 Nm; 4.1 kg·m; 30 ft·lb
  • Step 5: Turn all bolts 100°
  • Step 6: Turn all bolts another 100°

Camshaft sprocket bolts

  • Intake: 35.0 Nm; 3.6 kg·m; 26 ft·lb
  • Exhaust: 88.2 Nm; 9.0 kg·m; 65 ft·lb

Problems and malfunctions

The Nissan MR20 is reliable and durable. This engine sometimes has a problem with alternator belt (whistle noise). It needs to tighten or replace the old belt by a new one.

One of the most unpleasant is crack in the cylinder head. It happens if the spark plugs are screwed very tight, the cracks at the screw appear. This problem may be solved only by changing a cylinder head for the new. To avoid the problem, it is necessary to screw the spark plugs with tightening torque no more than 18-19 Nm and only on the cold engine.

The engine has a timing chain, their service life is about 150,000 miles of mileage (200,000-250,000 km). The valve clearance needs to be adjusted every 60,000 miles of mileage (90,000 km). The MR20DE motor life expectancy is 200,000 miles of mileage (300,000 km) or more.

Maintenance data

Valve clearance (HOT)
Intake valve0.304 – 0.416 mm (0.012 – 0.016 in)
Exhaust valve0.308 – 0.432 mm (0.012 – 0.017 in)
Compression pressure
Standard14.2 kg/cm2 (202 psi) / 250 rpm
Minimun11.6 kg/cm2 (165 psi) / 250 rpm
Compression differential limit between cylinders1.0 kg/cm2 (15 psi) / 250 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 API
Engine oil capacity (Refill capacity) With filter change 3.8 l (4.0 qt.)
Without filter change 3.6 l (3.9 qt.)
Oil change interval, km (miles)5,000-10,000 (3,000-6,000)
Oil Pressure, kPa (bar, kg/cm 2, psi) Idle speed: More than 60 (0.6, 0.61, 9)
2,000 rpm: More than 200 (2.0, 2.0, 29)
Ignition system
Spark plugNGK: PLZKAR6A-11 (Platinum-tipped)
Spark plug gap1.1 mm (0.043 in)
Spark plug tightening torque19.6 Nm, 2.0 kg·m, 14 ft·lb

Valve clearance adjustment data

Calculate the thickness of new adjusting valve lifter so valve clearance comes within specified values.

R = Thickness of removed valve lifter
N = Thickness of new valve lifter
M = Measured valve clearance

Intake:
N = R + [M – 0.30 mm (0.012 in)]
Exhaust:
N = R + [M – 0.33 mm (0.013 in)]

Valve lifters are available in 26 sizes range from 3.00 mm (0.1181 in) to 3.50 mm (0.1378 in), in steps of 0.02 mm (0.0008 in).

Example (intake valve):
R = 3.10 mm
M = 0.52 mm
N = 3.10 + (0.52 – 0.30) = 3.32 mm, so we need a valve lifter with identification mark 332.

ColdHot
Intake0.26 – 0.34 mm (0.010 – 0.013 in)0.304 – 0.416 mm (0.012 – 0.016 in)
Exhaust0.29 – 0.37 mm (0.011 – 0.015 in)0.308 – 0.432 mm (0.012 – 0.017 in)

Vehicle applications

ModelYears Produced
Nissan Serena2005–
Renault Samsung SM52005–
Nissan Bluebird Sylphy2005–2012
Renault Clio2006–
Nissan X-Trail2007–
Nissan Qashqai2007–
Nissan Sentra2007–2012
Renault Laguna2007–
Nissan Teana (J32)2008–2014
Renault Safrane2008–
Renault Mégane III2008–
Renault Scénic2009–
Renault Fluence2009–
Renault Samsung SM32009–
Renault Latitude2009–
Nissan NV2002013–
Nissan Sentra (Brazil)2013–
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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.

9 Comments

  1. The spark plug instructions for the MR20DE say 23 Nm.
    Would it be better to answer the 23 Nm or follow your recommendation of 19 Nm?

    • From manual for Nissan Sentra 2008 with mr20de: spark plug torque 19.6 Nm, 2.0 kg·m, 14 ft·lb, so 23 Nm is too much you can damage the cylinder head.

  2. nissan mr20 los resortes de valvulas de admicion y escape son diferentes qequiero saber la posicion de los resorte en su respetivo lugar

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