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Typical problems and sores of the QR25DE engine

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The QR25DE motor which basis the aluminum block, is fellow of the QR20DE motor. They are distinguished only bent shaft which on 2.5 liter motor has piston stroke in 100 mm., the shortened connecting rods, and also other cam shaft. Diameters of cylinders at the same time remained they are 89 mm. Thanks to all changes the 2.5 liters motor began to have, in difference from 2.0-liter, more pull-rod, the good pickup from bottoms has appeared. Is also and bad points at this cursor – because of big discharge angle of short connecting rod of QR25DE experiences rather big strain on cylinders, on the bucket and ring with connecting rods. As a result, появилоь bigger friction force, has increased temperature and properties of lubricant have decreased.

Several years later after emergence of this engine it became clear to engineers that its resource concedes a little to the two-liter fellow therefore in 2007 there was advanced version in which cam shafts, buckets and inlet receiver have been changed, have strengthened connecting rods, have transferred balancing system. It has positively affected engine resource, now at due use and service this model can quite “run” both 300, and 400, and 500 thousand km without kapitalka. There are no hydrocompensator bars on the engine therefore resetting of valves of times in 80-100 thousand km is prescribed it. run.

For the Nissan Primera car there was also version of the motor with direct injection of fuel and with compression ratio 10.7. This QR25DD model was called.

The QR25 engine in various versions was installed on 16 various models of cars: It is Nissan Altima, Bassara, Frontier, Maxima, Murano, Pathfinder, Primera, Presage, Sentra, Serena, Rogue, Teana, X-Trail, Infiniti QX60 Hybrid, Suzuki Equator and Renault Koleos.

Typical problems and sores of the QR25DE engine.

The main and, in fact, only global problem of this motor is Gers oils (from 1.0 to 2.0 liters on 1 thousand km.) which is dictated by the lain piston rings. As a rule, this process begins to 120-150 thousand km. Also there were numerous cases when because of design of rings – they begin to be recut and, as a result, the mirror of cylinders “is strongly killed” that leads to the subsequent boring of the block.

  1. Stretching of the timing chain.
  2. Oil leak and high oil consumption.
  3. Vibrations.
  4. Overheating.

Approximately to 120-130 thousand km. gas distribution mechanism chain stretches. And for the rest – quite reliable and predictable motor. Fill in regularly good oil, you watch candles and everything will be good.

CYLINDER BLOCK

The QR25DE has an aluminium block, cylinder bore is 89.0 mm (3.504 in) and piston stroke is 100.0 mm (3.94 in), compression ratio are ranging from 9.5:1 to 10.5:1 depending on the vehicle.

The pistons are each fitted with two compression rings and single oil ring, cast steel connecting rods are 143.0 mm (5.63 in.) long. The crankshaft for QR25DE engine has two balancer shafts and supported by five main bearings. The crankshaft main journal diameter is 54.97 mm (2.164 in) and crankpin diameter is 44.97 mm (1.77 in.)

Cylinder block
Cylinder block alloyCast iron
Compression ratio:9.5:1 to 10.5:1
Cylinder bore:89.0 mm (3.50 in)
Piston stroke:100.0 mm (3.94 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:5
Block Height:
Cylinder inner diameter (standard):89.010-89.020 mm (3.5043-3.5047 in)
Piston skirt diameter (standard):88.980-88.990 mm (3.5031-3.5035 in)
Piston pin outer diameter:19.989-19.995 mm (0.7870-0.7872 in)
Piston ring side clearance:Top0.045-0.080 mm (0.0018-0.0031 in)
Second0.030-0.070 mm (0.0012-0.0028 in)
Oil0.065-0.135 mm (0.0026-0.0053 in)
Piston ring end gap:Top0.21-0.31 mm (0.0083-0.0122 in)
Second0.32-0.47 mm (0.0126-0.0185 in)
Oil0.20-0.60 mm (0.0080-0.0240 in)
Connecting rod center distance:143.00-143.10 mm (5.63-5.63 in)
Connectin rod small end inner diameter:20.000 mm (0.7874 in)
Connectin rod big end inner diameter:48.000 mm (1.8898 in)
Crankshaft journal diameter:54.979-54.978 mm (2.1645-2.1645 in)
Crankpin diameter:44.974-44.973 mm (1.7706-1.7706 in)

CYLINDER HEAD

The engine has an aluminum cylinder head with two chain driven overhead camshafts (four valver per cylinder) and variable valve timing (CVTC) on the intake camshaft. Intake valves are 35.5 mm (1.398 in.) in diameter, intake duration is 244 °, and the exhaust valves are 30.5 mm (1.20 in.), exhaust duration is 224 °.

The QR25DE engine does not have hydraulic lifters, so special valve lifters are used to adjust the valve clearance.

Cylinder head (Before upgrade specs)
Cylinder head alloyAluminum
Cylinder head height:129.4 mm (15.09 in.)
Valve Arrangement:DOHC, chain drive
Valves:16 (4 valves per cylinder)
Intake/Exhaust duration:244/224 °
Valve head diameter:INTAKE35.5-35.8 mm (1.398-1.409 in)
EXHAUST30.5-30.8 mm (1.201-1.213 in)
Valve length:INTAKE97.16 mm (3.8252 in)
EXHAUST98.82 mm (3.8905 in)
Valve stem diameter:INTAKE5.965-5.980 mm (0.2348-0.2354 in)
EXHAUST5.955-5.970 mm (0.2344-0.2350 in)
Cam height:INTAKE45.665-45.855 mm (1.7722-1.7797 in)
EXHAUST43.975-44.165 mm (1.7313-1.7388 in)
Outer camshaft journal diameter:№127.935-27.955 mm (1.0998-1.1006 in)
№2-523.435-23.455 mm (0.9226-0.9234 in)

Head tightening procedure and torque specs:

  • Step 1: 98.1 Nm; 10 kg·m; 72 ft·lb
  • Step 2: Loosen all bolts completely
  • Step 3: 39.2 Nm; 4.0 kg·m; 29 ft·lb
  • Step 4: Turn all bolts 75°
  • Step 5: Turn all bolts 75° again

PROBLEMS AND MALFUNCTIONS

Service life of the QR25DE engine is about 120,000 miles of mileage (200,000 km). The valve clearance needs to be adjusted every 60,000 miles of mileage (90,000 km).

Frequent problems and malfunctions:

  1. Oil leaks from under the cylinder head cover. That problem fixes by installing the new gasket.
  2. Idle problems, jerking. The problem in the stretched timing chain. A new timing chain will allow you to forget about any issues related to bad timing chain.
  3. Random misfire. Fuel injectors or throttle body require cleaning.
  4. High oil consumption. If your oil consumption exceeds 1 qt. per 1500 miles (0,5L per 1000 km), then the piston rings and valve oil seals need to be replaced.

MAINTENANCE DATA

Valve clearance (HOT)
Intake valve0.32-0.40 mm (0.013-0.016 in)
Exhaust valve0.33-0.41 mm (0.013-0.016 in)
Compression pressure
Standard12.8 kg/cm2 (181 psi) / 250 rpm
Minimun10.8 kg/cm2 (154 psi) / 250 rpm
Compression differential limit between cylinders1 kg/cm2 (14 psi) / 250 rpm
Oil system
Oil consumption , L/1000 km (qt. per miles)up to 0.5 (1 qt. per 1200 miles)
Recommended engine oil5W-30, 10W-30
Oil type APISG, SH, SJ, SL
Engine oil capacity (Refill capacity)With filter change 4.2 l (4.5 qt.)
Without filter change 4.0 l (4.25 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 98 (0.98, 1.0, 14)
2,000 rpm: More than 294 (2.94, 3.0, 43)
6,000 rpm: More than 392 (3.92, 4.0, 57)
Ignition system
Spark plugStandard: PLFR5A-11 (NGK, Platinum type)
Cold: PLFR6A-11 (NGK, Platinum type)
Hot: PLFR4A-11 (NGK, Platinum type)
Spark plug gap1.1 mm (0.043 in)
Spark plug torque24.5 N·m (2.5 kg·m; 18 lb·ft)

Valve clearance adjustment data

Calculate 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 – 0.28 mm (0.011 in)]
Exhaust:
N = R + [M – 0.30 mm (0.012 in)]

Valve lifters are available in 26 sizes from 6.96 mm (0.2740 in) to 7.46 mm (0.2937 in), in steps of 0.02 mm (0.0008 in).

Example (intake valve):
R = 7.10 mm
M = 0.36 mm
N = 7.10 + (0.36 – 0.28) = 7.18 mm, so we need a valve lifter with code 718.

For adjustingFor checking
ColdHot
Intake0.24-0.32 mm (0.009-0.013 in)0.32-0.40 mm (0.013-0.016 in)
Exhaust0.26-0.34 mm (0.010-0.013 in)0.33-0.41 mm (0.013-0.016 in)

Whenever valve clearances are adjusted to cold specifications, check that the clearances satisfy hot specifications and adjust again if necessary.

Download QR25DE engine manual

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