Characteristics
| Characteristics | QR25DE |
|---|---|
| Manufacturing | Yokohama Plant, Nissan Decherd Powertrain Plant |
| Engine brand | QR25DE |
| Years of production | 2001-present |
| Cylinder block material | Aluminum |
| Power system | Injector |
| Type | Ready |
| Number of cylinders | 4 |
| Valves per cylinder | 4 |
| Piston stroke, mm | 100 |
| Cylinder diameter, mm | 89 |
| Compression ratio | 9.1, 9.5, 10.5 |
| Engine displacement, cc | 2488 |
| Engine power, hp/rpm | 152/5200, 160/5600, 173/6000, 178/6000, 182/6000, 200/6600, 250/5600 |
| Torque, Nm/rpm | 245/4400, 240/4000, 234/4000, 244/4000, 244/4000, 244/5200, 329/3600 |
| Environmental norms | Euro 3/4 |
| Fuel consumption, l/100 km (Sentra SE-R) | City: 13.0, Highway: 8.4, Mixed: 10.7 |
| Oil consumption, g/1000 km | Up to 500 |
| Engine oil | 5W-30, 5W-40 |
| Engine oil volume, l | 5.1 |
| Oil change is carried out, km | 15000 (better 7500) |
| Engine operating temperature, deg. | ~90 |
| Engine life, thousand km | Factory data: n.a.d. |
| In practice: 200+ | |
| Tuning | Potential: 250+ |
| No loss of life: ~200 | |
| Installed in vehicles | Nissan Altima 3 (L31) 2001-2006, Altima 4 (L32) 2006-2013, Altima 5 (L33) 2012-2018, Bassara 1 (JU30) 2000-2003, Caravan 4 (E25) 2007-2012, Caravan 5 (E26) 2012-present, Frontier 2 (D40) 2004-2021, Frontier 3 (D41) 2014-present, Murano 1 (Z50) 2002-2007, Murano 2 (Z51) 2007-2014, Presage 1 (U30) 2001-2003, Presage 2 (U31) 2003-2009, Rogue 1 (S35) 2007-2015, Rogue 2 (T32) 2013-2020, Sentra 5 (B15) 2001-2006, Sentra 6 (B16) 2006-2012, Serena 2 (C24) 2001-2005, Elgrand 3 (E52) 2010-n.y., Teana 2 (J32) 2008-2013, Teana |
Faults and repair of the engine QR25DE
The engine is an ordinary QR20DE, in which was installed a crankshaft with a stroke of 100mm piston, instead of the previous 80.3mm, on shortened connecting rods, it allowed without boring to increase the volume to 2.5 liters, the exhaust camshaft was also replaced. Generally speaking, this approach of increasing the working volume makes the motor more low, tractive, at the same time, there are increased loads on the cylinder itself, and on the piston, rings and connecting rod, friction increases, temperature rises, lubrication conditions are reduced. The reason for all these phenomena is the greater angle of inclination of the short connecting rod. On the motor QR25DE such things are not mass character, but have a place, its resource is lower than its two-liter counterpart and the problem of oil burn is much more common. After 2007, the motor was corrected, the intake receiver was changed, the pistons were changed, there were reinforced connecting rods, slightly moved the balancing system, slightly changed camshafts and other less significant innovations.
For Nissan Examples P12 there was a version with direct injection QR25DD and with increased to 10.7 compression ratio.
Since 2014, the QR25DER engine was produced, which was squeezed to a compression ratio of 9.1, installed a compressor and added an electric motor for 20 hp. In total, it gave 250 hp at 5600 rpm and torque of 329 Nm at 3600 rpm.
Reliability of the QR25DE engine
The QR25DE engine is rather famous for its unreliability – too many troubles it gave and gives. We will now talk about all its weak points.
However, the engine of the sample of 2007 is better. And here we will mention that in February this year in the USA found a Nissan Frontier pickup truck (aka Navara), which has passed a million miles and continues to drive on. It was reported that the 2.5-liter engine under its hood had not undergone any repairs, except for the replacement of the chain at the turn of 700,000 miles. And oil changes were performed every 10,000 miles.
Overheating
A common problem with the QR25DE engine is overheating. Overheating usually happens because of a clogged radiator, either on the outside or inside. Diligent people have even devised a method of flattening the radiator to clean its channels.
Engine overheating is also caused by problems with the thermostat. The engine reacts to overheating by deformation of the cylinder-head, gasket breakdown and oil rings clogging.
Catalyst
The exhaust system of the QR25DE engine is equipped with a two-stage catalytic converter. The pre-catalyst is located literally in the intake pipe. In the early years of production, this catalyst had ceramic honeycombs, which quickly clogged. Strongly clogged ceramic catalyst began to dust ceramic dust, which got into the cylinders and led to the appearance of scoring on their surfaces. As the scoring occurred, the QR25DE motor began to consume oil.
Ceramic catalytic converters on motors manufactured before 2005 were replaced with metal honeycomb catalytic converters. Scuffed engines were also changed.
The metal catalytic converter can also dust metallic powder when plugged and melted, which happens due to the use of poor quality oil and fuel.
Crankshaft Position Sensor (CPPS)
QR25DE engines manufactured before 2006 had a bad crankshaft position sensor with a plastic housing. These sensors would quickly begin to glitch due to oil leaking through their housing into the electrical connector. In the case of such a failure, the signal from the sensor is briefly lost, and the engine starts badly, stalls on the move when braking, also after starting the tachometer arrow does not rise.
When the sensor is worn out, the engine starts badly on hot, can be dull after shifting gears, the engine speed can hang up. There is also an error indicating a faulty crankshaft sensor.
Improved version of the crankshaft position sensor has a metal bulb, does not leak oil, but long life is not distinguished.
Camshaft position sensor
The camshaft position sensor also often glitches, with an error appearing on it, and the engine starts very badly.
Throttle valve
The throttle valve of the QR25DE engine is quite capricious. It happened that on brand-new cars, the warmed engine after starting stalled as a result of floating revolutions. In this regard, the instruction manual says that for a successful start the engine should be started with the accelerator pedal depressed.
You can get rid of unstable idling by cleaning the throttle valve and its adaptation. Adaptation can be done without special devices by a special algorithm with the accelerator pedal.
If the throttle plate is quickly and abundantly polluted with oil and soot, the engine has problems with oil consumption. That is, too much oil vapor is getting into the intake through the crankcase ventilation system.
You can choose and buy a throttle valve for Nissan engine in our catalog of contract parts.
Inlet manifold flaps
The intake manifold of the QR25DE engine is equipped with flaps that reduce the cross-section of the intake channels (there are no such flaps on the 2-liter QR20DE). These are not “vortex flaps”, as they do not cover half of the intake channels. However, by reducing the cross-section of the intake passages, the intake air flow is accelerated for better fuel mixing in the cylinders.
These flaps on the 2.5-liter QR25DE motor caused a lot of trouble. Due to weak screws holding the flaps to their axle, they would break off and fly toward the intake valves. In many cases, the flaps got caught under the valves, causing damage to the valves.
You can choose and buy an intake manifold for Nissan engine in our catalog of contract parts.
Thermostat
The thermostat on the QR25DE engine is located in the cylinder block. And in the cooling system tee located on the cylinder head there is a distributor valve. This is essentially also a thermostat that opens when it gets hot to 95°. Until it is open, there is no circulation of coolant in the cooling jacket of the cylinder block. This is done so that the engine warms up faster.
But because of this solution, the joint between the permanently cooled cylinder head and the cylinder block experiences a temperature difference, which in the long run leads to the penetration of the cylinder head gasket. In addition, due to the sufficiently high temperature of the block there are conditions for sticking oil rings. And if the thermostat-distributor jams, the engine will successfully overheat – at least the cylinder block will “lift” the cylinder head. In practice, owners remove the thermostat from the distributor. The risk of overheating is reduced, and the “heater” begins to heat the car interior faster.
Glands of spark plug wells
Rubber oil seals of plug wells on the QR25DE motor are soldered into the plastic valve cover. Over time, they harden, lose elasticity, crumble, after which oil gets into the wells of spark plugs. Original oil seals are not sold separately as they are part of the valve cover. An original new valve cover costs about $200.
But there are already non-original spark plug well oil seals for this motor. A few years ago, handymen picked up non-original oil seals from Honda D- and F-series motors to replace these seals. To replace them, the old oil seals have to be literally uprooted: knocked out, cut out.
You can choose and buy a valve cover for Nissan engine in our catalog of contract parts.
Gas timing clutch
The QR25DE engine phase shifter and its control solenoid valve serve well and usually do not cause any problems. If there are errors in the operation of the timing system, if the clutch shoots after starting, it is necessary to clean the clutch, the valve, as well as the oil intake. Most likely, particles of burnt oil have collected in these units and in the oil system as a whole.
Chain stretching
The timing chain on the QR25DE engine may require replacement at a mileage of 100,000 to 200,000 km. In some cases, the timing chain makes noise after starting the engine, you may even hear a grinding noise when starting the engine and during acceleration.
But in most cases, the stretched chain behaves quietly. But at the same time, fuel consumption increases noticeably, the engine becomes sluggish, may twitch during acceleration. All this happens because of the lag of camshafts from the crankshaft. Namely because of the remaining phase of overlapping of intake and exhaust valves.
All this ugliness can be seen by the unsynchronization of signals from the crankshaft and camshaft sensors.
To replace the timing chain buy the timing chain, balancer chain, all the guides, hydraulic tensioner, crankshaft pinion and exhaust camshaft pinion.
Signs of improper thermal clearances
Nissan QR-series motors do not have hydrocompensators. When running on gasoline, the thermal clearances remain nominal for quite some time. The clearances for intake valves on a cold engine: 0.24-0.32 mm, for exhaust valves – 0.26-0.34 mm.
When running on gas, the thermal clearances of the exhaust valves decrease rather quickly, so it is necessary to check them every 50,000 km.
If you miss this moment, then because of “clamped” exhaust valves, the cold engine noticeably loses power, may stall when starting or braking. All these symptoms disappear when the engine is heated to operating temperature. In especially neglected cases with clamped or moving exhaust valves, the engine starts badly on cold, strongly troits, stalls at the slightest increase in load.
Adjustment of valves is made in the most inconvenient way: selection or grinding of calibrated tappets. In this case, after measuring the existing clearances, it is necessary to remove both camshafts.
You can choose and buy a cylinder head (Cylinder Block Head) for Nissan engine in our catalog of contract parts.
Oil flow through the oil caps
The temperature regime of the QR25DE engine can not be called gentle, so by 10 years of operation in the cylinder head of this power unit, the oil caps harden. As a result, the engine begins to consume oil flowing into the combustion chambers through the valves. Oil consumption by this “source” can reach 300 grams per 1000 km. In general, replacement of oil caps is necessary in any overhaul of this motor.
Breaking of the cylinder-head gasket
Breakdown of the cylinder-head gasket or violation of the geometry of the cylinder-head is not a rare problem of the QR25DE engine, which occurs due to engine overheating.
Usually after that, the level of antifreeze in the cooling system decreases, which either gets into the cylinders or into the lubrication channels, and from there into the oil pan. When the engine is running, gas bubbles may appear in the cooling system and in its expansion tank.
Cylinder Block Roughing
Sometimes in the cylinder block of overheated QR25DE engines there are cracks in the walls between neighboring cylinders.
Oil burn through the cylinder piston group
The 2.5-liter Nissan engine starts to eat oil sooner than the smaller 2-liter engine. The pistons have all the “data” for this: thin piston rings, lack of oil drain holes. Low-quality or too viscous oil, as well as overheating of the pistons – all of this quickly leads to sticking and seizure of oil rings. If the engine has not had time to swallow dust from the destroyed catalytic converter, the surface of the cylinders does not wear. Therefore, the QR25DE engine can be restored by replacing the pistons and rings.
Tuning the engine QR25DE
Chip tuning and atmo
This motor in the standard gives out 177 hp, but on our cars (Teana, Murano, X-Trail) the motor is strangled to ~170 hp, you can flash, knock out the catalytic converter and get about 10 hp on top, but it is so trivial… It will be more original to make a cold air intake, to put camshafts from Nissan Sentra SE-R Spec V, there is the same QR25DE, but with a little more evil shafts, they will allow to spin the motor up to 7000 rpm (instead of 6100 in the stock), together with them we will put a straight-through exhaust with a 4-2-1 exhaust manifold. These dances will allow to raise the output to ~190 hp and get a motor with a more sporty character. If you remove the balancer shafts, you can remove about 10 more hp.
QR25DE turbo / QR25DET
On our 2.5 liter motor there are not a few turbo kits, mostly based on Garrett T3, this will be enough for us. We order a complete kit, intercooler, injectors 440cc from Subaru WRX, Fuel pump Walbro GSS342, exhaust at least 63 mm pipe, customize. We’ll leave the stock piston rod, we’ll limit the pressure by 0.5 bar, it will give about 220 hp. The standard piston is not designed for supercharging and the motor can fall apart at any moment. To get a reliable turbo motor, or to remove more power, it is necessary to order forged piston for low compression ratio, about 8.5. After replacing the piston, you can blow full throttle for 300+ hp.
ENGINE RATING: 4-