Engine QR20DE has become a real pillar of reliability for the line of crossovers Nissan X-Trail first and second generation. However, even such time-tested units have their weak points, among which the gas distribution system occupies a special place. Chain stretch or wear of the dampers inevitably leads to the need for a complex procedure to replace them, where the correct setting of the valve timing becomes a critical step.
Many car owners and even service center technicians underestimate the importance of precise shaft synchronization, believing that simply aligning the gear teeth is enough. In fact, the motor QR20DE has a specific marking system that requires attention to detail and an understanding of the operating principles of the hydraulic tensioner. A mistake of even one tooth can lead to serious consequences, including valves meeting pistons and costly major repairs.
Design features of the timing drive on the QR20DE
Engine gas distribution system QR20DE built according to the classic design with one long chain that drives both the intake and exhaust camshafts. A special feature of this engine is the absence of traditional “sprockets” with slots, which are familiar to many other Japanese engines. Instead, the manufacturer used specific colored chain links and precise grooves on the shaft sprockets.
The main element defining the phases is camshaft sprocket, which has a unique marking. It is important to understand that the chain here is not just tensioned, it works in tandem with the VVT (variable valve timing) system on the intake shaft. This means that the hydraulic clutch must be set in a specific position, otherwise the engine electronics will not be able to control the advance angle correctly.
When removing the chain you will notice that the guides are made of plastic and tend to break down at high mileage. Plastic fragments can get into the oil channel, which often causes tensioner failure. Therefore, when replacing a chain, it is strongly recommended to completely clean the oil channels and replace all guides, not just worn ones.
Location and identification of timing marks
The main difficulty when working with the motor QR20DE is that the marks are not always obvious and can be erased by time or paint. The exhaust camshaft sprocket (on the right, when viewed from the alternator belt side) should be clearly visible mark in the form of a triangle or dot, which aligns with the corresponding protrusion on the bearing housing or cylinder block.
On the intake camshaft sprocket (left), the situation is more complicated due to the presence of a phase shifter. Here the mark should coincide with the mark on the phase shifter body. However, the most important reference point is the chain itself. Manufacturers use colored links: usually these are golden or red a link that must be installed strictly opposite the mark on the intake shaft sprocket.
Don't forget the crankshaft. There is also a mark on its sprocket, which should coincide with a notch on the oil pump housing or cylinder block. Often this mark has to be cleaned with a brush, as it becomes clogged with dirt and carbon deposits. Without a clear alignment of all three points (crankshaft, intake shaft, exhaust shaft), starting the engine will be impossible or it will run with strong misfires.
Preparing the engine for chain removal
Before starting work, it is necessary to ensure access to the front of the engine. This will require removing the plastic covers, the alternator belt and, in some cases, the right fender liner. You will also need to remove the crankshaft pulley, for which you need to secure the shaft from turning. This is done using a special tool or insertion through the spark plug hole method, but be extremely careful not to damage the piston.
Pay special attention to draining the coolant and oil. If you plan to remove the oil pump along with the front cover, then draining the oil is mandatory. As you work, you will need to access the bottom of the sump to unscrew the pump mounts. Make sure you have a container to catch any leaked technical fluids.
Before unscrewing the camshaft gears, be sure to secure the shafts with a wrench so that they do not rotate under the action of the phase shifter springs. If this is not done, the spring may suddenly spring back, damaging the gear or causing injury to the operator. Use the keys on 24 mm for gears and 10 mm or 12 mm for fixing shafts.
☑️ Preparation for timing belt removal
The process of installing a new chain and aligning marks
Installing a new chain requires maximum precision. The first step is to install the chain on the crankshaft sprocket, with the colored link located at the bottom. Then, after passing the chain through the tensioner and dampers, it is put on the exhaust camshaft sprocket. The mark on the chain (usually one colored link) must clearly coincide with the mark on the sprocket.
The next step is to tension the chain to the intake camshaft sprocket. It is important to remember about the phase shifter here. It must be set to the "closed" or neutral position before installation, otherwise synchronization problems may occur when first run. The colored link on the chain should match the mark on the intake gear. It is critical to check that the chain is not twisted and that all guides are level on the guides.
After putting the chain on all the gears, you need to make sure that all the marks match. The crankshaft should be aligned with the mark on the block, the exhaust shaft with the mark on the body, and the intake shaft with the mark on the phase shifter. Only when all three indicators completely coincide can the gear bolts be tightened. Use a torque wrench to maintain the tightening torque, usually 90 Nm plus the rotation angle, but it’s better to check the manual.
- Up to 100,000 km
- 100,000 - 200,000 km
- More than 200,000 km
- I don't know the exact mileage
Installing the tensioner and checking the operation of the system
The hydraulic chain tensioner is a mechanism that operates under oil pressure. Before installing a new tensioner, it must be unlocked. Depending on the type of tensioner (old or new), the procedure may differ: in some cases you just need to press the rod and secure it with a locking pin, in others you need to press the lever all the way. Be sure to remove the stopper before final installation into the engine.
After installing the tensioner and assembling all the timing cover elements, you must manually turn the engine crankshaft two full turns. This action is necessary to ensure that the pistons do not meet the valves and the chain does not fly off. When cranking, listen carefully to the engine: there should be no extraneous knocks, squeaks or jamming.
If after two revolutions all the marks match perfectly again, it means the job was done correctly. If the marks are lost, the procedure must be repeated again. This is a common mistake that inexperienced mechanics make when trying to save time and not cranking the engine before starting. Never start the engine immediately after assembly without checking the alignment of the marks manually!
| element | Tag type | Alignment position | Special Notes |
|---|---|---|---|
| Crankshaft | Recess on the body | Top dead center | Check through the cylinder block window |
| Exhaust shaft | Point/Triangle | Bearing housing | Usually the right sprocket |
| Intake shaft | Colored chain link | Mark on the phase shifter | Check VVT position |
| Chain | Gold/Red link | On both stars | There must be one link between the marks |
Typical mistakes and common problems
One of the most common mistakes is incorrect installation of the hydraulic tensioner. If you do not remove the locking pin or press the rod all the way, the chain will remain loose. This will lead to a characteristic metallic ringing sound on a cold engine, which may disappear after warming up, but indicates a serious problem.
⚠️ Attention: If you hear a chain ringing when cold, which disappears after 10-15 seconds of operation, this is a sure sign that the tensioner has not worked or there is air in it. In this case, the engine must be turned off immediately to avoid the chain jumping onto a tooth or more serious damage.
Another problem is the use of low quality non-original spare parts. Chain stabilizers on QR20DE often made of plastic, which crumbles over time. Cheap analogs may have incorrect geometry, which leads to chain misalignment and rapid wear of new sprockets. Also, cheap chains may have incorrect pitch, which leads to noise and rapid stretching.
Often, craftsmen forget to replace the O-rings and gaskets when assembling the timing cover. This results in oil leaks that can drip onto the hot exhaust manifold, causing a burning smell and even a fire. Always use a set of new gaskets and high temperature sealant to seal the joints.
What if the labels don't match after scrolling?
If after two revolutions of the crankshaft the marks do not coincide, it means that the chain has jumped one or more teeth. You will have to remove the timing cover again, reset the tension and reposition the chain. Sometimes the problem lies in worn sprockets, which “eat up” the chain pitch. In this case, replacing only the chain will not help; the camshaft sprockets also need to be changed.
Check and final assembly
After successfully checking the marks, you can begin the final assembly. Install the crankshaft pulley, making sure the key or groove lines up. Tighten the pulley bolt to the recommended torque. Next, install the alternator belt, tensioner and all dismantled body parts and attachments.
Fill with new engine oil and coolant. Start the engine and let it idle. Listen to the sounds of the timing belt: it should be smooth, without extraneous noise. Check for oil leaks from under the timing cover. If everything is in order, you can do a test run and check the engine operation under load.
Do not forget to reset errors if they appeared in the ECU memory during diagnostics. Use an OBD2 scanner to check the data from the valve timing sensors. The valve opening angle readings should be within normal limits. If the engine runs unevenly or the “Check Engine” light is on, errors may have been made during installation when working with the phase shifter.
When purchasing a timing kit, always choose genuine Nissan parts or trusted brands (e.g. Gates, Dayco). Saving on a chain drive can cost many times more during subsequent engine repairs.
Bottom line: The success of replacing a chain on a QR20DE is 90% dependent on accurately aligning the colored chain links with the markings on the sprockets and checking the alignment after two revolutions of the crankshaft by hand.
⚠️ Attention: On engines with mileage of more than 200,000 km, camshaft sprockets often have worn out teeth. If you put a new chain on old sprockets, it will quickly stretch again. Always inspect the sprockets for any sharp teeth and replace them as a chain set if necessary.
FAQ: Frequently asked questions about the timing belt on the Nissan X-Trail
How often should the timing chain be replaced on a QR20DE?
Officially, the manufacturer claims an “eternal” chain, but in practice the resource ranges from 150,000 to 250,000 km. It depends on the quality of the oil, driving style and operating conditions. If circuit noise or phase errors occur, replacement must be carried out immediately.
Is it possible to change the timing chain without removing the engine?
Yes, on the Nissan X-Trail the timing chain is replaced “on site” without removing the engine. However, the right engine mount will need to be removed and the crankshaft pulley removed, which can be difficult in a cramped engine compartment.
What happens if the labels are mixed up during installation?
If the marks are installed incorrectly, the engine may not start, run rough, lose power, or, worst of all, the valves meet the pistons, which will lead to a major engine overhaul.
Do I need to change the hydraulic tensioner when replacing the chain?
It is strongly recommended to change the tensioner together with the chain. The old tensioner may have wear on the mechanism or become jammed, which will negate all efforts to install a new chain. This is a small part, but critical for reliability.
How to check that the marks match without disassembling?
Without disassembling it is impossible to verify an exact match. You can only evaluate indirect signs: the absence of phase errors, smooth engine operation. But to be completely sure, you need to remove the timing cover and visually verify that the colored links and marks match.