Many owners Nissan Note with engine CR14DE encounter a characteristic metallic clatter, which becomes louder when warming up or idling. This sound often scares car owners, making them think about serious damage, although in most cases the problem lies in a banal increase in thermal clearances of the valve mechanism. Engine CR14DE belongs to the class of units that do not have hydraulic compensators, which makes the procedure for adjusting the gaps a mandatory procedure for scheduled maintenance.
Ignoring this issue can lead not only to increased noise and vibration, but also to serious consequences for the cylinder head. Incorrectly set gaps disrupt valve timing, reduce power and can cause valve burnout. In this article we will look in detail at how to carry out diagnostics and setup yourself, what tools are needed for this, and how to avoid typical mistakes that even experienced professionals make.
Design features of the CR14DE valve mechanism
Engine CR14DE, installed on Nissan Note, is a 1.4-liter inline-four, developed in collaboration with Renault. Structurally, this unit is simple and reliable, but the absence of hydraulic pushers requires careful attention to the condition of the valve group. The gaps here are adjusted by selecting the thickness of the adjusting washers, which are installed between the camshaft cams and valve tappets.
Unlike systems with hydraulic compensators, where the gap is set automatically by oil, here the mechanical contact requires precise adjustment. Over time, the washers wear out, and the seats for them in the pushers break, which leads to a change in the nominal values. Adjusting washers are consumables, and their replacement is inevitable when a certain mileage is reached or noise occurs.
It is important to understand that a cold engine and a warm unit have different physical dimensions of the parts due to thermal expansion. That is why all measurements and calculations are carried out strictly on a cold engine, when the metal is in a stable state. Trying to make adjustments while the engine is hot will cause the gaps to become too large or too small after cooling, which will interfere with operation. gas distribution mechanism.
Necessary tools and workplace preparation
Before you begin disassembly, you must prepare the entire required set of tools. Working with valves requires high precision, so using low-quality equipment is unacceptable. You will need standard valve cover wrenches and sockets to remove the valve cover, as well as a specialized tool to remove the washers and check clearances.
- 🔧 Set of sockets and ratchet (usually 10, 12, 14 mm)
- 🔨 Hammer with rubber striker for careful removal of camshafts
- 📏 Set of feelers for measuring gaps (thickness from 0.05 to 1.0 mm)
- 🔍 Tweezers or a special magnetic grip for removing washers
Pay special attention to the probes: they should be smooth, without burrs or traces of corrosion. A crooked dipstick will give a false reading, which will lead to incorrect selection of a new washer. Also, be sure to have a clean rag and a container to drain the oil if you plan to replace the valve cover gasket. Access to the upper spark plugs will also be required for ease of cranking.
The procedure for measuring thermal gaps
The measurement procedure begins with the removal of all interfering elements: the air duct, the decorative engine cover and the valve cover. Once the cover is removed you will see the camshafts and valves. It is necessary to set the piston of the first cylinder to the top dead center (TDC) of the compression stroke. This can be done by turning the crankshaft using a special wrench by the pulley and following the marks on the camshaft sprockets.
In the TDC position of the first cylinder, the clearances of the intake and exhaust valves of this cylinder, as well as of valves located in certain phases on other cylinders, are checked. The dipstick is inserted between the end of the valve stem and the camshaft cam. It should go in with a little force, but not get stuck. If the dipstick goes in too easily or doesn't go in at all, the gap needs to be adjusted.
Remember that the clearances for intake valves and exhaust valves vary. Exhaust valves operate under harsher temperature conditions, so their clearances are usually larger. If you mix them up during assembly, this will lead to rapid wear of the cams and overheating of the engine. Record all the obtained values in a table for later calculation of the thickness of the new washers.
⚠️ Attention: Do not use force when checking gaps! If the dipstick does not fit, do not try to force it in as this may damage the gauge or scratch the valve and cam surfaces.
- Up to 50,000 km
- 50,000 - 100,000 km
- 100,000 - 150,000 km
- More than 150,000 km
Calculation of the thickness of new shims
After all the gaps are measured, the most important stage begins - calculation. The calculation formula depends on the direction in which the current gap differs from the nominal one. If the gap is larger than normal, you need a thicker washer; if it is smaller, a thinner one. The standard formula looks like this: N = V + (A - C), where N is the thickness of the new washer, V is the thickness of the old washer, A is the measured gap, C is the standard gap.
The thickness of the washers can vary in increments of 0.05 mm. On the engine CR14DE Usually washers with a thickness of 2.00 mm to 3.50 mm are used. It is very important to choose the size as accurately as possible. If you cannot find a washer of the required thickness, a deviation within 0.02-0.03 mm is allowed, but it is better to strive for the ideal. A discrepancy between the dimensions will lead to the fact that after a short time the gap will again be outside the permissible limits.
When purchasing new washers, be sure to check their markings. Sometimes the washers are marked with a number indicating their thickness in hundredths of a millimeter. For example, the marking “250” means a thickness of 2.50 mm. Don't rely on appearance, as washers may look the same but be different thicknesses due to wear or manufacturing defects.
- 📐 Always double check the calculation before ordering parts
- 🛒 Buy washers with a reserve in case of an error in the calculations
- 🧹 Clean the seats before installing new elements
☑️ Preparation for adjustment
Washer replacement procedure and engine assembly
Replacing the washers requires dismantling the camshafts. It seems complicated, but in fact the procedure is worked out and understandable. Remove the sprockets from the shafts, unscrew the bed bolts and carefully remove the shafts. It is important not to confuse the position of the intake and exhaust shafts, as well as their orientation relative to the engine. There are usually marks on the cylinder head housing indicating the installation location of each shaft.
After removing the shafts you will have access to the valve lifters. Use special tweezers or a magnet to remove the old washers. Carefully inspect their work surface. If the washers show deep marks or gouges, this is a sign that the camshaft lobes may also be worn. In this case, simply replacing the washers will not give a lasting result.
Insert the new washers with the markings facing down (if there are markings), install the lifters in place and carefully return the camshafts to the bed. The bed bolts must be tightened with a torque wrench, observing a certain sequence and tightening torque. Neglecting this rule can lead to shaft deformation and engine jamming. After assembly, do not forget to install the valve cover gasket and tighten all bolts firmly.
⚠️ Attention: Do not mix up the intake and exhaust camshafts! On the CR14DE engine they have different cam shapes and lengths. Installing it in the wrong place will make it impossible to start the engine.
What are the consequences of improperly tightening the camshaft beds?
If the bolts are not tightened correctly, the beds may become deformed, which will lead to misalignment of the camshaft. This will cause increased wear on the main shaft journals, irregular valve timing and, in the worst case, engine seizure. Always use a torque wrench and follow the tightening diagram in the service book.
Before installing new washers, apply some clean engine oil to them. This will make their installation easier and prevent scuffing in the first seconds of engine operation after starting.
Table of standard clearances and specifications of washers
For ease of perception and accuracy of calculations, a table is provided with the main parameters characteristic of the engine CR14DE. These data are reference data and should serve as a guide when carrying out work. Remember that tolerances are minimal, so measurement accuracy is critical.
| Parameter | Value (cold engine) | Note |
|---|---|---|
| Inlet valve | 0.15 - 0.25 mm | Tighter tolerance |
| Exhaust valve | 0.25 - 0.35 mm | Thermal expansion is taken into account |
| Washer thickness | 2.00 - 3.50 mm | Step change 0.05 mm |
| Bed tightening torque | 10 - 12 Nm | Tighten crosswise |
Pay special attention to the engine temperature when measuring. If the engine has been warmed up recently, allow it to cool completely to ambient temperature. Measurements at temperatures above 20°C can give a significant error, since the metal expands and the gaps will appear smaller than real ones. This is a critical point that beginners often miss in their rush to complete the renovation quickly.
Correct calculation of the thickness of the washers is the key to the durability of the valve mechanism. An error of 0.05 mm can reduce the life of parts by half.
Diagnostics and check after adjustment
After assembling the engine, it is necessary to conduct a test run. Listen to the engine at idle speed. The characteristic metallic clattering sound should disappear or become barely noticeable. If the noise remains, perhaps some of the clearances were set incorrectly, or the problem lies in other components, for example, in the timing rollers or chain tensioner.
Check the engine in different operating modes: at idle, with gentle pressure on the gas and under load. If a new strange sound appears at high speeds, this may indicate that the clearances are too small and the valves do not have time to close completely. In this case, re-diagnosis and, possibly, re-adjustment will be required.
Also pay attention to the color of the exhaust gases and fuel consumption. Incorrectly adjusted valves can lead to a lean or rich mixture, which will affect the vehicle's economy. If everything is in order, you can be sure that you have extended the life of the engine. Nissan Note and got rid of annoying noise.
- 🔊 Listen to the engine at different speeds
- ⛽ Monitor your fuel consumption after repairs
- 🚗 Test drive at different speeds
Frequently asked questions (FAQ)
How often do valves on a Nissan Note 1.4 need to be adjusted?
It is recommended to check clearances every 90,000 - 100,000 km. However, if you hear unusual noise or the engine is running rough, it should be checked immediately, regardless of mileage.
Is it possible to adjust the valves without removing the camshafts?
No, on a CR14DE engine, adjusting the shims requires access to the pushrods, which is only possible after removing the camshafts. An attempt at adjustment without dismantling the shafts is structurally impossible.
What happens if the gaps are too small?
Small clearances result in the valves not closing completely when heated. This causes burnt valves, loss of compression, decreased power and increased fuel consumption. In the worst case, the valve may become stuck in its seat.
Do I need to change the valve cover gasket?
Definitely yes. The old gasket almost always loses its seal after removing the cover. Using a new gasket ensures that there is no oil leakage or dirt getting inside the engine.