The crankcase ventilation system is one of the key elements in the operation of any internal combustion engine, and Nissan Almera Classic with its G15 series units there is no exception. It is on the serviceability of this system that not only the stability of the engine at idle speed depends, but also the durability of the piston group, as well as the cleanliness of the oil. When you notice that the engine begins to “trouble” or fuel consumption increases unnoticed, often the problem lies precisely in the operation of the valve.
Many owners Nissan Almera Classic They ignore the first signals about problems with crankcase gases, attributing everything to the need to replace spark plugs or filters. However, clogged or jammed crankcase valve creates excess pressure inside the crankcase, which leads to squeezing out oil seals and oil leaks. Understanding how this part works will help you avoid costly engine repairs in the future.
In this article, we will analyze in detail how the ventilation system functions on this model, what symptoms indicate a failure of the unit, and how to replace it yourself, saving money on service.
The principle of operation of the crankcase ventilation system on Nissan Almera Classic
In engines of the G15 family installed on Nissan Almera Classic, a positive crankcase ventilation (PCV) system is used. The main task of this system is to divert gases escaping from the combustion chamber into the crankcase back into the intake manifold for afterburning. This allows you to maintain internal pressure at atmospheric levels and prevent contamination of the oil with combustion products.
The process is regulated crankcase gas valve (PCV valve), which opens and closes depending on the vacuum in the intake manifold. When you are idling, the vacuum is high and the valve allows a certain amount of gases to pass through. Under load, the vacuum drops and the valve capacity changes to ensure optimal mixture formation.
If PCV valve gets stuck in the open position, the engine begins to “grab” excess air, which leads to a lean mixture and unstable speed. When stuck in the closed position, the pressure in the crankcase increases, squeezing oil through the crankshaft and camshaft seals, as well as through the gasket seals.
It is important to understand that Nissan Almera Classic the ventilation system is integrated into the valve cover and connected to the intake manifold. This makes replacement easier than some other models where the valve is located in hard to reach areas.
The main symptoms of a malfunctioning crankcase gas valve
Determine the fault crankcase valve can be based on a number of characteristic symptoms that appear during the operation of the car. Ignoring these signs can lead to serious consequences, so diagnosis should be carried out regularly.
The very first and most noticeable sign is often unstable engine idling. The tachometer needle may begin to float, and the engine itself may vibrate slightly. This happens because ventilation system allows excess air to pass through, disrupting the air-fuel mixture.
- 🔍 Increased oil consumption without visible external leaks
- 🔊 The appearance of a whistle or hissing from under the hood when the engine is running
- ⛽ Increased fuel consumption with the same driving style
- 💨 The appearance of bluish smoke from the exhaust pipe at idle speed
Another warning sign is oil leaks. If you see that the crankshaft seal or valve cover is coated with fresh oil, but there is no other reason for the leak, the problem is most likely excess crankcase gas pressure. Crankcase pressure has no way out and looks for weak spots in the seals.
It is also worth paying attention to the operation of the ignition system. Oil mist entering the combustion chamber can quickly foul the spark plugs, leading to misfires and loss of power. If you recently changed the spark plugs and the problem returns, check the condition of the valve.
⚠️ Attention: If you notice oil deposits on the intake manifold and throttle body, this is a sure sign that oil separator in the ventilation system has ceased to cope with its task, and the valve requires replacement.
Diagnostics and testing of node functionality
Before you run to the store for spare parts, you should make sure that there is a malfunction. Diagnostics crankcase valve on Nissan Almera Classic does not require complex equipment and can be carried out independently in 15-20 minutes.
The easiest way to check is the “by ear” and “by touch” method. With the engine running at idle, remove the dipstick and try holding a piece of paper near the hole. If the paper is pressed tightly against the hole, it means that the pressure in the crankcase is too high and the valve does not allow gases to pass through. If the paper is sucked out, the system is working normally.
Another method involves removing the valve itself. To do this, you need to disconnect the pipe coming from the intake manifold to the valve cover. You need to blow through the hole in the lid or the valve itself (if it is removable). The air must pass with a certain resistance. If air flows freely like through a pipe, the valve is stuck in the open position. If it doesn’t go through at all, it’s closed.
- 🛠️ Use a flashlight to visually inspect internal cavities
- 📏 Check the pipes for cracks and oil leaks
- 🧽 Clean the holes from carbon deposits before installing a new unit
You can also check the operation of the valve by sound. With the pipe removed, place your ear close to the hole. You should hear a characteristic hiss of intake air. The absence of sound when the engine is running indicates that the system is completely inoperable.
- Every maintenance
- Once a year
- Never checked
- Only when problems arise
Selection of spare parts and design features
When choosing a replacement for Nissan Almera Classic It is important to understand that this model often uses not a separate valve, but a complex assembly that includes an oil separator and a valve diaphragm. Manufacturers offer both original parts and high-quality analogues.
Original spare part from Nissan has an article number that varies depending on the year of manufacture and engine type, but is most often found under the number 13262-AX000 or its modifications. Such valves are distinguished by high quality membrane materials and precise adjustment of the flow capacity.
Analogues from well-known brands such as Febi, Sakura or Patron, may also be suitable, but their resource may be lower. Cheap Chinese copies often have incorrect membrane rigidity, which leads to repeated failure after just a few thousand kilometers.
| Manufacturer | Part type | Average cost | Resource |
|---|---|---|---|
| Nissan (Original) | Valve assembly | 3500 - 5000 rub. | 150+ thousand km |
| Febi Bilstein | Valve/Separator | 1500 - 2500 rub. | 80-100 thousand km |
| Sakura | Analogue | 800 - 1200 rub. | 40-60 thousand km |
| Patron | Budget analogue | 600 - 900 rub. | 30-50 thousand km |
Please note that sometimes sellers offer only the valve itself, without the separator body. On Almera Classic It is better to change the entire assembly, since the separator becomes clogged with sludge over time, and even a new valve will not be able to work effectively in a dirty body.
⚠️ Warning: Do not attempt to repair an old valve by cleaning it with solvent. The membrane inside has microcracks that are not visible to the eye, and after washing it will quickly lose its tightness, which will lead to new problems.
Before purchasing, be sure to check the catalog number of the spare part with the VIN code of your car, since for 1.5 l and 1.6 l engines (if one was in the line) there may be differences in the mounting and shape of the pipe.
Step-by-step instructions for replacing the crankcase gas valve
Replacement crankcase valve on Nissan Almera Classic - a procedure of medium complexity that can be performed in a garage. You'll need a set of wrenches, a new gasket, and possibly some intake tract cleaner.
First you need to open the hood and remove the decorative plastic engine cover. To do this, simply pull it up, as it is held on by plastic clips. This will give you access to the valve cover and ventilation system pipes.
Locate the pipe connecting the valve cover to the intake manifold. It is usually located at the top of the engine. Loosen the clamp securing the pipe and carefully remove it from the fitting. Be prepared for some oil to leak out of the hole, so use a rag.
- 🔧 Unscrew the valve mounting bolts (usually there are two or three)
- 🧹 Remove old sealant and dirt from the surface of the lid
- 🛠️ Install a new gasket and secure the valve
- 🔩 Tighten the pipe clamp firmly to avoid air leaks
Install the new valve into place using a new gasket. Be careful not to overtighten the bolts, as the valve body or cover may be made of aluminum and become easily deformed. After this, connect the pipe and tighten the clamp.
☑️ Preparation for valve replacement
⚠️ Attention: If you install a valve without a gasket or with a damaged gasket, the engine will suck in excess air, which will lead to mixture errors and unstable operation. Always use a new gasket!
Proper installation of the blow-by valve is critical to system integrity. Even the slightest air leak through leaks at the valve installation site will negate all diagnostic and repair efforts.
Additional measures and prevention
Replacing the valve is not the only step you can take to improve the performance of your ventilation system. Often the problem lies in clogged pipes or a faulty oil separator, which is part of this unit.
It is recommended to regularly check the condition of the oil separator. If you frequently drive short distances or in stop-and-go traffic, condensation and unburned fuel accumulate in the crankcase more quickly, forming emulsion and sludge. This accelerates wear on the valve diaphragm.
Use quality motor oil that meets specifications Nissan. Cheap oils often have low volatility, which leads to increased carbon formation inside the ventilation system. Also monitor the condition of the ignition system, as misfires increase the amount of unburned fuel in the crankcase.
If you notice that the problem persists after replacing the valve, check the intake manifold for blockages. On Almera Classic it can accumulate a layer of oil and carbon deposits, which makes it difficult for gases to pass through even with a working valve. In this case, professional cleaning will be required.
DIY intake manifold cleaning
To clean the collector it must be removed. This requires disconnecting the throttle body, coolant pipes and sensors. After removal, the collector is cleaned with carb cleaner and a brush, special attention is paid to the ventilation channels. The process is labor-intensive but effective.
Don't forget about periodic diagnostics. Once every 30-40 thousand kilometers, it is useful to inspect the ventilation system pipes for cracks and traces of oil. Early detection of problems will help avoid serious engine damage.
Frequently asked questions (FAQ)
Is it possible to drive with a faulty crankcase valve?
Technically possible, but highly undesirable. Driving with a faulty valve leads to increased oil consumption, contamination of the intake system, unstable engine operation and, in the worst case, to squeezing out oil seals and serious oil leaks.
How often do you need to change the crankcase gas valve on a Nissan Almera Classic?
There are no official replacement regulations, but the service life of the unit is usually about 100-150 thousand kilometers. However, if you use low-quality oil or frequently drive in difficult conditions, replacement may be required earlier, already at 60-80 thousand kilometers.
What happens if you forget to install the gasket when replacing the valve?
The engine will begin to suck in unaccounted air through the leak. This will lead to a lean fuel mixture, failures during acceleration, floating idle speed and, possibly, the Check Engine light coming on.
Is it possible to flush the old valve instead of replacing it?
Flushing may temporarily improve the situation if the valve is simply stuck due to dirt, but it will not restore the elasticity of the membrane. If the membrane has microcracks, washing will not help and the problem will return very quickly.
Where is the crankcase gas valve located on Nissan Almera Classic?
The valve is located on the engine valve cover on the right side (when viewed in the direction of travel). It is connected to a pipe that goes to the intake manifold. It can be accessed after removing the plastic engine casing.