Nissan Terrano crankcase ventilation valve: diagnostics, replacement and repair tips

Crankcase ventilation (PCV) system in Nissan Terrano - one of those components that drivers remember only when it fails. Meanwhile, faulty PCV valve can cause increased oil consumption, unstable engine operation and even serious damage to the turbine (if there is one). In this article we will look at how the crankcase ventilation valve works Terrano different generations, what symptoms indicate its malfunction, and how to correctly replace it without errors.

Feature Nissan Terrano (especially with motors K9K And MR20DD) — sensitivity to the state of the PCV system. Unlike many competitors, here the valve is integrated into the valve cover or placed separately, which complicates diagnostics. We collected data from manuals, the experience of service technicians and reviews from owners to give the most practical recommendations. Without water - only specific facts, diagrams and step-by-step instructions.

How does the crankcase ventilation system work in Nissan Terrano?

PCV system (Positive Crankcase Ventilation) in Terrano performs two key functions:

• 🔄 Crankcase gas removal from the engine to the intake manifold for afterburning in the cylinders. This reduces exhaust toxicity and prevents crankcase pressure from increasing.
• 🛢️ Protecting oil from contamination. Without ventilation, gases condense in the oil, forming sludge and accelerating wear of parts.
• ⚡ Engine stabilization. Impaired ventilation leads to a pressure imbalance, which manifests itself as floating speed or tripling.

On Nissan Terrano (depending on the year and engine) two types of systems are used:

1. Closed PCV (on most petrol versions): The valve is located in the valve cover or in the intake manifold. Gases are discharged directly into the intake manifold.
2. Semi-open PCV (on diesel K9K): some of the gases are discharged into the atmosphere through the oil separator, and some into the intake. Here the valve is often combined with an oil separator.

The key element of the system is PCV valve. It regulates the flow of gases depending on the vacuum in the intake manifold. Under high loads (for example, when overtaking), the valve opens wider, allowing more gases to pass through. At idle speed, the flow is limited so as not to disturb the composition of the fuel mixture.

Signs of a bad PCV valve on a Nissan Terrano

A faulty crankcase ventilation valve manifests itself differently depending on the nature of the failure. Let's look at typical symptoms for Terrano:

Symptom	Probable Cause	Consequences of ignoring
Increased oil consumption (up to 1 liter per 1000 km)	The valve is stuck in the open position - gases blow the oil out through the breather	Oil burn, ring jam, turbine wear (diesel)
Floating idle speed	The valve is stuck in the closed position - the vacuum in the crankcase is broken	Unstable engine operation, lambda probe errors
Oil in the intercooler or in the intake manifold	Oil separator or PCV valve is faulty (on diesel engines) K9K)	Turbine contamination, power loss, detonation
Noisy breather (whistle or hiss coming from under the valve cover)	Clogged PCV valve or hoses - gases seek an alternative outlet	Rupture of seals, extrusion of gaskets

On Nissan Terrano with motor MR20DD valve jamming in the open position is more common, which leads to oil entering the combustion chambers through the intake manifold. This causes carbon deposits on valves and spark plugs, as well as errors. P0171 (lean mixture) or P0300 (lots of misfires). On diesel K9K A typical problem is a clogged oil separator, which causes oil to be forced into the intercooler.

⚠️ Attention: If on Terrano with a mileage of more than 150 thousand km, white smoke appeared from the exhaust pipe and oil in the coolant - do not attribute this to the PCV valve. Check the cylinder head gasket urgently: these symptoms are often confused, but the consequences of the problems are different.

Diagnostics of the crankcase ventilation valve

Checking the PCV valve for Nissan Terrano can be done independently without special equipment. Here is a step-by-step algorithm:

Remove the valve (see location below)

Blow out the valve with your mouth - it should only allow air to flow in one direction

Turn the valve - if it does not rotate or rotates with difficulty, it is jammed

Inspect PCV hoses for oil and cracks.

Check the tightness of the connections (air leaks cause lambda errors) -->

The location of the valve depends on the engine model:

• 🔧 Terrano with MR20DD (2.0 petrol): The valve is integrated into the valve cover (black plastic housing with rubber seal).
• 🔧 Terrano with K9K (1.5 dCi): The valve is located in the oil separator (metal housing next to the turbine).
• 🔧 Terrano with HR16DE (1.6 petrol): the valve is located in the inlet pipe (plastic tee with a hose from the crankcase).

For accurate diagnosis you can use vacuum test:

1. Start the engine and let it warm up to operating temperature.
2. Remove the oil filler cap. If smoke comes from the neck or pressure is felt, the PCV valve is faulty.
3. Turn off the engine and place a piece of paper on the neck. If it is attracted when starting, the vacuum is normal. If not, the valve is stuck.

Selection of spare parts: original vs analogues

For Nissan Terrano original PCV valves are supplied by the company Nissan under the articles:

• 📌 11720-4M000 - for gasoline engines MR20DD And HR16DE (valve in valve cover cover).
• 📌 11720-ED000 - for diesel K9K (valve in oil separator).
• 📌 11720-JD00A — universal valve for earlier versions (before 2015).

The cost of the original is from 1,200 to 2,500 rubles. However, there are proven analogues:

Manufacturer	Article	Price, rub.	Notes
Corteco	20010007	800–1 100	Good quality, but there are fakes
Febi	20110	950–1 300	Suitable for diesel K9K
Mahle	OC 227	1 400–1 800	The best option for gasoline engines

When choosing an analogue, pay attention to:

• 🔍 Housing material: in the original it is heat-resistant (withstands up to 150°C); in cheap analogues, the plastic may become deformed.
• 🔍 Spring stiffness: If the spring is too soft, the valve will leak gases even at idle.
• 🔍 Availability of O-ring: Without it, air leaks are possible.

⚠️ Attention: On Terrano with motor K9K after 2017, a modified PCV valve with the article number was installed 11720-ED00B. It looks similar to the old version, but has a different spring calibration. Installing an old valve on a new engine will result in an error P0401 (insufficient EGR flow).

Step-by-step instructions for replacing the PCV valve

Replacing the crankcase ventilation valve with Nissan Terrano does not require special tools, but there are nuances depending on the type of engine. Let's consider the process using the example of a gasoline MR20DD:

Required tools:

• 🔧 Flathead screwdriver (for removing clamps)
• 🔧 10 mm wrench (to unscrew the valve cover on some versions)
• 🔧 New PCV valve and o-ring
• 🔧 Carburetor cleaner (for flushing hoses)

Work order:

1. Disconnect the negative terminal of the battery (to avoid ECU errors).
2. Remove the decorative engine cover (if equipped). On MR20DD it is secured with 4 latches.
3. Loosen the clamps and remove the hoses from the PCV valve. Pay attention to their condition - if the hoses are hardened or cracked, they also need to be replaced.
4. Remove the old valve from the valve cover cover. On some versions Terrano To do this, you will need to unscrew the two cover bolts (10 mm wrench).
5. Clean the valve seat from oil deposits. Use carburetor cleaner and a rag.
6. Install a new valve with O-ring. Make sure the valve is installed the correct way (there is a flow direction arrow on the body).
7. Connect the hoses and tighten the clamps. Check the connections for tightness.
8. Connect the battery and start the engine. Let it idle for 5-10 minutes, checking for air leaks.

On diesel Terrano with motor K9K the process is more complicated:

Features of replacement on diesel K9K

1. The PCV valve is integrated into the oil separator, which is attached to the cylinder block with three 13 mm allen bolts.

2. Before removing the oil separator, be sure to drain the engine oil (otherwise it will flow through the open hole).

3. After installing the new valve, check the operation of the turbine - if the PCV is faulty, the turbine blades may be oily, which will require additional cleaning.

After replacing the valve, reset the ECU adaptations. To do this:

1. Disconnect the battery for 10 minutes.
2. Start the engine and let it idle for 10-15 minutes.
3. Drive 5-10 km with smooth acceleration up to 3,000 rpm. This will allow the ECU to “learn” new ventilation parameters.

Common replacement mistakes and how to avoid them

Even experienced technicians make mistakes when working with the PCV system on Nissan Terrano. Here are the most common:

1. Installing the valve the wrong way around. There is an arrow on the valve body indicating the direction of gas flow. If you mix up the sides, the engine will run unstably and a burning smell will appear in the cabin.

   ⚠️ Attention: On diesel Terrano the arrow should be pointing from crankcase to intake manifold. On gasoline engines it’s the other way around. from manifold to crankcase (due to the difference in vacuum).

2. Ignoring the condition of the hoses. If the PCV hoses are hardened or cracked, the new valve will not last more than a month. Hoses need to be changed every 100 thousand km.
3. Incorrect tightening torque. When replacing the valve with K9K The oil separator bolts are tightened to a torque of 25 Nm. Over-tightening leads to cracks in the body.
4. Lack of ECU training. After replacing the valve, you need to reset the adaptations (see instructions above). Otherwise errors may appear P0171 or P0401.

Another typical problem is use of sealant when installing the valve into the valve cover. No sealant is needed: the O-ring provides a sufficient seal. Sealant can get into the ventilation system and clog the oil separator.

If after replacing the valve with Terrano The following symptoms appear, which means the work was done incorrectly:

• 🚨 Error P0401 (insufficient EGR flow) - the valve is installed on the wrong side or is stuck.
• 🚨 Increased idle speed (1,200–1,500 rpm) - air leaks through leaky connections.
• 🚨 Oil in the intercooler (diesel) - the oil separator is faulty or the hoses are clogged.

Prevention and increasing the service life of the PCV system

Average PCV valve life per Nissan Terrano — 80–120 thousand km. However, with proper operation, this period can be increased by 1.5–2 times. Here are the key recommendations:

• 🔄 Change oil every 7,500 km (even if the manufacturer indicates 15 thousand). Cheap oil or exceeding the interval leads to the formation of sludge, which clogs the valve.
• 🔄 Use low ash oil (according to classification Low SAPS). For diesel K9K fits Mobil 1 ESP 5W-30, for gasoline MR20DD — Liqui Moly Top Tec 4200 5W-30.
• 🔄 Flush the PCV system every 50 thousand km. To do this, remove the hoses and valve, wash them with carburetor cleaner, and the oil separator (on a diesel engine) with kerosene.
• 🔄 Monitor the oil level. If the level is constantly rising (due to fuel getting into the oil), it will accelerate PCV valve wear.

On diesel Terrano Additionally recommended:

• 🛢️ Every 30 thousand km, check the condition of the intercooler. If there is oil inside, this is a sign of a PCV or turbo problem.
• 🛢️ Clean the valve every 100 thousand km EGR. A dirty EGR valve increases the load on the PCV system.

For gasoline engines MR20DD And HR16DE there is an urgent problem with clogged throttle valve due to ingress of oil vapors. To avoid this, clean the choke every 20 thousand km with a carburetor cleaner (for example, Abro CC-220).

FAQ: Frequently asked questions about the PCV valve on Nissan Terrano

Is it possible to drive with a faulty PCV valve?

Short-term (1-2 weeks) - yes, but this is fraught with consequences:

• On gasoline engines - increased oil consumption and carbon deposits on the valves.
• On diesel engines - oil getting into the intercooler and turbine, which can damage it.
• On all engines there is a risk of squeezing out oil seals and gaskets due to increased pressure in the crankcase.

If the valve is stuck in the open position, oil consumption can reach 1 liter per 1,000 km. When the valve is closed, the risk of damage to the cylinder head gasket increases.

How to distinguish a faulty PCV valve from problems with the turbine on a diesel Terrano?

The symptoms are similar (oil in the intercooler, smoke from the exhaust), but there are key differences:

Sign	Faulty PCV	Faulty turbine
Exhaust smoke color	Gray (oil burns in the cylinders)	Black or gray (depending on the nature of the turbine failure)
Noise during operation	Whistling noise coming from under valve cover	Rumble or grinding noise from the turbine side
Intercooler oil	Yes, but in small quantities	Copious amounts of oil, often with metal shavings

For an accurate diagnosis, check the turbine shaft play: if there is any play, the problem is in the turbine. If there is no play, but there is oil in the intercooler, the PCV is to blame.

Do I need to change the oil after replacing the PCV valve?

If the oil is relatively fresh (its mileage is less than 5 thousand km), replacement is not required. However, if:

• The oil has turned black or has a burning smell,
• There are metal shavings in the oil,
• The oil level is constantly rising (due to fuel ingress),

then it is better to replace it. After installing a new PCV valve, wear products from the old valve may remain in the oil, which reduce the life of the new one.

Is it possible to clean the PCV valve instead of replacing it?

Yes, but this is a temporary solution. To clean:

1. Wash the valve in kerosene or carburetor cleaner.
2. Blow with compressed air (pressure no more than 3 bar).
3. Check the movement of the stem - if it does not move smoothly, the valve must be replaced.

Cleaning helps for 10–20 thousand km, but if the valve is worn out (for example, the rod seat is broken), cleaning is useless. On diesel Terrano Cleaning the valve without flushing the oil separator is ineffective.

What ECU errors may indicate problems with the PCV?

On Nissan Terrano PCV system malfunction is often accompanied by the following codes:

• P0171 / P0174 — lean mixture (valve stuck in open position, air leak).
• P0300 — multiple misfires (oil enters the combustion chambers).
• P0401 — insufficient EGR flow (on diesel engines, often associated with clogged oil separator).
• P0507 — high idle speed (air leak through a leaky valve).

If these errors appear along with symptoms of a faulty PCV (oil leaks, smoke), first check the crankcase ventilation system.