Thermostat in Nissan Almera G15 - a small but critical part of the cooling system, on which the stability of the engine depends. Its malfunction leads to overheating, increased fuel consumption, or, conversely, to prolonged warm-up of the engine in cold weather. Owners Almera G15 (especially with engines HR16DE And K4M) often encounter thermostat problems after 80–100 thousand kilometers, but not everyone is able to recognize them at an early stage.

In this article we will look at how check the thermostat on Almera G15 without removing what signs indicate its failure, and how to replace it yourself - taking into account the nuances of the design and typical mistakes. We will also provide current articles of original and analog thermostats, which are suitable for different model years (2012–2019). If you notice that the engine temperature gauge is unstable or the heater is blowing cold air, this information will help you save on diagnostics at the service center.

Signs of a thermostat malfunction on Almera G15

Thermostat Almera G15 should open at temperature 82–88°C (depending on the version), ensuring the circulation of antifreeze in a large circle. If it gets stuck in the closed or open position, the consequences will vary from increased engine wear to the risk of overheating. Pay attention to these symptoms:

  • 🔥 Engine overheating: the temperature arrow on the dashboard rises above normal (especially in traffic jams), the cooling fan turns on. At the same time, the radiator remains cold - this is a sign that the thermostat stuck in closed position.
  • ❄️ Long engine warm-up: in cold weather, the engine takes longer to warm up for 10–15 minutes, and the heater blows barely warm air. The thermostat is probably stuck open and the antifreeze is constantly circulating in a large circle.
  • 📉 Unstable temperature: the arrow on the tidy “jumps” (it rises and then falls) - this indicates incomplete opening/closing of the thermostat valve.
  • 💧 Antifreeze leak: If the thermostat starts to “sweat” or there are traces of coolant underneath it, the O-ring is worn out and the part needs to be replaced.

On Almera G15 with engine HR16DE jamming in the open position is more common (the machine takes a long time to heat up), and on K4M - closed (risk of overheating). This is due to the design of cooling systems and the location of the thermostat. If you ignore the problem, the consequences can be serious: from cracks in the cylinder head to the destruction of the cylinder head gasket.

⚠️ Attention: On Almera G15 2016–2019 production years, the thermostat is integrated into the housing with a temperature sensor. When replacing, it is important not to damage the sensor connector - otherwise the dashboard will light up. Check Engine.
📊 How often do you check the cooling system of your car?
  • Every season
  • Once a year
  • Only when problems arise
  • Never checked

How to check the thermostat on Almera G15 without removing it

You can carry out diagnostics yourself without removing the thermostat. You will need infrared thermometer (or regular kitchen one) and 10–15 minutes of time. Verification algorithm:

  1. Start the engine cold and watch the temperature gauge on the instrument panel.
  2. After 2–3 minutes, touch upper radiator hose (it comes from the thermostat). It should be cold - this means that the valve is closed and antifreeze circulates in a small circle.
  3. When the temperature needle reaches 80–85°C, the pipe should start to heat up. If it remains cold, the thermostat does not open.
  4. If the pipe gets warm immediately after starting the engine, the thermostat is stuck in the open position.

For more accurate diagnosis, you can use ELM327-scanner and program Torque Proto monitor the coolant temperature in real time. Normal graph: smooth increase to 82–88°C, then stabilization. If the temperature fluctuates or does not reach the operating range, the thermostat is faulty.

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On Almera G15 with air conditioning and climate control on, the thermostat may open earlier - this is normal. Check without loading the cooling system.

Original and similar thermostats for Almera G15: articles and prices

On Nissan Almera G15 Two types of thermostats were installed:

  • 🔧 Standard (for models 2012–2015) - article number 21200-4M50A (opens at 82°C).
  • 🔧 With temperature sensor (for models 2016–2019) - article number 21200-4M51A (opens at 88°C).

Original spare parts cost from 2,500 to 4,000 rubles, but there are high-quality analogues:

Brand Article Opening temperature Price, ₽ Note
Nissan 21200-4M50A 82°C 3 800–4 200 Original, suitable for all versions
Gates TH12318 82°C 1 200–1 500 High-quality analogue, time-tested
Vernet TH6557.82 82°C 900–1 100 Budget option, but lower resource
Mahle TH 30 82 82°C 1 800–2 200 Premium quality, recommended for turbocharged engines
Nipparts NTH-6012 88°C 1 400–1 700 For 2016+ models with temperature sensor

When choosing an analogue, pay attention to opening temperature - it must match the original. Thermostats at 88°C (e.g. Nipparts NTH-6012) are only suitable for Almera G15 2016–2019. Installing a thermostat with an incorrect opening temperature will lead to engine malfunctions.

⚠️ Attention: There are counterfeit brands on the market Gates And Mahle. Original thermostats from these manufacturers have a laser engraved logo and a holographic sticker on the packaging.

Step-by-step instructions for replacing the thermostat on Almera G15

Replacing the thermostat with Nissan Almera G15 does not require special tools, but will be required drain antifreeze (or at least part of it). Work is performed on a cold engine! You will need:

  • 🔧 Set of sockets and keys (10, 12, 14).
  • 🔧 Screwdriver with a flat tip.
  • 🔧 New thermostat with o-ring.
  • 🔧 Antifreeze (1–1.5 l for topping up).
  • 🔧 Container for draining coolant.

Drain the antifreeze (through the tap on the radiator or pipe)|Disconnect the negative terminal of the battery|Remove the air filter for access|Prepare a new thermostat and seal|Check the condition of the pipes for cracks-->

Next follow the instructions:

  1. Drain the antifreeze. Place a container under the radiator and open the drain valve (lower left corner of the radiator). An alternative is to remove the lower radiator hose.
  2. Remove the air filter. It interferes with access to the thermostat. Unscrew the 4 bolts securing the filter housing and move it to the side.
  3. Disconnect the pipes. Loosen the clamps on the two pipes going to the thermostat (upper and lower) and remove them. Be prepared for antifreeze residue!
  4. Remove the thermostat. Unscrew the 2 bolts securing the thermostat cover (head 12) and remove it. Remove the old thermostat and clean the seat of any remaining sealant or dirt.
  5. Install a new thermostat. Check that the O-ring is in place and install the part into the housing. Tighten the bolts crosswise with a force of 10–12 Nm.
  6. Connect the pipes and fill with antifreeze. Make sure the clamps are tight and add coolant to the correct level. Start the engine, warm it up and check for leaks.

After replacement be sure to remove any air pockets from the cooling system. To do this:

  1. Start the engine and let it run for 2-3 minutes with the expansion tank cap open.
  2. Press firmly on the lower radiator hose several times to expel the air.
  3. Add antifreeze to the level MAX and close the lid.
What happens if you don't remove air from the system?

Air locks lead to local overheating of the engine, even if the thermostat is working properly. The stove may also not work properly (blow cold air) or catch fire Check Engine due to false temperature sensor readings.

Common mistakes when replacing a thermostat and how to avoid them

Even experienced car owners make mistakes when replacing a thermostat with Almera G15. Here are the most common ones and how to prevent them:

  • 🔧 Using an old O-ring. Over time, the rubber loses elasticity and the new thermostat will leak. Always install new ring (comes with thermostat).
  • 🔧 Retightening of fastening bolts. This leads to deformation of the thermostat housing or breakage of the threads. Tighten the bolts to no more than 12 Nm.
  • 🔧 Wrong choice of antifreeze. On Almera G15 used CoolStream A-110 (green) or Nissan L255N (blue). You cannot mix them - this will cause the formation of sediment.
  • 🔧 Ignoring air pockets. If you do not bleed the air, the engine will overheat and the stove will work intermittently.

Another common mistake is purchasing a thermostat with the wrong opening temperature. For example, setting the thermostat to 88°C instead of 82°C will cause the engine to run at a higher temperature, which will accelerate oil wear and increase the risk of detonation. Always check the original part number!

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On Almera G15 with engine HR16DE after replacing the thermostat, it may be necessary to reset the throttle adaptations (via a scanner or by disconnecting the battery for 10 minutes).

How much does it cost to replace a thermostat at a service center?

The cost of replacing a thermostat Nissan Almera G15 in service depends on the region and level of the service station:

Service type Cost of work, ₽ Spare part cost, ₽ Total, ₽
Official dealer 2 500–3 500 3,800–4,200 (original) 6 300–7 700
Unofficial service 1 200–2 000 1,200–2,200 (analog) 2 400–4 200
Self-replacement 0 900–2 200 900–2 200

At official dealerships Nissan for replacing a thermostat they charge from 2,500 rubles, plus an original spare part will cost another 3,800–4,200 rubles. In independent services, the work is cheaper (1,200–2,000 rubles), but there is a risk of running into unscrupulous craftsmen who will install a low-quality analogue. Self-replacement allows you to save up to 50–70% of the cost.

If you decide to contact the service, please specify:

  • 🔧 Will they use new antifreeze or top up the old one.
  • 🔧 Do they provide a guarantee for the work (minimum 6 months).
  • 🔧 Will the system be checked for the presence air jams after replacement.

Frequently asked questions about the Almera G15 thermostat

Is it possible to drive with a faulty thermostat?

Short term - yes, but with caution. If the thermostat is stuck in open position, the engine will take longer to warm up, but the risk of overheating is minimal. If the thermostat is stuck in closed position - you cannot drive: there is a high risk of overheating and engine damage. In both cases, it is recommended to replace the part as soon as possible.

What antifreeze should I fill in after replacing the thermostat?

For Almera G15 class antifreezes are suitable G12+ or G12++ (carboxylate). Original fluids: Nissan L255N (blue) or CoolStream A-110 (green). You can't mix them! If you don’t know what kind of antifreeze was filled in previously, it is better to flush the system and fill in a new one.

Why does the engine take longer to warm up after replacing the thermostat?

Possible reasons:

  • A thermostat with a higher opening temperature is installed (for example, 88°C instead of 82°C).
  • There is still air in the system - you need to bleed the plugs.
  • Defective temperature sensor (on 2016+ models it is built into the thermostat).
  • Antifreeze with inappropriate additives is used (for example, silicate instead of carboxylate).
Can the thermostat be repaired or is it just a replacement?

The thermostat is a non-repairable part. Its valve operates using a heat-sensitive element (wax), which degrades over time. Attempts to “repair” the thermostat (for example, warm it up or flush it) will give a temporary effect, but will not solve the problem. The only reliable option is replacement with a new one.

How often do you need to change the thermostat on Almera G15?

The manufacturer does not establish strict replacement regulations, but it is recommended to check the operation of the thermostat every 60–80 thousand km. The average service life of an original part is 100–150 thousand km, but in practice it fails earlier due to:

  • Using low-quality antifreeze.
  • Engine overheating.
  • Corrosion in the cooling system.

If you notice signs of a malfunction (long warm-up, overheating), replace the thermostat without delay.