<em>Nissan Note</em> cooling system: how it works, typical breakdowns and do-it-yourself repairs

Cooling system design Nissan Note: scheme and principles of operation

Cooling system Nissan Note (first and second generations, E11 And E12) is a closed circuit with forced circulation of antifreeze that maintains the optimal engine temperature HR16DE (1.6 l) or HR12DE (1.2 l). Unlike many budget cars, it uses double-circuit circuit: small circle (for quick heating) and large circle (for intensive cooling). Main elements of the system:

Central node - pump (water pump)which is driven by the timing belt. This means that if the belt breaks, the engine will not only stall, but also the risk of overheating increases by 3–4 times due to stopping the circulation of antifreeze. The thermostat, located in the housing next to the pump, opens at temperature 82–88°C (depending on version), directing the liquid to the radiator. Important: in Note used plastic expansion tank, which can crack over time - this is one of the common causes of antifreeze leaks.

• 🔧 Pump — driven by a timing belt, resource ~100–120 thousand km (at HR16DE often fails earlier).
• 🌡️ Thermostat - opens when 82–88°C, when stuck in the closed position, the engine overheats.
• 🚗 Radiator — aluminum, with plastic tanks; vulnerable to corrosion when using low-quality antifreeze.
• ⚡ Cooling fan - turns on based on a signal from the temperature sensor (on Note E12 relay contacts often burn out).

Feature Nissan Note — compact layout of the engine compartment, which complicates access to some elements. For example, to replace a thermostat with HR16DE it is necessary to remove the intake manifold, and the antifreeze is drained through two taps: one on the radiator, the second on the engine block (they often forget to open the second one, which is why the liquid does not drain completely).

Typical malfunctions: signs and causes

Engine overheating Nissan Note - the most dangerous malfunction that can lead to cylinder head deformation or jamming of the piston group. The first symptoms of problems with the cooling system:

• 🔥The temperature arrow on the dashboard rises higher 90°C (at idle or in a traffic jam).
• 💦 Antifreeze leaks under the car (bright green, red or blue liquid).
• 🌀 An emulsion (a mixture of antifreeze and oil) is visible in the expansion tank - a sign of a broken cylinder head gasket.
• 🔊 Extraneous noises from under the hood (creaking or humming) - the pump bearing may be worn out.

The most common causes of malfunctions:

Malfunction	Reason	Consequences
Antifreeze leak	Cracks in the expansion tank or pipes, pump wear	Overheating, risk of air locks
Thermostat stuck	Corrosion or scale (when using water instead of antifreeze)	Constant operation in a small circle → overheating
Fan doesn't work	Failure of the temperature sensor or relay	Overheating in traffic or idling
Pump wear	Natural wear (resource ~100 thousand km) or quality of antifreeze	Broken timing belt, engine damage

Particular attention should be paid expansion tank. On Nissan Note E11 (2006–2012) it often cracks at the seam, and on E12 (2012-2020) - leaks through the cap valve. Sign of a problem: the tank swells, and when you open the lid you hear a hissing sound (excessive pressure). If you ignore this malfunction, antifreeze can be squeezed out through weak pipe connections, which will lead to an air lock and local overheating.

⚠️ Attention: On Nissan Note with engine HR16DE When replacing the pump, be sure to check the condition of the timing belt. If there are cracks or delaminations on it, replace it as a set (belt + rollers). Otherwise, the risk of a break increases 5 times!

Cooling system diagnostics: step-by-step instructions

Checking the cooling system Nissan Note You can do it yourself without resorting to a diagnostic scanner. Start with a visual inspection:

1. Check the antifreeze level in the expansion tank. It should be between the marks MIN And MAX on a cold engine. If the level drops regularly, look for a leak.
2. Inspect the pipes for cracks or wet spots. The pipes leading to the radiator and heater are especially vulnerable.
3. Check the thermostat operation:
   • Start the engine and touch the upper radiator hose. It should be cold for the first 5-7 minutes, then warm up quickly (this means the thermostat has opened).
   • If the pipe heats up immediately, the thermostat is stuck in the open position; if it remains cold, keep it closed.
4. Cooling fan test:
   • When the temperature is reached 95–100°C (on the dashboard) the fan should turn on. If this does not happen, check the fuse F30 (10A) and relay K26 in the mounting block.

For in-depth diagnostics you will need:

• 🔧 Pressure check in the system (at service stations they use a pump with a pressure gauge). Normal pressure - 1.1–1.3 bar. If it falls, there is a leak.
• 🔍 Checking antifreeze for oil (a sign of a broken cylinder head gasket). It is enough to drop liquid onto the paper: if greasy stains remain, the problem is serious.
• 📊 Reading errors (if lit CHECK ENGINE). Frequent codes: P0128 (low coolant temperature), P0217 (engine overheating).

Check the antifreeze level|Inspect the pipes for leaks|Check the operation of the thermostat (heating of the pipes)|Make sure the fan turns on at 95°C|View errors with a scanner (if any)-->

⚠️ Attention: On Nissan Note E12 with engine HR12DE The coolant temperature sensor is located not on the thermostat, but on the cylinder head. When replacing it, you need to drain the antifreeze completely, otherwise an air lock is guaranteed!

Replacing the pump with Nissan Note: step by step instructions with photos

Pump on Nissan Note with engines HR16DE/HR12DE changes together with the timing belt (recommended interval - 100–120 thousand km). If the pump begins to leak or make noise earlier, it is replaced separately, but this requires removing the timing belt. To work you will need:

• 🔧 Set of sockets and keys (including the socket on 10 mm for pump bolts).
• 🛠️ New pump (original - 21010-EA20A for HR16DE).
• 🧰 Sealant (for example, Loctite 574 for laying).
• 🚰 Antifreeze (5 l, specification Nissan L250 or similar G12+).

Step by step instructions:

1. Drain the antifreeze:
   • Open the valve on the radiator (bottom right) and the valve on the engine block (protected by the plastic plug).
   • Remove the pipe from the throttle assembly to speed up draining.
2. Remove the timing belt:
   • Fix the crankshaft and camshafts according to the marks (use a special wrench or a screwdriver through the hole in the flywheel).
   • Loosen the tension roller and remove the belt.
3. Remove the pump:
   • Unscrew the 6 bolts securing the pump (head on 10 mm).
   • Remove the pump, clean the seat from the old sealant.
4. Install a new pump:
   • Apply a thin layer of sealant to the new pump gasket.
   • Tighten the bolts crosswise to torque. 20–25 Nm.

Reassemble everything in reverse order, fill in antifreeze and remove air pockets (see next section).

How to check the pump without removing it?

If it is not possible to remove the pump, you can check it like this:

1. Start the engine and allow it to warm up to operating temperature.

2. Pinch the upper radiator hose with your hand (be careful, it is hot!). If you feel the antifreeze pulsating, the pump is working. If the pipe is soft and there is no pulsation, the pump is faulty.

3. Listen to the pump for any extraneous noise (a creaking or humming noise indicates bearing wear).

Important: when replacing the pump with Nissan Note necessarily check the condition of the crankshaft oil seal. If it leaks, the antifreeze will mix with the oil, causing engine failure. A sign of a problem is emulsion on the oil filler cap.

How to remove an air lock: 3 proven methods

Air lock in the cooling system Nissan Note - a common problem after replacing antifreeze or repairs. It leads to uneven heating of the engine, poor operation of the stove and false fan activations. Removal methods:

Method 1: Through the expansion tank

1. Start the engine and let it warm up until 80–90°C (the temperature arrow should be in the middle of the scale).
2. Unscrew the cap of the expansion tank (be careful, it may be hot!).
3. Add antifreeze to the maximum and squeeze the upper radiator hose with your hand several times to squeeze out the air.
4. Close the lid and check the operation of the stove (hot air should be blowing).

Method 2: Through the throttle body pipe

This method is more effective, but requires caution:

1. Remove the pipe coming from the throttle body to the cooling system (it is usually thinner than the others).
2. Start the engine and let it run for 2-3 minutes. Antifreeze will begin to flow out of the pipe - at this moment, quickly put it back on and secure it with a clamp.
3. Add antifreeze to the tank to the level.

Method 3: Using Slope

Suitable if the first two methods did not help:

1. Drive the car onto an overpass or slope so that the front is higher than the rear.
2. Start the engine, open the expansion tank cap and let it idle for 5-10 minutes.
3. Periodically accelerate until 2500–3000 rpmto speed up circulation.

After removing the plug, be sure to check:

• 🔥 The temperature of both radiator pipes (should be equally hot).
• 💨 The operation of the stove (the air should be hot in all modes).
• 📉 Antifreeze level (add if necessary).

⚠️ Attention: On Nissan Note E12 with air conditioning, when the air lock is removed, the fan may operate even on a cold engine. This is normal - the system checks the pressure in the circuit.

Choosing antifreeze for Nissan Note: what to fill and how much

To the cooling system Nissan Note (both generations) filled with antifreeze specifications Nissan L250 (blue or green). This carboxylate antifreeze ethylene glycol based, compatible with aluminum radiators. System volume:

Engine	Antifreeze volume (l)	Recommended original	Analogues
HR16DE (1.6 l)	5.5–6.0	Nissan Coolant L250 (KE902-99932)	Coolstream Premium, Sintec Unlimited G12++
HR12DE (1.2 l)	4.5–5.0	Nissan Coolant L250	Ravenol HJC Hybrid, Motul Inugel Optimal

Important: do not mix different types of antifreeze (For example, G11 And G12+). This will cause sediment to form, which will clog the radiator and thermostat. If you do not know what antifreeze was filled in previously, perform complete flushing of the system:

1. Drain the old antifreeze.
2. Fill with distilled water and let the engine run for 10-15 minutes.
3. Drain the water and repeat the procedure 2-3 times until the water runs clear.
4. Refill with new antifreeze.

On Nissan Note with mileage over 100 thousand km It is recommended to use antifreeze with additives against aluminum corrosion (for example, Coolstream A-110). This is due to wear on the internal surfaces of the radiator and pump.

Frequently asked questions about the cooling system Nissan Note

🔧 Why does the temperature rise to 100°C at idle, but drops when driving?

This is a typical sign faulty cooling fan or temperature sensor. At idle, there is no oncoming air flowing through the radiator, and if the fan does not turn on, the temperature rises. When moving, the air flow cools the radiator and the temperature returns to normal. Check:

• fuse F30 (10A) in the mounting block.
• Fan relay K26 (located next to the fuses).
• Condition of the temperature sensor connector (contacts often oxidize).

💦 Is it possible to temporarily add water instead of antifreeze?

In an emergency (for example, on the road), top up distilled water possible, but no more 0.5–1 l. After this, as soon as possible:

1. Drain the water and antifreeze mixture.
2. Flush the system with distilled water.
3. Refill with fresh antifreeze Nissan L250.

Using plain water or driving for a long time with diluted antifreeze will lead to corrosion of aluminum parts and the formation of scale in the radiator.

🚗 How often should you change antifreeze in Nissan Note?

Official regulations Nissan provides for replacing antifreeze every 90 thousand km or 5 years (whichever comes first). However, for Russian conditions (sudden temperature changes, poor-quality roads), it is recommended to reduce the interval to 60–70 thousand km or 3–4 years. Signs that it’s time to change the antifreeze:

• Change in color (darkening, cloudiness).
• The appearance of sediment in the expansion tank.
• Frequent overheating for no apparent reason.

🔥 What to do if the engine is already overheated?

If the temperature arrow goes into the red zone (110°C and above), immediately:

1. Stop turn off the engine and open the hood.
2. Do not open the expansion tank cap immediately - risk of burns! Wait 15–20 minutes.
3. Check the antifreeze level. If it is not there, add water (as a last resort).
4. If there is antifreeze, but the engine is heating up, do not start it. Call a tow truck or look for the cause (for example, a broken pump belt).

After overheating, be sure to check:

• Condition of the cylinder head gasket (a sign of burnout is white smoke from the exhaust pipe).
• Compression in the cylinders (must be at least 12 bar in each).

🛠️ Is it possible to replace the cooling radiator yourself?

Replacing the radiator with Nissan Note - a task of medium complexity. You will need:

1. Drain the antifreeze (through the tap on the radiator and engine block).
2. Remove the front bumper (on E12) or radiator grille (on E11).
3. Disconnect the pipes and electrical connector of the fan.
4. Unscrew the radiator mountings (4 bolts) and remove it.

Difficulties:

• On Note E12 The radiator is attached together with the air conditioner condenser - you will have to carefully move it to the side.
• When installing a new radiator, check the condition of the rubber cushions (they often tear).

The cost of the original radiator is ~12–15 thousand rubles. Analogs (for example, Denso or Nissens) will cost 8–10 thousand rubles.