The engine cooling system is a complex mechanism, the coordinated operation of which determines the life of the vehicle’s power unit. On models Nissan Murano second generation (Z51), equipped with legendary engines VQ35DE, The thermostat is one of the critical parts. Over time, its sensitive element loses its tightness or jams, which leads to a violation of the temperature regime of the engine.
Ignoring signs of malfunction can lead to overheating and costly repairs of the cylinder head or complete engine failure. Crossover owners need to carefully monitor the temperature sensor readings and periodically check the condition of the cooling system components. Replacing the thermostat with Nissan Murano Z51 - the procedure is technically accessible, but requires accuracy and understanding of the process.
In this article we will look in detail at how to diagnose a malfunction, choose the right spare part and perform the replacement yourself. We will pay attention to the nuances of working with the VQ35DE engine, the features of draining antifreeze and tightening torques for connections so that you can avoid common mistakes.
Symptoms of a faulty thermostat and diagnosis
Determine if the thermostat is on your Nissan Murano requires replacement, based on a number of characteristic signs that appear during operation. The most obvious symptom is the behavior of the coolant temperature needle on the dashboard. If the engine takes a long time to warm up to operating temperature (about 90 degrees) even in frosty weather, this is a sure sign that the thermostat valve is stuck in the open position.
Otherwise, when the valve gets stuck closed, the engine overheats almost instantly after starting to move. In such a situation, the temperature needle touches the red zone, and the on-board computer issues a critical warning. Operating the car in this mode is strictly prohibited, since overheating leads to deformation of the cylinder head and burnout of the gaskets.
Also an indirect sign of a malfunction is uneven heating of the radiator pipes. If the thermostat is working properly, the upper radiator hose should remain cold until the engine warms up, after which it will suddenly heat up. If it heats up immediately after starting the engine, it means that the circulation is constant in a large circle.
Another indicator is sudden changes in temperature when driving along the highway. The arrow can either fall to a minimum or quickly rise up. This indicates that the thermostat valve is unstable, periodically opening and closing chaotically, disrupting heat exchange.
- ⚠️ Long-term warming up of the engine to operating temperature 90°C in winter.
- ⚠️ The temperature arrow quickly goes into the red zone and the alarm goes off.
- ⚠️ Uneven heating of the lower and upper radiator pipes.
- ⚠️ Increased fuel consumption due to engine operation in warm-up mode.
Selection of original spare parts and analogues
When choosing a new part to replace with Nissan Murano Z51 It is important to understand that the quality of the thermostat directly affects the stability of the entire cooling system. Original spare part from Nissan has a catalog number 21010-ED000 (for VQ35DE engines). It ensures precise opening of the valve at temperature 82°C and is highly reliable, but is quite expensive.
There are high-quality alternatives on the market, which are often offered by dealers themselves as original, since they are produced at the same partner factories. Among the reliable analogues are brands Petral, Denso and Calsonic. These manufacturers guarantee compliance with all technical specifications and materials used in the production of the housing and sensing element.
You should avoid cheap non-original thermostats from little-known brands, especially those made in China. Their body can be made of low-quality plastic, which cracks at the first thermal shock, and the temperature threshold can be greatly underestimated or overestimated.
Be sure to check the packaging for the presence of holograms and compliance with the article numbers. When purchasing an original part, make sure that a new thermostat gasket is included, as reusing an old gasket is unacceptable and can lead to coolant leaks.
- ✅ Original thermostat Nissan (art. 21010-ED000) - maximum reliability and accuracy.
- ✅ Brand Denso - an excellent analogue, often supplied in original Nissan packaging.
- ✅ Brand Calsonic is a time-tested manufacturer of cooling components.
- ❌ Cheap analogues without markings are a risk of leaks and incorrect operation.
Required tools and materials
Before starting work on replacing the thermostat, Nissan Murano It is necessary to prepare all the tools and consumables so that the process is not interrupted at the most inopportune moment. To access the unit, you will need to dismantle some elements of the engine compartment, so a set of sockets and screwdrivers is required.
You will need a standard set of wrenches and sockets, including 10mm, 12mm and 14mm sizes. You will also need a Phillips screwdriver and possibly an extension cord for working in hard-to-reach places. Do not forget to prepare a container for draining antifreeze, since the volume of coolant in the system is about 8-9 liters.
The key is to have a new thermostat, a new gasket (if it doesn't come with one), and fresh antifreeze. For VQ35DE engines it is recommended to use original antifreeze Nissan Long Life Coolant (green or pink, depending on the year of manufacture and specification), which has the necessary anti-corrosion properties.
- 🔧 Set of sockets with a collar and an extension (sizes 10, 12, 14 mm).
- 🔧 Phillips screwdriver and flat screwdriver for removing clamps.
- 🔧 Container for draining used coolant (volume of at least 10 liters).
- 🔧 New thermostat and gasket, as well as a supply of antifreeze.
- Engine overheating
- Long warm-up
- Scheduled maintenance
- Sensor malfunction
Step-by-step replacement instructions
The replacement process begins with preparing the car. Make sure the engine is completely cool, otherwise opening the cooling system will cause burns from hot steam and liquid. Open the hood, lock it and locate the cooling system expansion tank. Drain a small amount of antifreeze from the reservoir so that the fluid level in the system drops below the thermostat installation location.
Next, you will need to remove the air filter and air filter housing to gain access to the top of the engine and thermostatic assembly. Disconnect the sensor connectors and crankcase ventilation hoses if they interfere with dismantling. Use 10 mm wrench for unscrewing the clamps of the pipes supplying and discharging liquid to the thermostat.
After removing the pipes, you can unscrew the bolts securing the thermostat housing to the cylinder block. Usually there are two or three. Carefully remove the housing, being careful not to damage the adjacent surface of the unit. Remove the old thermostat and clean the seat of any remaining gasket and sealant. This is critical to ensuring the sealing of the new assembly.
Install the new gasket and the thermostat itself into the housing, making sure that it is positioned correctly (the valve should face down or to the side corresponding to the direction of flow). Screw the housing to the cylinder block, observing the tightening torque. Excessive force may cause the aluminum housing to crack or the gasket to deform.
☑️ Preparing to replace the thermostat
Filling the system and removing air pockets
After installing a new thermostat, the cooling system must be properly primed. This is one of the most critical stages, since the presence of air pockets can lead to local overheating of the engine, even if the thermostat is working properly. Open the radiator cap (if equipped) or expansion tank.
Slowly pour new antifreeze into the expansion tank, observing the level. Do not top up all at once. Start the engine and let it idle. Turn on the heater in the cabin to maximum temperature and maximum fan speed to open the heater valve and force fluid through the heater radiator.
As the engine warms up, the fluid level in the reservoir will drop and air bubbles will leave the system. Add antifreeze to the required level until bubbles stop coming out of the system and the radiator fan turns on at full power. This is a sign that the thermostat has opened and fluid has begun to circulate in a large circle.
To better remove air pockets on a Nissan Murano, you can slightly raise the front of the car so that the expansion tank is at the highest point in the system.
Torque table and specifications
Compliance with the correct tightening torques of fasteners guarantees the absence of leaks and damage to components. For VQ35DE engine on Nissan Murano Z51 There are strict manufacturer recommendations for tightening the thermostat mounting bolts and pipes. Neglecting this data can lead to serious problems.
The following table shows the main parameters that must be observed when assembling the unit. Please note that values may vary slightly depending on the specific engine version, so always check the factory documentation if available.
| element | Bolt size | Tightening torque (Nm) | Note |
|---|---|---|---|
| Thermostat housing mounting bolts | 10 mm | 10-12 | Tighten crosswise |
| Pipe clamps (spring) | — | — | Press until it clicks |
| Pipe clamps (screw) | — | 2-3 | Do not overtighten so as not to push through the rubber. |
| Radiator drain plug | 12 mm | 5-7 | Be careful, aluminum is soft |
If you use screw clamps, make sure they are tightened evenly around the entire circumference, but not too tight as to deform the rubber tube. For spring clamps, use special pliers to securely lock them in position.
Common mistakes when replacing
1. Reusing an old gasket, which leads to leaks. 2. Insufficient cleaning of the seat from dirt and sealant. 3. Ignoring the removal of air pockets, leading to overheating. 4. Using an incompatible type of antifreeze that causes sedimentation.
Warnings and Important Notes
Working with the cooling system requires compliance with safety precautions and attention to detail. One of the main dangers is working with a hot engine. Never open the expansion tank or radiator cap on a hot engine, as system pressure may release boiling antifreeze, causing severe burns.
It is also important to prevent dirt and debris from entering the system during replacement. Even a small grain of sand can cause clogging of the thin channels of the radiator or pump. Use only clean tools and new gaskets. If you use sealant, apply it very thinly so that excess does not get into the system.
After completing the work, be sure to check the system for leaks within several days of operation. Inspect the connections of the pipes and the thermostat housing. If you notice signs of leakage, stop the engine immediately and eliminate the cause.
⚠️ Attention: If the engine continues to overheat after replacing the thermostat, the problem may not be solely with the thermostat. Check the operation of the radiator fan, the condition of the pump and the absence of air pockets in the system.
⚠️ Attention: Use only antifreeze recommended by the manufacturer. Mixing different types (for example, green and red) can create a chemical residue that will clog the radiator and ruin the pump.
Correctly replacing the thermostat and removing air pockets is the key to stable operation of the VQ35DE engine in the Nissan Murano Z51 under any operating conditions.
Frequently asked questions and answers (FAQ)
In this section we will answer the most popular questions that owners have Nissan Murano when replacing the thermostat. These answers will help you avoid unnecessary costs and mistakes when doing your own repairs.
How long does it take to replace the thermostat on a Nissan Murano Z51?
For an experienced technician, the replacement takes from 1 to 2 hours. If you are doing this for the first time and do not have special tools, allow 3-4 hours, including time for cooling the engine, draining and filling antifreeze.
Can I use sealant instead of gasket?
It is not recommended to use sealant instead of a gasket on the VQ35DE thermostat. The factory gasket is made of special materials that can withstand high temperatures and pressure. The sealant can dissolve in the antifreeze or create excess that will clog the system.
What is the best antifreeze for Murano Z51?
The optimal choice is original antifreeze Nissan Long Life Coolant. Quality organic acid based (OAT) analogues such as G12+ or G13, but they must be carefully selected for color compatibility and specification.
Do I need to change the thermostat if it's just stuck open?
Yes, replacement is required. An engine operating at too low a temperature does not reach optimal operating conditions, which leads to increased fuel consumption, rapid wear of the cylinder-piston group and deterioration of environmental performance.
How to check the functionality of the old thermostat?
You can remove the thermostat and lower it into a container of water, heating it on the stove. Measure the water temperature with a thermometer. The thermostat should start opening at around 82°C and fully open by 95°C. If it does not open or opens too early/late, it is faulty.