<em>Nissan Murano Z51</em>radiator neck: device, faults and do-it-yourself replacement

Nissan Murano Z51 is a popular crossover known for its reliability and comfort. However, even such proven models have vulnerabilities, one of which is radiator neck. This seemingly insignificant detail can become a source of serious problems: from antifreeze leakage to engine overheating. In this article we will look at why the neck breaks, how to diagnose it, what spare parts to choose and how to replace it yourself - taking into account the nuances of a particular generation Z51 (2015–2022).

Feature Murano Z51 — an aluminum radiator with a plastic neck, which loses its elasticity over time due to temperature changes and the aggressive effects of coolant. If you ignore cracks or chips on this unit, the risk of air getting into the cooling system increases significantly, which leads to formation of air jams and deterioration of heat transfer. We have collected all the relevant information, including original part numbers for different markets (Japan, USA, Europe), as well as proven analogues from Denso, Nissens and other brands.

The design and function of the radiator neck in Nissan Murano Z51

The radiator neck is not just a cap, but a key element of the cooling system that performs several tasks:

• 🔧 Sealing the system: Prevents antifreeze leakage and air ingress by maintaining the required pressure (at Murano Z51 standard system pressure - 1.1–1.3 bar).
• 🌡️ Pressure adjustment: a built-in valve relieves excess pressure when the liquid heats up, protecting the radiator and pipes from rupture.
• ⚠️ Level control: add antifreeze through the neck and visually inspect the condition of the coolant.

On Murano Z51 The neck is integrated into the top of the radiator and is made of heat-resistant plastic (usually polypropylene or polyamide). However, over time, the material degrades: microcracks appear, the seal of the valve is disrupted, and the thread wears out from frequent unscrewing. Particularly vulnerable are cars operated in regions with sharp temperature changes (for example, in Russia or Canada), where the plastic is subject to additional stress.

It is important to understand that the neck is connected to expansion tank through the overflow hose. If the neck valve becomes stuck in the closed position, the pressure in the system may exceed a critical value, which will lead to rupture of pipes or the radiator itself. In practice, this often manifests itself as a sudden leak of antifreeze for no apparent reason.

Signs of a bad radiator neck

Throat problems rarely appear suddenly; they are usually preceded by indirect symptoms. If you notice at least one of the following signs, it is worth inspecting the part:

• 💦 Traces of antifreeze under the hood near the radiator or on the engine protection (the fluid may be green, red or blue, depending on the type of coolant).
• 🔥 Engine overheating for no apparent reason (the temperature arrow on the dashboard rises above normal, the cooling fan turns on more often than usual).
• 🌀 Air jams: The heater blows cold air even though the engine is warm, or gurgling sounds are heard from the system.
• 🔩 Difficulty unscrewing the lid: the thread is “stuck” or, conversely, the lid rotates without fixing.

One of the most insidious symptoms is gradual decrease in antifreeze level without visible leaks. In this case, the liquid may evaporate through microcracks in the neck or a leaky valve. This is easy to check: after stopping the engine completely (after 1-2 hours), inspect the neck for moisture or dried antifreeze crystals around the threads.

⚠️ Attention! Never open the radiator cap on a hot engine - this may result in the release of steam and burns. Wait until the coolant temperature drops below 50°C (you can focus on turning off the cooling fan).

Another test: start the engine and let it warm up to operating temperature. Carefully (wearing gloves!) touch the hose connecting the neck to the expansion tank. If he bloated or hard to the touch, this is a sign that the filler valve is not releasing pressure. In this case, the part must be replaced.

Causes of radiator neck failures Murano Z51

The main factors that shorten the life of the neck:

Reason	Consequences	How to prevent
Natural wear and tear of plastic	Cracks, loss of tightness	Replace every 80–100 thousand km or 5–6 years
Using low-quality antifreeze	Corrosion of metal elements, corrosion of plastic	Use only Nissan Long Life Coolant or analogues (CoolStream A-110, Sintec Unlimited G12++)
Overtightening the cap	Thread failure, o-ring deformation	Screw the lid with no more force than 2–3 Nm
Oil getting into the cooling system	Destruction of seals, jamming of valve	Regularly check the condition of the oil and antifreeze for mixing

Feature Murano Z51 - sensitivity to coolant composition. For example, the use of cheap antifreeze based ethylene glycol without an additive package, it accelerates the degradation of neck plastic by 2–3 times. Original Nissan Coolant contains special corrosion inhibitors that protect not only metal parts, but also plastic elements of the system.

Another common problem is valve jamming due to sediment accumulation. This happens if you do not change the antifreeze for a long time (the recommended interval for Murano Z51 - every 90 thousand km or 5 years). In this case, the valve stops releasing pressure, which leads to:

• 💥 Burst of pipes (especially the upper one going to the thermostat).
• 🔧 Radiator deformation (aluminum honeycombs can “swell”).
• 🚨 Emergency engine shutdown due to overheating (at Murano Z51 protection is triggered when 110°C).

Selection of spare parts: original vs analogues

For Nissan Murano Z51 (2015–2022) the original radiator neck is supplied under the article number:

• 21460-4M00A - for models with engine VQ35DE (3.5 l).
• 21460-4M01A - for restyled versions (from 2019).

The cost of the original part is from 2,500 to 4,000 rub. depending on the region. However, there are high-quality analogues on the market that are cheaper:

Brand	Article	Price, rub.	Features
Denso	221-5001	1 800–2 200	Complete analogue of the original, supplier for Nissan to the conveyor
Nissens	85104	1 500–1 900	Reinforced O-ring, suitable for heavy-duty applications
Febi Bilstein	21460	1 200–1 600	Budget option, but less resource (about 50 thousand km)
Gates	31665	2 000–2 400	Comes with a new gasket and o-ring

When choosing an analogue, pay attention to:

• 🔍 O-ring material: optimal - silicone or fluoroelastomer (FPM).
• 📏 Thread accuracy: Some cheap analogues have misalignment, causing the lid to not fit tightly.
• 🛡️ Availability of certificate: trusted brands (Denso, Nissens) guarantee compliance with original specifications.

⚠️ Attention! There are counterfeits of original items on the market Nissan. They can be distinguished by the quality of the plastic (the original is matte, without burrs) and the presence of a holographic sticker on the packaging. Buy spare parts only from authorized dealers or trusted suppliers.

If you plan to replace the neck yourself, we recommend immediately purchasing:

• 🔧 New o-ring (article 21468-4M000).
• 🧴 Thread sealant (For example, Loctite 577).
• 🧤 Antifreeze for topping up (no less 1 l).

Step-by-step instructions for replacing the radiator neck

Replacing the neck with Nissan Murano Z51 does not require special skills, but will require accuracy and compliance with safety precautions. The whole process will take about 1.5–2 hours.

Wait until the engine cools down completely (at least 2 hours after the trip)|Prepare a container for draining the antifreeze (volume of at least 5 liters)|Disconnect the negative terminal from the battery|Prepare tools: 10mm wrench, screwdriver, pliers|Wear gloves and safety glasses-->

Step 1: Drain the antifreeze

To minimize coolant loss, perform a partial drain:

1. Place a container under the radiator drain hole (lower right corner).
2. Unscrew the drain plug (key on 10) and drain about 1–1.5 l antifreeze.
3. Screw the plug back to prevent air from entering the system.

Step 2. Dismantling the old neck

Carefully remove the hose connecting the neck to the expansion tank (loosen the clamp with pliers). Then:

1. Unscrew the neck counterclockwise. If the threads are stuck, use a penetrating lubricant (WD-40 or Liqui Moly Rostloser).
2. Clean the seat on the radiator from the remains of the old seal and dirt (use a lint-free rag and alcohol).

Step 3. Installing a new neck

Before installation, apply a thin layer of sealant to the threads of the new neck. Screw it in by hand until it stops, then tighten it with a wrench with a force of no more than 2–3 Nm. Connect the hose to the expansion tank and secure with a clamp.

Step 4: Charging the system and checking

Add antifreeze to the level MAX in the expansion tank. Start the engine and let it warm up to operating temperature (the fan should turn on 2-3 times). Check:

• 🔍 No leaks around the neck.
• 🌡️ Temperature stability on the dashboard.
• 🌀 No air jams (the stove should blow hot air).

Common replacement mistakes and how to avoid them

Even experienced car owners sometimes make mistakes that lead to repeated breakdowns. Here are the most common:

• 🔧 Neck drag: This will deform the O-ring and may cause cracks. Use a torque wrench!
• 🧹 Ignoring footprint cleaning: Dirt or old sealant residue will compromise the seal.
• 🚫 Using incompatible antifreeze: mixing different types of coolant causes the formation of sediment, which clogs the neck valve.
• ❄️ Replacement without warming up the engine: air pockets will not leave the system, which will lead to incorrect temperature sensor readings.

Another typical problem is incorrect antifreeze filling sequence. On Murano Z51 It is important to first pour liquid into the radiator (through the neck), and then add it to the expansion tank. If you do the opposite, air will remain in the system, which will interfere with circulation.

⚠️ Attention! If the engine continues to overheat after replacing the filler neck, check thermostat (article 21200-4M000) and temperature sensor (25060-4M000). On Murano Z51 these parts often fail at the same time as the neck.

Also do not forget that after replacing the neck it is necessary reset errors in the engine control unit (if any). To do this, you can use a diagnostic scanner (Launch X431, Autel MaxiCOM>) or contact the service. Error codes related to the cooling system on Murano Z51:

• P0128 — low coolant temperature.
• P0217 - engine overheating.
• P0597 - Thermostat malfunction.

Prevention and extension of neck service life

To make your radiator neck last longer, follow these recommendations:

• 🔄 Change antifreeze regularly: every 90 thousand km or 5 years (for Murano Z51 optimal Nissan Long Life Coolant).
• 🧴 Use additives: additives type Liqui Moly Kuhler-Dichter strengthen plastic and seals.
• 🌡️ Control your blood pressure: Once a year, check the operation of the neck valve (when heated, it should release excess pressure).
• 🛠️ Handle the cover with care: Do not use excessive force when tightening.

Pay special attention winter operation. At low temperatures, plastic becomes brittle, therefore:

• ❄️ Do not add cold coolant to a hot engine - this causes microcracks.
• 🚗 Try to park in a warm garage to minimize temperature changes.

If you frequently drive off-road or in dusty conditions, it is recommended that you 20 thousand km flush the cooling system with special compounds (for example, Hi-Gear Radiator Flush). This will prevent deposits from building up and blocking the filler valve.

What to do if the neck bursts on the road?

If the neck cracks during a trip and you don’t have a replacement at hand, temporarily cover the radiator hole with a thick rag and secure it with a clamp. Drive at low speed (no more than 60 km/h) and monitor the temperature. Replace the part as soon as possible - this “repair” is short-lived!

FAQ: Frequently asked questions about the radiator neck Nissan Murano Z51

Is it possible to drive with a cracked radiator neck?

Short term - yes, but with caution. A crack will lead to loss of antifreeze and air entering the system, which can lead to overheating. If the crack is small, you can temporarily seal it with epoxy resin (Loctite Epoxy), but this is not a long-term solution. Replace the neck as soon as possible.

What antifreeze should I fill in after replacing the neck?

For Murano Z51 suitable only carboxylate antifreeze class G12++ or G13. Original liquid - Nissan Long Life Coolant (blue color, article number KE902-99932). You can use analogues: CoolStream A-110, Sintec Unlimited G12++ or Motul Inugel Optimal. Do not mix different types of antifreeze!

Why does the stove blow cold air after replacing the neck?

This is a sign air lock in the cooling system. To fix it:

1. Stop the engine and let it cool.
2. Remove the hose from the throttle body (it comes from the cooling system).
3. Add antifreeze to the radiator up to the top of the filler neck.
4. Start the engine and let it run for 5-7 minutes - air will escape through the removed hose.
5. Reinstall the hose and add antifreeze to the level.

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

Cost of work at an official dealership Nissan - from 1,500 to 2,500 rub. In independent services the price is lower: 800–1,200 rub.. However, if you replace the part yourself, you will save not only on work, but also on diagnostics (many service stations charge 500–1,000 rub. for checking the cooling system).

Can I use the neck from other Nissan models?

Theoretically suitable necks from Nissan Pathfinder R52 (article 21460-4M000) and Infiniti QX60 (article 21460-4M01A), since these models have a similar cooling system. However, the shape of the O-ring and the length of the fitting for the expansion tank hose may differ. Before purchasing, compare visually or from the catalogue.