Parts for your 2017 Nissan Serena-Radiator cap

2017 Nissan Serena radiator cap

Nissan’s technical literature for the C27-series Serena (Cooling System section of the Service Manual, the 2017 Owner’s Manual coolant-filling guidance, and the Nissan FAST parts catalogue listing CAP-RADIATOR for C27) shows the vehicle uses a sealed radiator with a pressurised expansion tank. That means there’s no separate cap on the radiator neck. Instead, the pressure cap lives on the coolant reservoir and performs the same job a traditional radiator cap would. So yes, a radiator cap is used on the 2017 Nissan Serena — it’s just fitted to the reservoir rather than the radiator itself.

On the Serena, the “radiator cap” on the reservoir is a small but crucial bit of kit. It seals and pressurises the cooling system (typically around 1.1 bar / 108 kPa, per Nissan spec), which bumps up the coolant’s boiling point and helps keep temperatures steady under load. Inside the cap are two valves: one that holds pressure when the engine’s hot, and a vacuum valve that lets coolant draw back from the overflow as things cool down. That two-way action keeps air out, helps de-gas the system, and stops hoses from collapsing.

As part of routine servicing, it’s smart to check the cap every time the bonnet’s up. Look for a cracked or flattened rubber seal, a weak or sticky spring, corrosion on the seat, or crusty/gel-like residue. Any of those is a cue to replace it. If a tester’s handy, have the cap pressure-checked to its rated kPa. Always let the Serena cool fully before opening the cap — hot coolant under pressure can erupt. A thick rag and a slow, quarter-turn to bleed pressure first is the go.

When replacing, match the pressure rating and neck style, and go for a genuine or OE-equivalent cap. After fitting, top the reservoir to the mark with Nissan Genuine Blue long-life coolant (premix) and bleed any trapped air per the service procedure. A short road test with the heater on helps confirm proper circulation. Most owners will be fine inspecting at each service and replacing the cap about every 4–5 years or 80–100,000 km, sooner if there are symptoms like gradual coolant loss, overheating in traffic, a sweet coolant smell, or hoses that look sucked-in after cooldown.

• Never open the cap hot, wear eye protection.
• Keep the reservoir neck clean so the new seal seats properly.
• If the cap keeps venting, check for a weak cap, blocked return hose, or underlying cooling-system faults.

Popular questions about 2017 Nissan Serena radiator caps

Does the 2017 Serena actually have a radiator cap?
Yes. It doesn’t sit on the radiator neck, it’s on the pressurised coolant reservoir. This cap manages system pressure and coolant flow to and from the overflow, exactly like a traditional radiator cap does.

What pressure cap should be used?
Nissan specifies roughly 1.1 bar (about 108 kPa) for the C27 Serena. Using the correct pressure rating maintains the designed boiling point and protects hoses, seals, and the heater core.

How often should the cap be replaced?
Check it at every service and replace it about every 4–5 years or 80–100,000 km, or sooner if the seal’s perished, the spring’s weak, or there are cooling issues like gradual coolant loss or overheating in stop–start driving.