Parts for your 2010 Nissan Serena-Radiator cap

2010 Nissan Serena radiator cap — purpose, fitment and servicing tips

Based on technical references including the Nissan Serena C25/C26 Factory Service Manual (Cooling System – CO), the MR20DE engine uses a sealed, pressurised cooling system with a cap fitted to the reservoir/expansion tank rather than on the radiator neck. Nissan’s FAST electronic parts catalogue lists a “Cap Assy – Radiator” for this model, and AU/NZ parts catalogues from Tridon and Gates also specify a 0.9 bar (approx. 88 kPa) radiator cap for 2005–2012 Serena models. So yes, a radiator cap is used on the 2010 Nissan Serena, and it’s relevant to routine servicing—just note it’s located on the pressurised reservoir, not the radiator top tank.

On this Serena, the radiator cap’s job is to seal the cooling system and hold a set pressure (typically 0.9 bar). By raising the boiling point of the coolant, it helps prevent overheating under load, keeps coolant volume stable as temperatures swing, and allows excess pressure to vent to the overflow path when needed. A healthy cap also maintains vacuum as the engine cools, drawing coolant back to avoid air pockets.

Because the cap is effectively the system’s pressure regulator, it deserves a quick check at each service. A weak spring or perished seal can cause hard-to-trace issues like slow overheating, coolant loss via the overflow, collapsed hoses after cool-down, or gurgling on cold starts. In AU/NZ conditions, it’s sensible to replace the cap preventatively every 3–5 years or 60,000–100,000 km, or at the first sign of wear.

• Only remove the cap when the engine is stone cold. Hot systems can release scalding coolant under pressure.
• Inspect the rubber seals for nicks, flattening, or cracking, check the spring action feels firm and even.
• Wipe the reservoir neck clean so the new cap can seal properly, replace any brittle hoses nearby.
• Use the correct pressure rating (commonly 0.9 bar for Serena MR20DE) as stamped on the old cap or specified by a trusted parts catalogue or VIN lookup.
• If the system’s been open, bleed air following the service manual procedure and confirm the heater blows hot at idle.

For best results, pair the new cap with coolant that meets Nissan’s spec and keep to regular coolant changes. A quality OEM or reputable aftermarket cap (common in AU/NZ from brands like Tridon) will keep the Serena’s temperature right where it should be, even on long family runs or summer climbs.

Where is the radiator cap on a 2010 Nissan Serena?
It’s on the pressurised reservoir (expansion tank), not directly on the radiator. Look near the upper radiator hose area—there’s a plastic tank with a twist-off pressure cap on top.

What pressure rating cap does it use?
Most 2010 Serena MR20DE models use a 0.9 bar (about 88 kPa) cap. Always confirm by reading the stamping on the existing cap or checking a trusted parts catalogue against your VIN.

Can a faulty cap cause overheating or coolant loss?
Sure can. A weak or leaking cap can lower the system’s boiling point, push coolant into the overflow, pull in air as it cools, and even collapse hoses. If you’re chasing intermittent temperature spikes or unexplained coolant loss, start by testing or replacing the cap.