Parts for your 2013 Mazda Bt-50-Radiator cap

2013 Mazda BT‑50 radiator cap – is there one, and where?

The 2013 Mazda BT‑50 (UP/UR series) doesn’t use a traditional radiator‑neck cap on the radiator itself. Instead, it runs a modern pressurised expansion tank (also called a degas or surge bottle) with the pressure cap fitted to that tank. The radiator is a sealed unit without a filler neck. This setup is confirmed in the Mazda BT‑50 UP/UR Workshop Manual cooling system component diagrams and description, and aligns with the shared Ford Ranger PX platform design outlined in the Ford Workshop Manual’s Engine Cooling (303‑03) section.

Why no “radiator cap” then? The cooling system is designed to keep the highest point of the circuit at the expansion tank under the bonnet. That means air can continuously separate and be purged into the tank, which helps prevent hot spots and makes bleeding after coolant changes far simpler. The pressure cap on the expansion tank still does the classic cap jobs—raising the boiling point by holding system pressure and allowing vacuum return as the engine cools—but it’s located where it can manage both filling and de‑aeration. Packaging is better too: a sealed radiator improves durability and crash performance, while the remote tank provides a safe, accessible fill point away from the fan and shrouds.

For owners shopping under the term “radiator cap,” it’s worth noting that on a 2013 BT‑50 the part you’re after is the pressure cap that fits the expansion/degas tank, not the radiator. When servicing, the basics still apply: only open the cap when the engine is fully cool, check the rubber seals and spring for wear or deformation, and replace the cap if there are signs of coolant weeping around the tank neck, collapsed hoses after cool‑down, or recurring overflow. Use the correct pressure rating as specified by Mazda for the BT‑50 engine variant (this is listed in factory literature and under‑bonnet labels). Mixing caps with the wrong pressure can cause premature hose or tank failure, or allow boil‑over on heavy towing runs in Aussie or Kiwi summer heat.

Referenced technical sources:

• Mazda BT‑50 (UP/UR, 2011–2018) Workshop Manual – Cooling System: Component Location and System Description
• Mazda Electronic Parts Catalogue (EPC) – Cooling System Illustrations for UP/UR: radiator shown as sealed, cap specified on expansion tank
• Ford Ranger PX Workshop Manual – 303‑03 Engine Cooling: remote pressurised degas bottle design (shared platform)

Popular questions

Where is the radiator cap on a 2013 Mazda BT‑50?

It’s on the pressurised expansion (degas) tank, not on the radiator. Look for the plastic reservoir on the passenger‑side front of the engine bay with a warning label on the cap. The radiator itself does not have a removable cap.

What pressure cap does a 2013 BT‑50 use?

The BT‑50 uses a specific pressure rating matched to the engine and cooling system. Always check the owner’s manual, under‑bonnet decals, or a trusted parts catalogue for the correct kPa/psi rating for the UP/UR model. Using the wrong rating can lead to overheating or undue stress on hoses and the tank.

What are the signs the BT‑50’s coolant reservoir cap needs replacing?

Common clues include coolant staining or weeping around the cap, hoses that collapse flat after cool‑down, regular coolant loss with no external leaks, or overheating under load. If any of these show up, test or replace the cap and inspect the tank neck for damage.