Parts for your 2017 Ford Fiesta-Radiator cap

2017 Ford Fiesta radiator-cap: what’s actually fitted

Chasing a “radiator-cap” for a 2017 Ford Fiesta? Technically, this model doesn’t run a traditional cap on the radiator at all. Instead, Ford designed the Fiesta’s cooling system as a sealed, pressurised setup that fills and vents through a plastic coolant reservoir (also called a degas or expansion bottle). The pressure cap lives on that reservoir, not on the radiator.

This layout is described in Ford’s service literature: the Ford Workshop Manual (WSM, Section 303-03 Engine Cooling) specifies a closed system with a degas bottle, and the 2017 Fiesta Owner’s Manual tells owners to remove the “coolant reservoir cap” only when the engine is cool. There’s no instruction to open a radiator cap because there isn’t one fitted from factory.

Why did Ford ditch the old-school radiator-cap on the neck of the radiator? A few solid reasons:

• Packaging and safety: modern front ends sit the radiator low and tucked away. A single, high-mounted reservoir makes topping up easier and helps keep hot, pressurised coolant away from hands and paintwork.
• Better air management: the reservoir acts as a high point to purge air, cutting the risk of hot spots and improving cooling efficiency.
• Fewer leak points: one cap on the bottle means fewer seals and joints to weep over time.

So, if someone’s shopping for a “radiator-cap” for a 2017 Fiesta, the correct part to look for is the coolant reservoir pressure cap. It sits on the translucent plastic bottle in the engine bay. The cap’s pressure rating is printed on its top, confirm that rating and match it when replacing. Ford genuine parts catalogues list this as the reservoir/degas bottle cap for the Fiesta, and the Owner’s Manual specifies using the approved coolant and opening the cap only when the engine is cold.

General care is simple: keep an eye on the cap’s seal, make sure the spring moves smoothly, and replace the cap if there’s staining, crusty coolant residue, or a sweet coolant smell under the bonnet. When refilling or bleeding after service, follow the procedure in Ford’s WSM: fill via the reservoir, run the heater, and check for stable level once cool.

• Popular questions

Does a 2017 Ford Fiesta have a radiator-cap?
No—there’s no cap on the radiator itself. The vehicle uses a sealed cooling system with a pressure cap on the coolant reservoir (degas bottle). Ford’s 2017 Fiesta Owner’s Manual and Workshop Manual both reference opening the “coolant reservoir cap,” not a radiator cap.

Which cap should be bought for a 2017 Fiesta?
Buy a coolant reservoir pressure cap that matches the rating printed on the original cap. Genuine Ford or quality aftermarket equivalents are fine. If the seal looks perished, the spring is weak, or there are signs of leakage, replacement is due. It’s smart to inspect it at each service.

Is it safe to open the cap to top up coolant?
Only when the engine is fully cool. Crack the reservoir cap slowly to relieve any residual pressure. Top up with Ford-approved coolant as specified in the Owner’s Manual and recheck the level after a drive cycle once the engine cools again.