Parts for your 2013 Ford Focus-Radiator cap

2013 Ford Focus radiator cap — what’s actually on the car

Looking for a radiator cap on a 2013 Ford Focus under the bonnet and not seeing one? That’s because this model doesn’t use a traditional cap on the radiator neck. Ford engineered the Focus with a sealed, pressurised coolant expansion tank (also called a degas bottle), and the pressure cap lives on that reservoir instead. This layout is confirmed in Ford’s 2013 Focus Owner’s Manual under the engine cooling section, which tells owners to remove the pressure relief cap from the coolant reservoir for checks and top-ups, and in the Ford Workshop Manual cooling system overview that describes the remote-degas design.

Why no radiator-mounted cap? Modern cooling systems aim for consistent pressure control, cleaner emissions, and better packaging in tight engine bays. A remote tank with an integrated pressure cap helps the system “degas” (separate air from coolant) and keeps the highest point of the system at the reservoir. That makes air removal more reliable and reduces hot spots.

• Air separation and self-bleeding: The reservoir is the high point, so air migrates there naturally, reducing the chance of trapped bubbles.
• Stable pressure: The cap on the reservoir manages system pressure (typically around 20 psi/138 kPa for many Focus variants—check the cap label), protecting hoses, seals and the radiator.
• Safety and service: With no cap on the radiator itself, there’s less temptation to open a hot radiator. The labelled reservoir cap is the only service point.
• Packaging and durability: Fewer joints on the radiator mean fewer potential leak points and a more compact front-end design.

So while there’s no “radiator cap” per se, the coolant reservoir cap on the 2013 Ford Focus does the same critical job—holding pressure, raising the boiling point, and providing over-pressure relief. As part of routine servicing, it’s worth checking the reservoir cap’s seal and threads for wear, crusty deposits or coolant staining. Replace it if the seal looks flattened, cracked, or if you notice hard hoses after cool-down, frequent low coolant level, sweet smells, or overflow—classic signs of a weak cap not holding pressure. Only ever remove the cap when the engine is stone cold, and top up with the correct Ford-specified coolant mix for the vehicle. A quality, correct-pressure cap is cheap insurance for keeping the Focus’ cooling system healthy.

Popular questions about the 2013 Ford Focus “radiator cap”

Does a 2013 Ford Focus actually have a radiator cap?
The radiator itself doesn’t have a cap. Pressure control is handled by the cap on the coolant expansion tank (degas bottle). Ford’s owner and workshop manuals specify using the reservoir’s pressure relief cap for any coolant checks or top-ups.

What pressure rating should the coolant reservoir cap be?
Most 2013 Focus models use a cap around 20 psi (about 138 kPa), but the correct rating is printed on the cap. Using the wrong pressure cap can lead to boiling, leaks, or extra stress on hoses and the radiator, so match the rating to the original part.

When should the coolant cap be replaced?
If the seal is damaged, if the cap won’t hold pressure, or if there are recurring low-coolant warnings with no visible leaks, it’s time. Many owners pre-emptively replace the cap around major cooling service intervals or if there are overheating complaints after the system has been bled correctly.