The radiator cap featured in this article (part number 145030) is the type used on a wide range of Ferrari models from the F355 onward.
It is available from our online store. For ordering, availability, pricing, and other details, please check 👉here.
How a Radiator Cap Is Constructed
To examine the construction and operation of the radiator cap, we cut open a brand-new part (a bit of a shame, we know!) and inspected the components inside.
Cross-Sectional View
Inside the cap are a pressure spring and valve that maintain the cooling system at its specified pressure. It also contains a return valve that operates when the internal pressure drops after the system cools down.
In other words, a radiator cap is more than just a lid. It is a mechanical component that regulates pressure within the cooling system and manages coolant flow.
Components
The radiator cap consists of the components shown in the photo below.
① Outer housing
② 1.0 bar pressure spring
③ Valve and seal
④ Return valve and spring
⑤ Inner housing
⑥ Gasket
As shown here, the radiator cap does more than prevent coolant leakage. It also incorporates a valve mechanism that maintains the pressure inside the cooling system within a specified range.
How Radiator Caps Deteriorate with Age
A radiator cap is often regarded simply as the lid for a coolant reservoir or radiator. In reality, however, it is continuously exposed to demanding conditions such as:
- Heat transferred from the engine
- Contact with coolant
- Repeated pressurization and depressurization of the cooling system
- Vibration while driving
The seals and gasket around the valve, together with the spring that controls pressure, are particularly susceptible to deterioration.
As the years and mileage accumulate, the rubber components may harden or become compressed and lose their elasticity. This can weaken the seal where the radiator cap meets the housing.
Problems with the pressure spring or valve operation may also prevent the cooling system from maintaining its specified pressure or releasing pressure correctly when necessary.
Pressurizing the cooling system serves the important purpose of raising the coolant’s boiling point and helping to prevent it from boiling. If deterioration of the spring or valve prevents the system from maintaining pressure, it may affect the condition and performance of the cooling system.
Preventive Replacement / Spare Part
The gasket, spring, valve, and other components inside a radiator cap deteriorate through use.
However, it is not always easy to determine exactly when a radiator cap needs to be replaced.
- A coolant leak may occur suddenly
- Insufficient system pressure can be difficult to notice during normal driving
- The internal gasket or spring may have deteriorated even when there are no visible signs of a problem
For these reasons, if the cap has been in use for a long time or the cooling system is being serviced, we recommend inspecting its condition and considering preventive replacement.
It can also be reassuring to carry a radiator cap suitable for your vehicle as a spare when taking a long trip or driving a long distance. If a cap-related coolant leak or pressure problem occurs while you are away from home, replacing it with the spare cap may provide a solution.
However, replacing the cap will not resolve a coolant leak caused by another component, such as a hose or tank. If a problem occurs, allow the engine to cool completely before checking its condition, and consult a specialist workshop if necessary.
Compatible Models
Ferrari
・355
・360
・F430
・458
・488
・550
・575 and others
Online Store
We regularly stock this radiator cap.
This Italian aftermarket part is available for approximately half the price of the genuine part. Its reasonable price makes it an excellent choice for preventive replacement or as a spare. Click the image below to order or check availability.
Please feel free to contact us with any questions or enquiries about other parts.
Contact Us
Contact Form
Email: importparts@italycar.jp
Contact: Mitsunori Ninomiya
Diapalace Momoyama 302
3-1619-2 Momoyama, Midori-ku
Nagoya City, Aichi
Zip code: 458-0002
Japan