Mishimoto high-pressure radiator cap 1.3 bar (31–32 mm) — alloy steel, screw-in seal

Swap a weak or stock radiator cap for the Mishimoto MMRC-13-SM when you need a simple, durable upgrade that helps your cooling system tolerate higher temperatures and more demanding driving. Built from corrosion-resistant alloy steel with an ergonomic screw-in design and painted finish, this cap replaces typical factory units that aren’t intended for elevated pressures. It is engineered to fit most vehicle radiator necks sized 31–32 mm and installs without modifications.

How does this radiator cap improve cooling system performance?

By increasing the closed-system pressure to 1.3 bar (19 psi), the cap raises the coolant’s boiling point, giving the system more margin before vaporization occurs. That means less risk of localized boiling under hard driving or high ambient temperatures, which helps preserve coolant volume and consistent heat transfer.

• Increases system pressure to 1.3 bar (19 psi)
• Reduces likelihood of coolant boiling and vapor lock
• Maintains coolant volume under load for steadier temperatures

Will this cap fit my car’s radiator neck?

The MMRC-13-SM is designed for universal compatibility with standard 31–32 mm fill necks, making it suitable for a wide range of cars and light trucks. It will not fit KTM stock radiators; always verify your radiator neck diameter before ordering.

• Fits 31–32 mm standard radiator fill necks
• Simple swap — no cutting, adapters, or special tools required
• Confirm vehicle radiator neck size to ensure compatibility

What materials and design features ensure durability?

The cap’s body is machined from high-strength alloy steel and finished with a protective paint to resist corrosion and wear. A precision-threaded, screw-in design provides a tight seal, and the assembly is built to remain dependable through repeated removal and reinstallation.

• Corrosion-resistant alloy steel construction
• Painted finish for long-term protection
• Ergonomic screw-in shape for reliable sealing and easy handling

How easy is installation and everyday use?

Installation is straightforward: remove your existing cap and thread the Mishimoto cap into place. The ergonomic shape lets you install and remove the cap by hand; no special tools or mechanical modifications are necessary.

• Tool-free installation for most users
• OEM-style fitment and feel for seamless replacement
• Designed to hold seal after repeated removals

Who is this for: The Mishimoto MMRC-13-SM is aimed at drivers who push their cooling systems harder than stock conditions warrant — including performance builds, turbocharged vehicles, and owners in hot climates — as well as anyone wanting a robust OEM-style replacement cap. If your vehicle uses a 31–32 mm radiator neck and you want a corrosion-resistant, higher-pressure cap to increase boiling resistance and reduce coolant loss, this Mishimoto cap is a compact, reliable upgrade backed by a company known for thermal management components.