This is a non-pressure radiator cap (valveless type) designed for cooling systems that already use a separate pressure cap with spring (typically rated from 4 lb to 20 lb).
Unlike pressure caps, this cap contains no spring and no pressure valve. Its sole purpose is to act as a cold-fill access point, allowing the cooling system to be safely filled when cold while pressure regulation is handled elsewhere in the system.
Commonly used on commercial vehicles, agricultural machinery, plant equipment, classic vehicles, and Japanese cooling systems, these caps are an essential component in multi-cap cooling layouts.
Key Features
Non-pressure / valveless design
No spring – no pressure rating
Designed to be used in addition to a pressure radiator cap
Allows safe filling of the cooling system when cold
Durable metal construction for long service life
Suitable for automotive, commercial, agricultural, and industrial applications
Available Sizes & Materials
1️⃣ Large Commercial Type
Cap Diameter: 70 mm
Application: Commercial, plant & agricultural cooling systems
Construction: Heavy-duty Stainless Steel Case
2️⃣ Standard Size
Cap Diameter: 58 mm
Construction:Stainless steel case
Application: Automotive & industrial cooling systems
3️⃣ Small Japanese Type
Cap Diameter: 45 mm
Construction:Zinc-coated steel case
Application: Japanese vehicles, motorcycles, lawn equipment
Important Notes
❌ This is NOT a pressure cap
❌ No spring or pressure relief valve
✔ Must be used alongside a separate pressure radiator cap
