Crafted from high-quality brass, our radiator filler necks are designed for durability, reliability, and a professional finish on custom or replacement cooling systems. Suitable for classic, Japanese, commercial, and custom-built applications, each neck is precision formed to ensure correct cap fitment and long-term sealing performance.These filler necks can be
soft soldered or silver soldered, making them ideal for radiator repairs, restorations, and bespoke fabrication projects.
Available Sizes & Specifications
Large Commercial Filler Neck
- Top Outside Diameter: 68mm
- Bottom Opening: 41.8mm OD
- Inside Depth: 19mm
- Overflow Outlet Included
- Fits 70mm commercial radiator caps
Standard Long Reach Filler Neck
- Outside Diameter: 56mm
- Opening: 30mm OD
- Inside Depth: 26mm
- Overflow Outlet Included
- Fits standard long-reach radiator caps
Standard Short Reach Filler Neck
- Outside Diameter: 56mm
- Opening: 30mm OD
- Inside Depth: 20mm
- Overflow Outlet Included
- Fits standard short-reach radiator caps
Small Japanese S-Type Filler Neck
- Top Outside Diameter: 43.3mm
- Bottom Opening: 21.3mm OD
- Inside Depth: 16mm
- Overflow Outlet Included
- Fits Japanese S-type radiator caps
Key Features
- Manufactured from solid brass
- Suitable for soft soldering or silver soldering
- Precision-formed for correct cap sealing
- Ideal for cars, motorcycles, plant, agricultural, and custom builds
- Supplied as bare brass finish
- Photos show size reference – colour may vary slightly
Applications
- Radiator repairs
- Custom radiator fabrication
- Classic and vintage vehicles
- Japanese vehicle cooling systems
- Commercial and agricultural machinery
Need Help Choosing the Correct Size?If you are unsure which filler neck matches your radiator cap or application, please contact us before ordering — we are happy to advise.
