Introducing our 304 Stainless Steel Radiator Filler Necks, engineered for durability, precision fitment, and long-term corrosion resistance. Manufactured from high-grade 304 stainless steel, these filler necks are suitable for a wide range of automotive, motorcycle, commercial, and industrial cooling systems.
Available in three common sizes, each version is designed to match the correct radiator cap type and sealing depth, ensuring reliable pressure retention and proper coolant flow.
All dimensions shown in the images are provided to help confirm compatibility before purchase.
Available Sizes & Specifications
🔹 Large Commercial Filler Neck
Top Outside Diameter: 68 mm
Bottom Opening: 41.8 mm OD
Inside Depth: 19 mm
Overflow Outlet: Side spigot
Compatibility: Fits 70 mm commercial radiator caps
🔹 Small Japanese S-Type Filler Neck
Top Outside Diameter: 43.3 mm
Bottom Opening: 21.3 mm OD
Inside Depth: 16 mm
Overflow Outlet: Side spigot
Compatibility: Fits Japanese S-Type radiator caps
🔹 Standard Short Reach Filler Neck
Top Outside Diameter: 56 mm
Bottom Opening: 30 mm OD
Inside Depth: 20 mm
Overflow Outlet: Side spigot
Compatibility: Fits standard short-reach radiator caps
Key Features
Manufactured from 304 stainless steel for excellent corrosion resistance
Precision-formed for accurate cap sealing
Suitable for pressurised cooling systems
Side overflow outlet ready for hose connection
Ideal for custom builds, repairs, restorations, and motorsport applications
Important Notes
Photos are for size illustration only
Colours and finishes may vary slightly from images shown
Please match cap size and internal depth carefully before ordering
