4 lb / PSI Stainless Radiator Pressure Cap & 56 mm Stainless Filler Neck 


Standard short-reach 304 stainless steel radiator filler neck supplied with a low-pressure 4 lb stainless cap—ideal for custom builds and specialist cooling systems.

⚠️ Important Fitting / Welding Note

The 8 mm overflow pipe is supplied loose and must be welded into position when fitting the filler neck to the tank.

This is intentional to ensure a clean weld and avoid contamination from pre-attached parts.

Item Description

This stainless radiator filler neck and cap set is designed for reliable sealing on pressurised cooling systems where a low-pressure cap is required. Manufactured from grade 304 stainless steel for corrosion resistance and durability, suitable for welding to a radiator or header tank.

Neck Sizes

Top Diameter (cap twist-on) 56 mm
Inner Depth 20 mm
Collar 42.5 mm
Bottom Hole (seats into tank) 29.5 mm
Wall Thickness 0.9 mm

Standard short-reach neck. Please measure your existing filler neck to confirm compatibility before purchase.

Pressure Cap

  • Pressure Rating: 4 lb / PSI
  • Outside Diameter: 60 mm
  • Reach: Short reach
  • Compatibility: Fits filler neck listed above

Material

  • Neck: 304 Stainless Steel
  • Cap Case: 304 Stainless Steel
Shipping & Dispatch
  • Stock items: Dispatched in 1–2 working days.
  • Made-to-order / custom items: Dispatched in 2–4 working days.
Smooth Checkout

Enjoy a smooth checkout process. Please ensure the pressure rating and neck dimensions are suitable for your application before ordering.

Customer Support

We are at your side both before and after the purchase with words and deeds. Contact us using the eBay contact form and we will get back to you as soon as possible.

Returns

30 Day Returns. Items must be returned unused and in original condition where possible.

Thank you for your business.