D-Series Upper Coolant Fill Neck – AN16 Male Outlet

Proper cooling system maintenance starts with having a convenient and effective fill point. The Bull Boost Performance D-Series Upper Coolant Fill Neck is designed to relocate the coolant fill location to the highest point in the system, making coolant refills, air bleeding, and routine maintenance significantly easier.

Perfect for custom radiator installations, tucked engine bays, turbocharged setups, and race vehicles, this fill neck helps eliminate trapped air while promoting more efficient cooling system operation. The integrated design allows for simplified servicing while providing a clean, professional appearance under the hood.

Constructed from high-quality TIG-welded aluminum, this coolant fill neck features a standard radiator cap mounting flange, an integrated overflow fitting, and a male AN16 outlet for compatibility with a wide range of custom cooling system configurations.

Features

• Designed for D-Series engine applications
• Fits D16 engines
• AN16 male outlet for custom cooling system plumbing
• Standard radiator cap mounting flange
• TIG-welded aluminum construction
• Integrated overflow fitting included
• Lightweight and corrosion-resistant design
• Simplifies coolant filling and air bleeding
• Ideal for custom radiators and tucked cooling systems
• Perfect for street, race, turbocharged, and engine swap applications

Engineering & Construction

High-Quality Aluminum Construction

Manufactured from durable aluminum materials to provide long-lasting performance, corrosion resistance, and reduced weight.

TIG-Welded Assembly

Professionally welded for maximum strength, reliability, and leak-free operation under demanding conditions.

Optimized Cooling System Serviceability

Relocates the coolant fill point to improve system bleeding and help remove trapped air pockets commonly found in modified cooling systems.

Custom Cooling System Ready

Designed to work with AN16 plumbing commonly used in performance and motorsport cooling system configurations.

Specifications

• Material: Aluminum
• Finish: Silver
• Outlet Size: AN16 Male
• Overflow Port: Included
• Radiator Cap Compatibility: Standard Radiator Cap
• Construction: TIG Welded
• Condition: Brand New

Package Includes

• (1) D-Series Upper Coolant Fill Neck
• (1) Overflow/Vacuum Barb Fitting

Fitment

• Fits D16 engine applications
• Compatible with custom AN16 cooling system setups
• Suitable for custom radiator installations
• Ideal for tucked radiator configurations
• Designed for performance, racing, and engine swap projects

Installation Notes

Professional installation is recommended.

Please verify hose routing, fitting compatibility, and mounting hardware requirements prior to installation. Factory hardware may not be compatible with all applications.

The Bull Boost Performance D-Series Upper Coolant Fill Neck provides a clean, functional solution for custom cooling systems, making maintenance easier while improving the overall appearance and serviceability of your engine bay.