Automotive Unions and Connectors for Coolant, Fuel and Heater Hoses

Browse our range of high-quality aluminium and nylon unions designed to connect coolant, fuel, and heater hoses. This collection includes straight, 90°, and T-piece connectors in a variety of sizes — perfect for reliable plumbing in engine bays, heating systems and fuel lines.

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Smiths Classic Water Temperature Gauge - Magnolia Face - Chrome Bezel

Smiths Classic Water Temperature Gauge - Magnolia Face - Chrome Bezel

Monitor coolant temperature (50-140°C) with this classic Smiths 52mm electric gauge. Features magnolia dial, chrome bezel, and illumination.
£59.00
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CASTROL EDGE 5W-40 Fully Synthetic Engine OilCASTROL EDGE 5W-40 Fully Synthetic Engine Oil
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CASTROL EDGE 5W-40 Fully Synthetic Engine Oil

Advanced full synthetic engine oil for maximum performance and protection. Improves fuel economy and exceeds industry standards.
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  • Brass 3/8" UNF Single Male Brake Union - Car Builder SolutionsBrass 3/8" UNF Single Male Brake Union - Car Builder Solutions

    Brass 3/8" UNF Single Male Brake Union

    Durable brass brake union for 3/16" tubing, 3/8" UNF male thread, 17mm length. Secure and reliable connection.
    £1.20
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    £1.20
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  • Brass Brake T Piece M10 x 1 - Car Builder SolutionsBrass Brake T Piece M10 x 1 - Car Builder Solutions

    Brass Brake T Piece M10 x 1

    A reliable brass brake T-piece with concave seats, 9.5mm thread depth, and a 6.5mm mounting hole for secure connections.
    £9.00
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    £9.00
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  • Brass Brake T Piece 3/8" UNF - Car Builder SolutionsBrass Brake T Piece 3/8" UNF - Car Builder Solutions

    Brass Brake T Piece 3/8" UNF

    Durable Brass Brake T-Piece with 3/8" UNF threads, concave seats, and a 1/4" mounting hole.
    £9.00
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    £9.00
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  • Brass M10 x 1 Single Male Brake Union - Car Builder SolutionsBrass M10 x 1 Single Male Brake Union - Car Builder Solutions

    Brass M10 x 1 Single Male Brake Union

    A durable brass brake union for 3/16" tubing, ensuring secure and leak-free brake connections. Easy to install and built to last.
    £1.20
    £0.00
    £1.20
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  • 3/8" UNF Male Unions - Car Builder Solutions3/8" UNF Male Unions - Car Builder Solutions

    3/8" UNF Male Unions Pack of 10

    Durable steel 3/8" UNF male unions for 3/16" copper/nickel pipe. 11mm hex, 16mm thread length. Pack of 10.
    £4.20
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    £4.20
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  • Brass 3/8" UNF Single Female Brake Union - Car Builder SolutionsBrass 3/8" UNF Single Female Brake Union - Car Builder Solutions

    Brass 3/8" UNF Single Female Brake Union

    A durable brass 3/8" UNF single female brake union, ideal for 3/16" brake tubing. Ensures a secure and leak-free connection for optimal braking performance.
    £1.80
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    £1.80
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  • Brass 7/16" Male Union for 3/16" Pipe - Car Builder Solutions

    Brass 7/16" Male Union for 3/16" Pipe

    Durable brass male union for joining 3/16" copper/nickel pipe securely. 7/16" thread, 16mm depth.
    £1.80
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    £1.80
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  • Brass M10 x 1 Male Blanking Plug - Car Builder SolutionsBrass M10 x 1 Male Blanking Plug - Car Builder Solutions

    Brass M10 x 1 Male Blanking Plug

    Brass blanking plug for sealing M10 x 1 female unions. Durable construction with a 17mm thread length for secure fastening.
    £2.40
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    £2.40
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  • Brass M10 x 1 Bulkhead Brake Union - Car Builder Solutions

    Brass M10 x 1 Bulkhead Brake Union

    Brass bulkhead brake union, connects copper brake pipe to flexible hoses at chassis, M10 x 1 half nut included, male flares, 48mm length.
    £7.80
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    £7.80
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  • Brass M10 x 1 Metric Female Blanking cap - Car Builder Solutions

    Brass M10 x 1 Metric Female Blanking cap

    Brass blanking cap seals unused M10 x 1 male ports. Prevents leaks, protects ports, ensures system integrity. Durable and easy to install.
    £2.40
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    £2.40
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  • Brass Brake 4 Way 3/8" UNF - Car Builder SolutionsBrass Brake 4 Way 3/8" UNF - Car Builder Solutions

    Brass Brake 4 Way 3/8" UNF

    Durable brass 4-way brake tee with 3/8" UNF threads, concave seats, and precise measurements for secure braking performance.
    £12.00
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    £12.00
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  • Brass 3/8" UNF Male Blanking Plug - Car Builder SolutionsBrass 3/8" UNF Male Blanking Plug - Car Builder Solutions

    Brass 3/8" UNF Male Blanking Plug

    Solid brass blanking plug for sealing unused 3/8" UNF female ports with a secure, leak-proof closure.
    £1.80
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    £1.80
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  • 3/8" UNF Female Brake Unions - Car Builder Solutions3/8" UNF Female Brake Unions - Car Builder Solutions

    3/8" UNF Female Brake Unions Pack Of 10

    Pack of 10 plated steel brake unions. 3/8" UNF thread, fits 3/16" copper/nickel pipe. 17.5mm long, 13mm hex. Concave seat.
    £4.20
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    £4.20
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  • Brass 3/8 UNF Bulkhead Brake Union - Car Builder Solutions

    Brass 3/8" UNF Bulkhead Brake Union

    Brass bulkhead brake union for connecting brake pipes to flexible hoses. 3/8" UNF thread, includes brass half nut. 48mm length.
    £7.80
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    £7.80
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  • Stainless Steel M10 x 1 Male Brake Union - Car Builder SolutionsStainless Steel M10 x 1 Male Brake Union - Car Builder Solutions

    Stainless Steel M10 x 1 Male Brake Union

    Durable stainless steel M10 x 1 male brake union for 3/16" pipe. Secure, leak-free connection for braking systems.
    £4.32
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    £4.32
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  • Brass Brake 4 Way M10 x 1 - Car Builder SolutionsBrass Brake 4 Way M10 x 1 - Car Builder Solutions

    Brass Brake 4 Way M10 x 1

    A durable brass brake 4 way union with concave seats, an 11.5mm thread depth and 6.5mm mounting hole for secure brake connections.
    £15.00
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    £15.00
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  • Brass M10 x 1 Single Female Brake Union - Car Builder SolutionsBrass M10 x 1 Single Female Brake Union - Car Builder Solutions

    Brass M10 x 1 Single Female Brake Union

    Brass brake union for 3/16" tubing. Secure, leak-free connection. 17mm long, 11mm thread depth. M10 x 1 female thread.
    £1.80
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    £1.80
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  • Brass 7/16" Male Union For 1/4 Pipe - Car Builder SolutionsBrass 7/16" Male Union For 1/4 Pipe - Car Builder Solutions

    Brass 7/16" Male Union For 1/4 Pipe

    Durable 7/16" brass male union, ideal for 1/4" copper/copper-nickel pipe. Secure, leak-free connection for plumbing/heating.
    £1.80
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    £1.80
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  • Brass Union 1/8" NPT male to M10 x 1mm female - Car Builder SolutionsBrass Union 1/8" NPT male to M10 x 1mm female - Car Builder Solutions

    Brass Union 1/8" NPT male to M10 x 1mm female

    Brass adaptor providing secure connection between 1/8" NPT male and M10 x 1mm female threads. Durable, reliable and easy to install.
    £5.40
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    £5.40
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  • Brass Union 3/8" UNF Male to 7/16" UNF Female

    Brass Union 3/8" UNF Male to 7/16" UNF Female

    Brass union adapting 3/8" UNF male to 7/16" UNF female for plumbing and automotive applications.
    £9.00
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    £9.00
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  • 7/16" UNF Female Brass Union with 8mm Hosetail - Car Builder Solutions7/16" UNF Female Brass Union with 8mm Hosetail - Car Builder Solutions

    7/16" UNF Female Brass Union with 8mm Hose Tail

    Brass union for brake fluid reservoirs, 7/16" UNF female thread with 8mm hose tail. Durable and easy to install.
    £10.20
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    £10.20
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  • Brass Union 7/16" UNF MALE to 3/8" UNF Female - Car Builder SolutionsBrass Union 7/16" UNF MALE to 3/8" UNF Female - Car Builder Solutions

    Brass Union 7/16" UNF MALE to 3/8" UNF Female

    Concave seat in female end.
    £9.00
    £0.00
    £9.00
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  • Stainless Steel 3/8" UNF Male Brake Union - Car Builder SolutionsStainless Steel 3/8" UNF Male Brake Union - Car Builder Solutions

    Stainless Steel 3/8" UNF Male Brake Union

    Durable stainless steel 3/8" UNF male brake union for 3/16" copper/nickel brake pipe. Secure, leak-free connection. 21.5mm length.
    £4.32
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    £4.32
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  • In-Line Connector M10 Female - Car Builder Solutions

    In-Line Connector M10 Female

    M10 female in-line connector, secure, reliable, leak-free, easy installation. Perfect for various applications.
    £1.80
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    £1.80
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  • In-Line Connector 3/8" UNF Female to 3/8" UNF Female - Car Builder Solutions

    In-Line Connector 3/8" UNF Female to 3/8" UNF Female

    Solid brass 3/8" UNF female connector union, ideal for various plumbing applications. Durable and reliable.
    £3.60
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    £3.60
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FAQs

Got a question? We are here to answer

Hose Connection Solutions for Custom Plumbing

Unions are vital for joining sections of coolant or fuel hose, especially when adding remote fillers, header tanks, or heater valves. Choose from high-flow, compact, and decorative finishes to suit your engine bay setup.

Featured Products in This Collection

Common Applications

  • Heater hose extensions and bypass circuits
  • Coolant reroutes and header tank feeds
  • Fuel return and breather unions

Useful Videos

How to Make Your Own Copper Brake Lines for Your Car

All hose unions are in stock and available with next day UK delivery. Build your plumbing with durable, reliable connectors.