Radium Engineering Coolant Expansion Tank (20-0270-00)

A V-mount or rear-mounted radiator cannot bleed itself, and trapped air is how cooling systems fail quietly.

When the radiator sits low or far from the engine, the highest point of the system needs to do the deaerating, and that is exactly what an expansion tank is for. The Radium Engineering Universal Coolant Expansion Tank is a 750mL, 2-piece CNC billet 6061 aluminum tank that becomes part of the pressurized coolant system, allowing the radiator to stay 100 percent full of coolant in all conditions. Inside, two connected chambers and a tangential-inlet vortex swirl feature spin incoming hot coolant to strip entrained air out of circulation. This is not an overflow bottle; it is the cooling system's air management brain.

What You'll Feel

• Reliable bleeding on V-mount, rear-radiator, and other unconventional layouts that trap air by design
• A radiator running completely full instead of carrying an air pocket for expansion
• Deaerated coolant circulating, with the swirl chamber spinning bubbles out of the flow
• A sight tube showing coolant level at a glance
• Real AN plumbing on ORB ports instead of clamped heater hose

Features

• 750mL capacity, 2-piece CNC billet 6061 aluminum construction with low-profile two-chamber design
• Internal chambers connected by crossover passages top and bottom; tangential vortex inlet swirl feature deaerates the system
• Billet aluminum neck accepts a standard 32mm "Mini" style pressure cap; cap must be Type-A seal style (sold separately)
• 2x bottom ports 10AN ORB, 1x front port 6AN ORB, with 6AN male adapter fittings included
• Kit includes anodized mounting bracket, 3x 6AN 90 degree Push-Lok hose ends, nickel-plated fittings and sight tube, 1/4" pressure bleed barb, and stainless hardware
• Part of the pressurized system, not a coolant overflow tank

The Details

Traditional cooling systems tolerate expansion by leaving air in the top of the radiator, which costs cooling capacity and becomes a real problem the moment the radiator is no longer the system's high point. This tank takes over that job: mounted at the highest point, it gives expansion its space, collects the system's air, and the swirl chamber accelerates hot coolant from the cylinder head into rotation so bubbles separate before the coolant returns to work. The ORB ports open real plumbing options, with the 10AN bottom ports feeding and returning main flow and the 6AN front port handling the head bleed or vent line, and Radium's full ORB adapter catalog fits when your routing needs something other than the included 6AN fittings. Cap selection matters twice: it must be a 32mm Type-A seal design, and choosing Radium's optional 1.1, 1.3, or 1.5 Bar stainless caps raises the system's boiling point for track duty. Cap sold separately.

Kit Includes

• 1x Billet aluminum coolant expansion tank with 32mm pressure cap receiver
• 1x Anodized aluminum mounting bracket
• 3x 6AN male adapter fittings and 3x 6AN 90 degree Push-Lok hose ends
• Nickel-plated fittings and sight tube
• 1x Aluminum 1/4" pressure bleed barb
• Stainless steel hardware
• Pressure cap NOT included; requires 32mm Type-A style cap

Applications

• Universal: V-mount, rear-mounted, and low-mounted radiator systems requiring proper air bleeding
• Also valuable integrated into common radiator setups for full-radiator operation
• Pairs with Radium 1.1/1.3/1.5 Bar Type-A pressure caps, sold separately