EVIL ENERGY 3/8" Heater Hose Coolant Radiator Straight

EVIL ENERGY 3/8" heater hose is a 10-foot EPDM coolant line built to SAE 20R3 standards for radiator, overflow, and hot-water system connections.

This straight 3/8" (9.5 mm) heater hose from EVIL ENERGY is designed for automotive and small-engine cooling circuits that need a durable, flexible conduit for coolant, water, and antifreeze. Constructed from EPDM rubber with industry-standard tolerances, it delivers a balance of heat and cold resistance, pressure capacity, and bendability for repair, replacement, or custom plumbing projects.

How reliable is this hose for engine cooling systems?

The EVIL ENERGY heater hose meets SAE 20R3 Standard Wall Class D-2 and is rated for a working pressure of 100 psi with a 300 psi burst pressure, giving a broad safety margin for typical automotive cooling conditions. EPDM construction provides proven resistance to hot coolant and common additives, and the specified temperature range covers severe winter and summer environments.

• Working pressure: 100 psi; burst pressure: 300 psi
• Temperature range: -40°F to 257°F for seasonal durability
• Meets/exceeds SAE 20R3 D-2 standard for heater hose use

Will the size and flexibility work in tight engine compartments?

This hose has a nominal inner diameter of 3/8" (9.5 mm) with ±0.4 mm tolerance and an outer diameter of 5/8" (16 mm) with ±0.5 mm tolerance, making it compatible with common small coolant fittings. The minimum bending radius is 76 mm, allowing smooth routing around brackets and components without kinking when installed correctly.

• Inner diameter: 3/8" (9.5 mm) with tight tolerance
• Outer diameter: 5/8" (16 mm) for predictable clamp fit
• Min bending radius: 76 mm to avoid sharp bends and stress

What liquids and environments can this hose handle?

Made from EPDM rubber, the hose is compatible with coolant, water, antifreeze blends, and many non-pressurized fluid mixtures commonly found in heating and cooling systems. Its material resists heat, ozone, and many automotive fluids, making it suitable for both engine bay and hot water heater applications when used within its specified limits.

• Compatible media: coolant, antifreeze, water
• Material benefits: EPDM resists heat, ozone, and aging
• Applications: radiator-to-overflow, heater core, hot water heater piping

How should I cut, fit, and secure this hose for a clean installation?

Cut the hose squarely with a sharp utility knife or hose cutter to ensure proper sealing and even clamp pressure. Use the correct-size clamps for the 5/8" outer diameter and avoid overtightening; allow for routing that respects the 76 mm minimum bend radius to reduce stress and premature wear.

• Length: 10 feet of continuous hose for multiple runs or custom cuts
• Cutting: clean, square cuts improve sealing with clamps
• Clamping: use appropriate-size clamps, tightened to manufacturer recommendations

Who is this for? This EVIL ENERGY 3/8" heater hose is aimed at DIY mechanics, automotive technicians, restoration builders, and HVAC installers who need a dependable, standards-compliant coolant line for small-bore connections. It's especially useful when you require a long continuous length (10 feet) to supply multiple runs, replace damaged hose sections, or fabricate custom coolant plumbing. If you need EPDM resilience, predictable dimensions, and SAE 20R3 performance in a compact heater hose, this product fits those requirements.