Flexfab 5581-100, 1.00" x 3 ft, 4-Ply Blue Silicone Coolant Hose, 25mm

Keep your cooling system sealed and reliable in the harshest engine bays with the Flexfab 5581-100 4-ply silicone coolant hose. A versatile heavy-duty coolant hose for diesel, automotive, marine, agricultural, and industrial cooling systems — including city transit, school buses, and refuse fleets — this 1.00" ID hose resists the hardening, cracking, and aging that cut the life of ordinary rubber hose — so you replace it less and trust it more.

Why this Flexfab 4-ply coolant hose

• 4-ply polyester reinforcement — delivers a 550 PSI actual burst rating, which means a wide safety margin at the ~183 PSI working pressure of most cooling systems.
• −65°F to +350°F range — silicone construction stays flexible in winter cold and holds up to under-hood heat, so it won’t go brittle or soften.
• Meets SAE J20 R1 Class A & TMC RP303B Class I Grade II — spec-grade performance fleets can document and rely on.
• 1.00" (25mm) ID × 1.39" (35mm) OD, .170"/.220" wall — precise sizing for a clean clamp seal.
• Resists oil splash, ozone, and direct sunlight — engineered for long service life in hostile engine environments.

Cut to a 3-foot stick and ready to install, this hose pairs with a Flexfab 2582-0016 clamp for a leak-free connection that handles repeated heat cycles without loosening.

Backed by hpcouplers’ fast shipping and easy returns — order with confidence from a trusted industrial hose and coupler supplier.

• FlexFab Series: 5581
• Part Number: 5581-100
• Inside Diameter (ID): 1.00" (25mm)
• Outside Diameter (OD): 1.39" (35mm)
• Hose Length: 3 feet
• Wall Thickness: .170" / .220"
• Weight LB/FT: 0.39
• Actual Burst Pressure - PSI: 550
• SAE J20 R1 Class A - PSI: 300 PSI
• TMC RP303B Class I Grade II - PSI: 125 PSI
• Extreme temp range: -65F to +350F
• Construction: Blue Silicone hose with 4-ply of Polyester reinforcement