Flexfab 5581-350X12, 3.50" x 12 ft, 4-Ply Blue Silicone Coolant Hose, 89mm
Keep your cooling system sealed and reliable in the harshest engine bays with the Flexfab 5581-350X12 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 3.50" 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 200 PSI actual burst rating, which means a wide safety margin at the ~67 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.
- 3.50" (89mm) ID × 3.89" (99mm) 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 12-foot stick and ready to install, this hose pairs with a Flexfab 2582-0056 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: 5581-350X12
- Inside Diameter (ID): 3.50" (89mm)
- Outside Diameter (OD): 3.89" (99mm)
- Hose Length: 12 feet
- Wall Thickness: .170" / .220"
- Weight LB/FT: 1.37
- Actual Burst Pressure - PSI: 200
- SAE J20 R1 Class A - PSI: 75 PSI
- TMC RP303B Class I Grade II - PSI: 100 PSI
- Extreme temp range: -65F to +350F
- Construction: Blue Silicone hose with 4-ply of Polyester reinforcement