Finding the right 5/8″ heater hose with a 90 degree bend matters for fit, durability, and heat resistance. Below is a quick comparison table of top picks, followed by focused product sections and a detailed buying guide to help you choose the correct hose for automotive heater, coolant, and swap applications.
| Product | Brand | Key Feature |
|---|---|---|
| Heater Hose w/90 Degree Bend, 5/8″ ID, 4″x36″ #91-0012H-36 | Old Air Products | Flexible, long lasting |
| 2Pcs 5/8” Heater Hose 90 Degree Elbow (16mm) | KH866 | 3-ply reinforced silicone, universal fit |
| LS Swap Heater Hose Set 90 Degree Molded | BLACKHORSE-RACING | Molded for tight LS engine bay clearance |
| For LS Swap Heater Silicone Hose 5/8 ID 90 Degree | XRTMD | LS swap specific, includes clamps |
| Dayco 80402 90-Degree 5/8” Molded Coolant/Heater Hose | DAYCO | Heavy duty, burst resistance |
Old Air Products 5/8″ ID 90° Heater Hose
This molded heater hose from Old Air Products is specified as 5/8″ inner diameter with a 90° bend and a 4″ by 36″ overall length. The listed features emphasize very flexible material and long-lasting durability. Flexibility can ease installation in confined engine bays and reduce stress at fittings. Durability claims imply resistance to common coolant and heat exposure in heater circuits. Use cases include replacement of original heater hoses or custom routing where a pre-formed 90° section avoids kinks.
KH866 2Pcs 5/8″ 90° Elbow Heater Hoses
The KH866 set includes two 5/8″ (16mm ID) 90° elbow heater hoses made from reinforced silicone with a 3-ply construction. The product is described as a universal fit that can be trimmed to length, and it highlights high temperature resistance suitable for coolant and turbo applications. The reinforced layers provide improved strength for higher pressure and temperatures compared with simple rubber hoses. This set is appropriate for retrofit work, repairs, or areas where silicone’s heat tolerance is preferred.
BLACKHORSE-RACING LS Swap 90° Molded Hose Set
Designed for LS engine swaps, the BLACKHORSE-RACING molded hoses are offered in both 5/8″ and 3/4″ IDs with 90° bends and a 4″ x 24″ length. The product notes emphasize use where tight clearance on the passenger side of the engine bay is a concern and where factory heater outlet placement interferes with suspension or bodywork. Molded geometry provides consistent bend radius and repeatable routing, reducing the chance of kinks or rubbing against nearby components.
XRTMD For LS Swap 5/8″ ID Silicone 90° Hose
This XRTMD silicone hose targets LS swaps and lists fitment for LS1, LSX, LS2, LS3, LQ4, and LQ9 engines. The product description highlights suitability for tight passenger-side clearance issues and notes that it comes with two clamps. Silicone construction typically offers improved resistance to heat and ozone compared to conventional EPDM rubber, which can benefit longevity in high-temperature engine bays. Molded 90° geometry helps maintain flow while simplifying installation in swap applications.
Dayco 80402 90° 5/8″ Molded Coolant/Heater Hose
Dayco’s molded 90° heater hose is an 18-inch curved unit with heavy-duty construction aimed at resisting road debris, coolants, salt, and temperature variations. The manufacturer lists a burst resistance guarantee for the life of the hose. As an OE-focused supplier, Dayco commonly uses materials and reinforcement suited to long-term durability in factory-style coolant circuits. This hose is appropriate where robust, service-proven molded components are required.
Buying Guide: Choosing The Right 5/8″ 90° Heater Hose
Selecting the correct 5/8″ heater hose with a 90° bend requires attention to fit, materials, and application conditions. The sections below outline the main considerations to evaluate before buying.
Inner Diameter And Fitment
Confirm the hose inner diameter is 5/8″ (16mm) when replacing factory lines. Some swap kits include both 5/8″ and 3/4″ pieces—verify the correct size for the heater core and water pump outlets. For universal hoses, trimming may be required but ensure clamp seating length is maintained.
Bend Geometry And Length
Molded 90° hoses provide a consistent bend radius that reduces kinking. Consider the exact bend orientation and overall length—pre-formed hoses eliminate guesswork, while straight silicone elbows trimmed to fit offer flexibility in routing. Measure clearance to nearby suspension, bodywork, or other engine components to avoid abrasion.
Material: Rubber vs Silicone vs Reinforced
- EPDM/Rubber: Common for OEM applications; good general resistance to coolant and temperature variations.
- Silicone: Better high-temperature and ozone resistance; often used in performance or swap applications.
- Reinforced/3-Ply: Adds pressure resistance and tensile strength—useful in turbo or high-heat contexts.
Temperature And Pressure Ratings
Check manufacturer specifications for maximum continuous temperature and burst pressure where available. Hoses near exhaust components or turbochargers require higher heat resistance. Reinforced hoses typically have higher pressure tolerance.
Installation And Hardware
Look for included clamps for a complete installation. If clamps are not included, purchase quality worm-drive or T-bolt clamps sized for 5/8″ hose. Ensure there is adequate hose overlap on fittings and avoid overtightening clamps which can cut silicone or rubber.
Application Specifics: Swap & OEM Replacement
For LS swaps and other engine conversions, choose hoses molded for tight clearances or that explicitly list compatibility with the target engine family. For OEM replacements, prefer hoses designed for factory geometry or from established OE suppliers for fit reliability.
Durability And Environmental Resistance
Consider exposure to road salt, coolant types (e.g., ethylene glycol, propylene glycol), and potential contact with gasoline or oil. Some nitrile or specialized blends are needed for fuel exposure; for heater hoses carrying coolant, EPDM or silicone is standard.
Comparison Perspectives
- Performance/High-Heat: Reinforced silicone elbows (e.g., KH866) are preferable.
- OEM-Look/Durability: Dayco molded hoses aim to match factory expectations with heavy-duty construction.
- Swap-Specific Fit: Molded LS swap hoses (BLACKHORSE-RACING, XRTMD) ease routing in tight engine bays.
- Cost vs Custom Fit: Universal elbows trimmed to length provide flexibility but may require additional clamps; molded hoses reduce trial-and-error fitment issues.
Installation Tips
- Drain coolant to a safe level before removing old hoses and capture fluid properly.
- Compare new hose geometry to the old unit to confirm bend orientation and length.
- Clean mating surfaces and fittings to prevent leaks when installing new hoses and clamps.
- Use new clamps and torque them to recommended values; check for movement after heat cycles.
- Pressure test the cooling system and inspect for leaks after installation.
Maintenance And Replacement Signs
Replace hoses showing swelling, cracks, soft spots, deformation at bends, or coolant leakage. Also replace hoses at preventive intervals if vehicle is older or exposed to severe conditions. Inspect clamps and adjacent components for rubbing or abrasion that could shorten hose life.