Mishimoto Radiator Hoses for 00-09 Honda S2000

Mishimoto Silicone Radiator Hose Kit for 00-09 Honda S2000 (AP1/AP2)

Radiator hoses don't usually fail all at once. They age. Years of heat soak bake the rubber until it's hard and starts cracking at the bends, or goes soft and swells near the clamps. On an S2000, where the F20C and F22C live at high RPM and the engine bay runs hot, a 20-year-old hose is a gamble. When one finally lets go, you lose your coolant fast. And on an engine that revs this hard, overheating does damage quickly.

This Mishimoto kit replaces both main radiator hoses, upper and lower, with black silicone versions in the factory shape. Same route, same connections, so there's nothing to rework. If the radiator's coming out anyway, it's the right time to do it. You don't have to go silicone, though. A good molded rubber replacement is a perfectly good choice for a stock S2000. Silicone makes the most sense if you want hoses that stay flexible through years of heat. In black, they blend into the engine bay the way the factory hoses did.

Silicone vs. Rubber

Most OE-style coolant hoses are EPDM, a synthetic rubber that handles heat, ozone, and coolant well when it's made right. Over time, though, heat still hardens it. Silicone stays flexible far longer under the same heat, which is the main reason to switch. Mishimoto reinforces the hose wall with embedded heat-resistant fibers so it holds its shape under pressure. Good rubber hoses are reinforced too, so the reinforcement alone isn't a reason to switch. It's the silicone plus the reinforcement together. Mishimoto rates these hoses to 330°F. That's how much heat the hose itself can take. It doesn't add any cooling capacity, and it doesn't change which radiator cap your car should run.

The Trade-Off: Permeation

Silicone lets a little more water pass through the hose wall than rubber does. It's slow, and it's not a leak, but over time the coolant level can drop a bit more than you're used to. Check it as part of your normal maintenance and top it off as needed. If you ever see coolant dripping or a wet spot on the hose, that's a real leak, not permeation, so track it down.

Clamps Matter More with Silicone

Silicone is softer than rubber, and the slots in a standard worm-drive clamp can cut into it when you tighten it down. If you're using worm-drive clamps, get ones with a smooth inner band or a shield that covers the slots under the screw. Size each clamp to the hose and fitting, and tighten it to the clamp maker's spec. Don't just crank it down harder to stop a weep. Silicone can also settle a bit after the first few heat cycles, so check the clamps again after a few drives. Clamps aren't included in this kit, so have the right ones on hand before you drain the coolant.

Install Notes

The hoses come preformed with the factory bends, so they go on where the old ones were. Seat each hose fully on its fitting, with no twist and no sideways pull on the radiator necks. If you're installing an aftermarket radiator at the same time, check its neck positions and sizes against stock before you assume the factory-shape hoses will line up. Check clearance around the bends, then refill and bleed the system using Honda's procedure for your year. Air trapped in an S2000's cooling system can cause hot spots, so take your time bleeding it.

What's in the Box

• Formed upper radiator hose, black (1)
• Formed lower radiator hose, black (1)
• Heater hoses, smaller coolant hoses, and clamps are not included

Mishimoto backs the kit with a lifetime limited warranty for the original purchaser when you buy from Mishimoto or an authorized dealer. Keep your receipt.

Fitment

• 2000-2003 Honda S2000, 2.0L (AP1)
• 2004-2009 Honda S2000, 2.2L (AP1/AP2)
• 2008-2009 Honda S2000 CR, 2.2L
• Fits the factory radiator hose route and connections. Check before ordering if your car has a relocated radiator or modified coolant plumbing
• Mishimoto part number: MMHOSE-S2K-00BK