Hey all,

I'll be replacing the stock radiator on my 2007 with 175k soon with a Koyo radiator and I've got a couple of questions for the collective...
Car is tracked at HPDE events 5-6 times a year, otherwise a weekend car.

1) I realize I'll need a new rad cap and the Koyo is high quality but 1.3Bar vs 1.1 OEM. The stock Miata cap also fits the Koyo and is at 1.1Bar pressure like OEM. I realize that the higher pressure cap helps keep the system from boiling over at the expense of increasing the pressure of the entire cooling system, but the intent of the Koyo radiator is so that I don't have boil over problems, so I'm leaning towards the Miata cap. Any thoughts?
2) The radiator hoses are all stock with 185k miles and 17 years on them. I've had to replace a number of other rubber components like the air box tubing, cracked plastic wire loom covers, etc. Should I plan to replace the radiator hoses while I'm there? If so, I'd just go back with OEM and not High Pressure Silicone as I don't care about the aesthetic and don't see any real advantage of silicone vs OE.
3) I've read of people replacing the temperature sensor on the radiator...is that something that is prone to failure?
4) Anything else I should be considering while the system is torn apart (flushing, other ancillary equipment, etc)?

I plan to use the lisle fill funnel to bleed the system with appropriate Honda coolant.

Thanks!

 

The Koyo rad has way more capacity than the OEM system, you can use the 1.1 bar cap no problem since you'll likely never get the coolant hot enough to warrant the higher pressure cap. If you're going to replace the hoses, replace the thermostat as well, might as well only suffer the pain once. Otherwise, the stock hoses are fantastic and will go the distance as long as you keep motor oil off them.

 

I will chime in that knowledgable S2000 mechanics have said the hoses do not have to be replaced unless they are compromised by oil or hydraulic/brake fluid.

 

To add, silicone hoses allow coolant evaporation. Coolant odor under hood, and sometimes in cabin. Plus regular topping off. Risk of overheating (motor destroyed) if you don't stay on top of.

Silicone more heat resistant, good for track car, where regular topping off isn't inconvenience. Not so great for street car.

 

Hose clamp bottom it will have rotted

 

if you're draining the coolant anyways, check under the intake manifold for leaks at the small hoses or the o-rings.

 

Thanks all!

Sounds like sticking with the stock hoses is good! I’ll grab a lower hose clamp just in case.

No must have upgrades it sounds like while I’m working on it.

@spider2k I’m totally down for looking but not sure exactly where you mean?

 

I might add to re-use the OEM hose clamps. They work great forever. Better than any replacement.

 

I painted end tanks black, to look more like stock.

I also added some foam insulation to sides, to prevent air from going arou d radiator. Its all forced through. Its held up perfectly.

Foam used was a home depot window ac foam kit.oddly fit perfect.

koyo black and foam insulation added

 

@cosmomiller for sure! I’ll definitely go with OEM replacement clamp for the bottom hose. It’ll be good to have the same wear pattern as the original too.

@Car Analogy ive actually saved your instructions because I’m planning to do the same exact thing! My car is nearly all stock, so keeping it OEM(ish) makes sense to me for now. I’m sure once I roll fenders, go with a square wheel setup, and rebuild / upgrade the engine I’ll be singing a different tune, but for now she rolls OE style