My reply was for a stock radiator not the Koyo, but I still stand by the coolant and Billman method.

 

Something os seriously wrong if you ever have to top off coolant ever.

Either you have a leak, or air was never fully purged.

Note that silicone hoses leak, as in they are porous and allow coolant to evaporate. Definitely not good to run silicone hoses on a street car (on track use only car, their higher temp range in more durable construction have benefits. While losing coolant and coolant smell aren't a big deal. You're topping up fluids before every session anyway.

So if you have silicone hoses, that's your problem.

Otherwise, find leak or purge air.

Once things are proper, you should literally never need to top off coolant before its 10 years or 100k miles and time to replace coolant again.

 

I have 3 silicon hoses around the intake manifold which is where I lose 100ml of coolant every 6 mo.

 

Rather than type much of this all over again... (Search function works!)

-- Chuck

 

I have been using Koyorad OEM copy radiator with great success.

This is NOT the big aluminum racing radiator. The Koyorad-OEM-Copy has plastic tanks and is an identical carbon copy of the OEM. Highly recommended.

Uses the OEM cap.

 

https://www.sakebombgarage.com/mr-si..._JjTPWRPUQngFn

Best radiator. No problems running full 10/10ths on track 5x 30minute sessions in 110F ambient in the middle of July.

 

This is what i ordered. Should I cancel the order or adapt? I got the cap that matches it? What is the capacity and bleep procedure for this radiator?

Koyo High Performance Radiator, S2000 - 2000-09 enpp-1051 $379.25

• Ordered1

$379.25 Sankei Coolant Expansion Reservoir Pressure Cap, 1.1 BAR - NSX, 1991-05 & S2000, 2000-09 enpp-3451 $17.50

• Ordered1

$17.50

How much coolant will I need for this model radiator? I am going from an OEM stock to this.

 

what you bought is fine. get two gallons of coolant from the honda parts department. You will probably only use a gallon and maybe a half.

 

That Koyo rad is too good, in cold weather your thermostat might not even open.

 

While you're replacing the radiator splurge on Honda "Long Life Antifreeze/Coolant Type 2." Service manual specifies replacing it at 120,000 miles or 10 years (long past!) and then every 60,000 miles or 5 years. I doubt the antifreeze acts like milk and spoils after a period of time but since most of us bought our cars used and may have never changed the coolant now is a good time even if your use is like mine averaging maybe 3,000 miles/year or less.

-- Chuck