ReedDerek

Sometimes the car will start to overheat a little. Reach the middle and maybe 1 bar over it on the temp gauge, but will go down if i drive normal. When i turn the heater on, it blows cold. The electronic part of the heater is fine as in the heater core part near the battery is opening and closing fine.

It seems it happens after I get into boost. We changed the themostat and bleed the system but it could be a bad themostat or not a good bleed. Maybe the mishimoto radiator is causing it.

My guess would be to change the themostat one more time and bleed the system the best i can and put the factory radiator back in. Worst comes to worst, change the headgasket.

Oil looks fine with no milky substance and car doesn't smoke.

Car info.

2005 s2000
Comptech supercharger kit / after cooler
81,000 miles
usual bolt ons
no check engine lights.

zeroptzero

There are a few posts on this issue with new rads being installed such as Mishimoto and Koyo. Cold heater air is almost always air in the system, keep bleeding it. What procedure are you following to bleed the system ?, try to describe it because the procedure is crucial. Hold off on the thermostat and rad change, just keep bleeding it. There's a post on this forum below with 6 pages of related info on this very issue, air in the system and bad rad caps seem to be the common issue.

AlX Boi

This sounds like the exact issue: https://www.s2ki.com/forums/index.php?showtopic=666773.

It seems to be a common issue with people who've installed aftermarket radiators.

zeroptzero

I just installed a Mishimoto rad and new Samco hoses, but my car is in winter storage so I have not been able to drive it. I've bled it twice and I get hot air from my heater, and no more air out of the bleeders. It appears that all of the air is out of it, but I won't know if it works properly until I can pusth it a bit on the road, same thing with the rad cap.