Since I installed by Koyo, the car seems to get hotter after shut off than it did with the stock unit. It runs cooler during operation but after shutdown seems to get hotter in 5-10 minutes than it used too. I always run a nice cooldown and frequently run the fans during the cooldown. If its under 90C when I start to "warm down" it will actually warm up to 89-90 C during the warmdown. If it's 95 or hotter at start of warmdown, it will cool to 90 (93 unless I run the fans). Outside temps around here are running low to high 70's.

Anybody else seeing this? What is the cause? How is it fixed?

 

I just installed the koyo and my car runs warmer now. But I also put a larger front mount on at the same time as installing the radiator. So I guess thats why It runs hotter. After shut off Ive never noticed the temp rise, though I usually keep the fans running at shut down. I will shut it down with fans off and watch the gauge and see if it rises. I will let you know

 

Are you using the same temp scale here, I am assuming the outside temp you are referring to (70's) is in deg F.
I am also assuming you have a water temp gauge from your post. It is normal for the water temp to rise a little after the engine is shut off, since the thermostat will remain open until the coolant reaches the closing temp. This should be the case with the stock radiator as well.
The thermostat will remain open until the coolant temp is under 98.8 deg C or 210 deg F (unless you have the 180 deg F thermostat). When the car is stopped and shut off, the radiator is not as effective and the fan you are referring to is probably at low speed. So under these conditions the coolant temp will actually rise to slightly above the thermostat opening temp.

 

If you are really worried run a switch to your fans and let them run on high for a couple of minutes after you shut your car off, just don't forget to turn them off. You can run a wire from the fan diagnostic port to the a switch and then to ground this will turn the fans on in high. If you want more info let me know. There is also some sort of fan mod you can do with the ecu that lets the fans run for a couple of minutes after shut down.

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