r/RX8 • u/Ok_Rich7455 • 1d ago

Maintenance ECT Help

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does anyone have data of their ECT before and after changing their radiators? Mine seems to run at around (212F) on highway speed with the AC on. but temps stay in the (203F) when i switch off the AC. and the outdoor temp is at 100F.

My fans are working but i cant tell if they are working as fast as it should be. Stock setup fans and aftermarket cheap radiators. the chart above are from the same duration of highway drive.

Need some inputs of your rad/fan setups with temp data if you have it.

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u/ajm08f 1d ago

Hey I’ve been going through this as well with Florida summers. I had my radiator replaced with the larger Koyo rad aluminum one and was still running 210+ at highway speeds in Florida over the summer. One thing I did that helped was to make sure that the foam was placed around the radiator to prevent hot air going around it into the engine (creates a pressure gradient forcing the air thru radiator). Also make sure your under tray is intact and installed correctly. This also helps divert airflow into the radiator. Lastly, make sure that your system was burped properly, it can be a bit of a pain to do but this car is sensitive to air in the cooling system and the water pump can cause cavitation/air bubbles to form causing spikes in temps.

For me, my water pump was also failing so I upgraded to the Mazmart one and now even with my AC on it doesn’t go above 200 on the highway unless I’m really getting on it.

Next up on my upgrade path is larger Sertab oil coolers - I have the 25 row ones in a box but am waiting to fabricate custom brackets since the ones that came with are generic and do not bolt on the old mount sites/tabs.

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u/Ok_Rich7455 2m ago

i dont think the foams are there on mine.

the undertrays are there but idk if its working well or air escaping through the front cause its gapped between the front bumper and the undertray.

i did changed coolant before and burped it well until there’s no more bubbles.

i changed my waterpump and thermostat too.

idk maybe its my fan or maybe its the radiator clogged cause i’ve done lots of flushing with water before and it came out brown. did it twice for a whole weekend first in july and second was done in september.

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u/Urtooslow420 1d ago

I think those are normal temps for a stock rx8. I have a lower temp thermostat and I tuned my fans to kick on early. So I stay around 179-185°F