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what color are your radiator tanks. Are they dark black or black with a slight coolant color (orange or green)? If slightly colored, or not sure, look at the tanks with a magnifying glass. The plastic tanks will fracture with a fine mesh of cracks when old. they will seep coolant very slowly, it will likely never hit the ground, but the water will evaporate. you will smell it when it evaporates. I had this problem once, never found the leak but kept slowing adding water.
You can also get a UV dye to put in the water the look for the leak with a UV flashlight. Done that too. If you get pretty glowing exhaust pipes, pretty much says seal leak.
I added this to my cooling system from Pettit Racing to get rid of any trapped air. Might be overkill, but it seems to be working fine. I also added other cooling mods, like new aluminum Koyo rad, lower temp fan switch kit, lower temp thermostat, better water pump, and oil cooler lower temp thermostats, plus all new silicone hoses from Racing Beat. Together everything is running lower temps (read on OBD2 reader) for my move to Texas and its summer heat. Drove my RX8 straight from New Jersey the 1500 miles to Grapevine, Texas (near Dallas), Driving for stretches of ten hours straight with air temps over 90-95 degrees and at high speeds, and the coolant temp stayed between 190-195 degrees. Nice.
Last edited by gwilliams6; 06-14-2018 at 08:26 AM.
Hello all. Just wanted to write back with an update and for some closure after exhausting all possibilities for the over temp issue I was experiencing.
Finally completed the engine rebuild as I planned on doing (even before the temp problem). Had a few hiccups after the first engine reinstall due to a minor discrepancy with the side seals sent by Atkins Rotary. They were a bit too small and would stick down into the rotor and lose compression. Just a heads up to all who are thinking about buying a kit from them. A friend of my mechanic in New Zeland had the same problem with the same kit. All good now tho. Used my old seals, which were in perfect condition.
Anyway as soon as the rotor housings were removed for the first time, the cooling problem was apparent. Not only was my water jacket seal compromised in several areas, but the cooling channels around the housings were heavily corroded and blocked by what appeared to be sand! and mystery ‘gunk’. Not sure how any of it got in there in the first place.
But we’re good now. Up and rolling. Had the engine street ported as well so she’s a bit more perky and coolant is actually flowing this time.
Side note; I had overheated several times during this issue and I just want to say that the interior parts of my engine were/are in perfect condition. So for those who say that ‘as soon as the temp needle moves, you’re screwed’ I’m going to have to respectfully disagree. Just don’t be an ***. Is it overheats just stop and let it cool off. It’ll save you some worries later.
HUGE thanks to all who contributed to this thread and took the time to write me with theories/ideas, I learned a whole lot and was even able to help others with some of their problems, and will still use some of those ideas to assist with cooling even though the problem is solved.
Thanks again from Barbados’ small but growing rotary scene!!
Douglas S. Thought I'd give it a try. You can see the corrosion and blockage causing low coolant flow.
That goo looks like what happens when folks use Water Wetter or similar coolant additives. Or if its really corrosion, perhaps someone ran straight water without anti-corrosion agents, and then water wetter.
Anyway, glad you fixed it. Be real careful what you coolant you use. Stock Mazda FL22 is fine for most applications.
06-13-2018, 09:23 PM
