Was it running hot before the new rad?

 

Have you put some foam around the new radiator?

 

What are you meaning by foam? Like to stop it from rubbing holes in the radiator?
I installed my radiator and never used any foam and mine works fine

 

 

 

The OEM radiator has some foam pads around it so the air can't go around the radiator and instead will be forced through the radiator.

 

After the car is running for a little while feel the top and the bottom radiator hose's and see if one is really hot and the other one is kinda cold, this could mean that it's not moving fluid. If they are about the same temp then it will be pumping the coolant. Does the car over heat sitting still?

 

 

 

 

I used the biggest pipe insulator foam I could find on the shelf at Home Depot. I want to say it was for 1" pipe.
I cut it in half lengthwise to give me a flatter mating surface and used 3M Super 90 spray glue to attach it to the left side (when facing direction of forward travel) and bottom. Haven't seen the need to foam the top yet.

You'll need to cut two segments for use on the left side since there's something that gets in the way (can't remember what it was, oil cooler line maybe?). I doubled up the halves of the foam to make sure it was thick enough to fill the gaps.

For the bottom, I also ran zip ties through the existing aero holes in the undertray and around the lower radiator brackets. This helps keep the undertray sealed to the bottom radiator foam. This may not be necessary if you aren't missing fasteners and your undertray plastics aren't warped from repeated exposure to motor oil. Depending on your radiator and how you cut the lengths, you may need to cut a hole in the foam to access the radiator drain plug.

I didn't foam the right side to allow airflow around/through the hottest part of the engine bay (around the exhaust manifold).

The only prep work I did on the radiator was to wipe it off with some windex but my radiator was brand new out of the box. You may want to be more thorough with your cleaning, possibly even give it a once over with some sandpaper to rough it up and give the glue something to sink its teeth into. If you use the same spray glue I did, another key to a good bond is to read the directions carefully. Spray both surfaces and let them sit for about 5 minutes before bonding.

With this setup, my cruising temperatures rarely go over 185°F in the summer and hover around 176°F (tstat opening temp) in the winter. On the track, my temps stay below 215°F and quickly drop to around 185-190°F by half-way through the cool down lap. That's with a stock tstat, stock water pump, and CSF 3164 radiator.

 

These cars run hot, all you can do remove obvious weaknesses in the system so that it can work as best as possible and avoid an overheat condition. You've already uprated the radiator, adding foam will help assure all the air flow goes through the radiator instead of bypassing it. Also make sure your undertray isn't sagging, you can use zip ties to pull it closer to the sub-frame if it is. There is a guy on eBay selling aluminum undertrays that won't sag, giving better fitment to the radiator. The stock water pump is fine except for sustained high-RPM use, a REMEDY waterpump will help there, but isn't worth it if the car isn't seeing extended high-RPM operation. Hood vents help too but they are often kind a chintzy/tacky -- I still haven't found an aftermarket hood I like the look of for the RX-8. Lower TSTAT's don't improve cooling that much, especially since ours opens at 184* from the factory. The fans come on later than I'd like from the factory, and their hysteresis setting is too narrow so they don't run as long as I'd prefer. The relay mods help but the best fan control solution is to calibrate the ECU with Veratune/MazdaEdit/Cobb so that they cycle on earlier and stay on longer.

I went with the black EPDM/rubber pipe insulation from Home Depot, it was the smaller of two options, I believe for 1/2" piping. I was able to work the foam underneath the condenser hardlines so that it was tightly fitted into the space; the curvature of the rubber insulation helped it cup the radiator, springing itself against the other surfaces to improve sealing. I didn't have any 3M Super Adhesive as I'm in the middle of a house move, but the foam was thick enough that it wedged in nicely between the sections of unibody, undertray, and radiator. I may go back and rivet/glue it during my next oil change.

 

 

the ac could be the circuit board needs fixing look for the DIY. and 220f is where damage can start occurring

have you read the new owners thread yet?, no really read this!

 

I get nervous after 220 and aim to never exceed 230. I get a hot oil smell too, suspect it's oil cooking on the engine from 14 years of oil fills, top-ups, etc. Also I had a leak at the OMP for a while, which sprays oil on EVERYTHING and manifests only at high rpm, so check that.

As for the A/C toggling back and forth... while the compressor operates, it's cold, while it doesn't operate, I imagine it's warm. The compressor doesn't run full-time. Normally the temperature averages out, but suppose if you had lost refrigerant or some other A/C problem, things could get hot. And the condenser is right in front of the rad, so if that's hot, it's heating up your radiator.

 

The whole point of the A/C system is to take heat from the evaporator in your dash and dump it at the condenser in front of the radiator. If the A/C compressor is running, the condenser should be hot.
This is why I disagree with people who run the A/C to try to cool the car down; you're just increasing the temperature of the air that is passing through the radiator.

 

OP, it sounds from your first post that the car heats up even when A/C is off, so..
- you didn't answer if it ran as hot before the new rad?
​​​​when did the issue first manifest?
- are you sure the cooling system is pressurizing properly? Perhaps get it pressure tested. Could be a weak rad cap or there is a coolant seal problem in the engine. Caps are $5 and a test will confirm/negate the rest.
-what rpm/gear/speed are you maintaining when the issue occurs? Does it cool back down if you slow down or speed up?