Yes to the car over heats, or yes to the fans come on and shut off? If you idle the car with AC off with the hood open, does the driver side fan eventually turn on and then back off? If so what does the temp gauge look like during this?

How many times did you let the fans turn on and off while burping with the funnel? I generally let it go 3 times before I consider it good and then top off and put the cap on.

I think your thermostat is sticking personally.

Its more likely than you think.

It overheats, yes the fans come on and shut off. Not sure on the driver-side fan coming on and off, it may not with the Enhanced MS2. The factory temp gauge never moves but it has clearly boiled over.

I usually cycle it once with the nose in the air if there are no bubbles poping.

I'm going to pressure test again tomorrow to check for leaks.
The old one checked out in a boiling pot, put it back in, then replaced with a new one that checked out. I considered shooting the waterneck to make myself feel better.

Is the stat installed the right way?

It's a pain in the ass, but try running sans stat and see if it still overheats.

You also may have a blockage somewhere in the cooling system causing your issue. Does the coolant look nasty?

Coolant looks crystal clear after flushing. thermostat is installed correctly.

The car should not overheat while idling with the AC on. Either insufficient coolant flow through the radiator, or insufficient fan airflow through the radiator, or crud built up in radiator acting as insulation. Doublecheck that both fans are indeed coming on and that neither is spinning backwards.

Confirmed, both come on and spin the correct direction. I'm guessing the water pump is weak, but I don't know how this is possible.

Or, I have a bad calibration on the sensor and 3 bad radiator caps. 1 is old, one is from China, and the other is from the green car.

So what are the chances your radiator has gone to crap?

Edit: if the thermostat is fine, and coolant is flowing, and the fans are coming on, and you used the Magic Funnel of No-Air-Pocketness, and the fans are actually pulling measurable airflow through the mouth of the car, then seems to me there's lousy heat transfer through the radiator itself. We're about out of variables. Can water pumps go bad other than failing at the bearing and leaking?

The radiator is like 3 weeks old.

hg failure? how hard are the hoses when it is hot?

It does - first fan comes on at 203*F, second fan comes on at 208*F.

I've seen plastic impeller water pumps fail, the blades basically disintegrate and can't pump the fluid enough to properly circulate.

I was re-reading through this post and noticed that you mentioned 110F ambient temps. That's pretty f'in hot.

How are you testing for leaks? My pressure tester goes in place of the rad cap. Then I pump it up till the little gauge says whatever pressure I want to test at and I wait for it to leak down or not. When my HG was leaking, it lost 1 psi over about 2 minutes. It was a very slow leak. Slow enough that I wasn't sure if it was just my fancy all-plastic radiator tester or not. But it was very repeatable.

Got an IR temperature probe? You might remove the fans temporarily and point that probe at the back of your radiator. See if there's any cold spots. It might be a pain since you taped on the fans, but at least you'd be certain the rad was working correctly.

I am not convinced that the stock cooling system can cope with 109*F and A/C.

If everything is perfect, the stock system can keep up, but there's always other issues which will easily take the system past its heat transfer limit. It's already close to the limit due to an inherently bad design. There's no reason not to run a reroute and have more even cylinder temps, and a lower average temp.

As the flow around a cylinder decreases, the deltaT between the cylinder wall and the surrounding coolant decreases, leading to less heat transfer. This can overload the system as it increases in local temps raising average temps. It also later crops up in more serious problems like causing headgasket failure, which is usually later blamed for the original overheating issue.

Most cars don't need reroutes, but all of our cars would benefit from a reroute. Our local heat and humidity can stress a car nearly as much in traffic as FI or track use, and a reroute has been the best solution in my experience.

It did last year and I sat in traffic with 112*f heat.

My water pump is all metal btw.

I'm pressure testing by charging through the rad cap neck. lol

Mine couldn't keep up with A/C with temps in the 110-115 range. The radiator was installed by the previous owner, and appeared somewhat new-ish (I'd guess replaced within the past 1-2 years). I tried sealing the fans to the radiator, water wetter, 80/20 water/coolant ratio, setup ducting so 100% of the airflow went through the condensor + radiator, and it still would creep up to 235+ if I had the A/C on driving 70 mph on the freeway. Turning off the A/C would bring it back down to ~210.
I replaced the radiator with a Mishimoto, and it holds at 210-214 under the same conditions in 110-115 degree ambient temps with the A/C running full blast..

He has a CXRacing radiator which I'm assuming is a thicker all metal unit.

Was there any signs of somone using a stop leak product in the past?

Have you taken the water pump off of this car? I have seen the prop wear the block and or housing enough to let water flow around the pump so to speak. Ya might take a listen to the pump while running to maybe hear a milling machine.

I can't hear anything with my stylish det-cans clipped on to that area. I ran acid through the cooling system to clean it out, hopefully this did the job.

I jacked the nose of the car way up in the air with magical funnel of ultimate success and no air came out. The car idled up, one fan came on and never turned off. Number 2 came on then both turned off. With the AC, it boils over the cap. The cap looks great and physically feels stiffer than the old one. I'm perplexed. I'm guessing a water-pump problem. I need to squeak by until September when I take a week off from work to do the swap and tune the car. I'd do the swap now, but not in this heat.