Some basic cooling questions

I changed out the aluminum cooling tubes today because they were getting worn through.

I drained the coolant by simply disconnecting the silicone hoses. I then pulled a vacuum on the system down to 25mm and refilled the system with some water wetter solution.

The car at idle in my 90 plus degree shop is getting up to 237 degrees (!!!!) and the coolant overflow tube spewed out.

I'm wondering if
1) I didn't get all of the original coolant out
2) I've got huge air pockets

I could use some basic instruction on how you drain the coolant and refill.

Personally, I always leave the rad cap off after refilling, then start motor and burp the system adding water as needed. Once full, I watch for the water level to just start rising as it gets hot, then put cap on. A little more difficult if you have a tstat but I do it the same.

Thanks.
I think I am going to drain the system again at the left side return pipe and maybe crank the engine for a bit to pump out the residual coolant. Then I'll do another vacuum check for leak and refill.
I'll let it warm up with the cap off as you said.

If you let the engine warm up on a hot day when there is no driving to cool the radiators, is it normal to see temps as high as the 230s at idle?

I think that is high and not normal. Also depends how long at idle.

I redrained the coolant and went extra tight on all the fittings. I also found that the clamp on my radiator overflow line had a small leak so that despite plugging the line, it was leaking during vacuum application.

The car did NOT crank up to more than 190 idling and I did an infrared temp check on all the coolant lines which showed coolant was flowing normally.

Thanks for the help.

After that first run-up with the cap off, let it cool down and top it off. Repeat. Also try tilting the car. I always had to go thru the burping routine with my 1993 RX7 a few times. to get all the nooks and crannies resolved.

Remember, there is no fan. YES it will climb over 230 just sitting. I did it on grid one time when they neglected to tell us there was a red flag. It will heat until it explodes. ;0)

But yes, I like the "burping" the system stuff above.