I have a recently rebuilt small block 360. The coolant temperature was topping off around 205/210 degrees while driving it normal to hard in 80 degree weather. I drained and changed the antifreeze to a 50/50 mixture and added a pint of water wetter and let it idle (on another 80 degree day) for about 20 minutes and the coolant temperature stayed between 195/200 degrees at constant idle. My question is this. what is the normal/average coolant temperature while running on a hot day and at what temperature do you get into the danger zone of doing some engine damage?

Click to expand...