Boiling point of anti freeze

[joshuajim]

I flushed and refilled my trucks radiator today. I noted on the bottle that a 50/50 solution of antifreeze/water will result in a 256 degree boiling point. This piqued my curiosity so I did a little research. In reality 50/50 antifreeze only raises the boiling point by 8 degrees. The 15# cap on the radiator is what gets you to 256.

[ROBERTSUNRUS]

joshuajim wrote:
I flushed and refilled my trucks radiator today. I noted on the bottle that a 50/50 solution of antifreeze/water will result in a 256 degree boiling point. This piqued my curiosity so I did a little research. In reality 50/50 antifreeze only raises the boiling point by 8 degrees. The 15# cap on the radiator is what gets you to 256.

🙂 Hi, this is how it works:

Water boils at 212 degrees.

A 15lb. pressure cap increases this to 3 degrees per pound. = 45 degrees.

Now you are up to 257 degrees.

With all of the above and a 50/50 mixture of coolant, you can add another 30 degrees. This gives you a grand total of 287 degrees before puking into the street.

This information was from a General Motors school while explaining that GM's idiot light comes on at 261 degrees. And if this vehicle only has water and a 15 lb. cap, (no coolant) it can boil over and the idiot light will never come on.

[rhagfo]

Better than 50/50 is 60/40 antifreeze/H2O, higher boiling point and lower freezing point.

[MEXICOWANDERER]

And there is nothing better than an original equipment brand radiator cap (and thermostat). My Kubota has 80% DOW anti-freeze plus Nalco cooling system treatment. The remaining 20% is distilled water hauled down from the states.

[marcsbigfoot20b]

RCMAN46 wrote:
At 10,000 feet that temperature drops to about 237 degrees f.

Do tell????

[theoldwizard1]

A lot of newer cars have higher pressure systems, 18-20 psi.

[Jframpey]

Good to know - I think I’ll get a new cap tomorrow. I’ve never changed mine, 10 yo truck!

[SidecarFlip]

Very good observation. Now for the fun part. Radiator caps as they age, tend to loose their ability to hold pressure in a cooling system. Caps should be replaced every couple years. Most people never do however. Mine goes in the trash every 2 years. That is especially important with a diesel motor as loss of pressurization of coolant can result in hot spots on the cylinder liners and big mechanical repairs.

All for a 6 buck part.

[RCMAN46]

At 10,000 feet that temperature drops to about 237 degrees f.

[coolmom42]

Yep, the pressurization is absolutely critical.

[MDKMDK]

Good to know. Especially when I'm watching my coolant temp underway.
Thanks.