okay, how was I able to drive around for 2 days without my rad cap?

[dion]

I was working on the truck on Sunday checking fluids and such and today when I pulled into my driveway I saw my radiator cap laying there, never even came close to overheating, city and freeway driving. I was amazed but somebody out there probably has a story of when they drove around for a year without one

and no, I'm not an idiot!

I don't understand why it didn't get hot, especially the way I drive.

[67'ShortMonster]

Your coolant will still flow without a rad cap. It's just that the cooling system will not cool as well without the pressure. That's why when you blow a small hole in your rad... Undo the rad cap... Sometimes you get a lot farther without the pressure there.

[Longhorn Man]

The pressure raises the boiling point. If your engine was not heating it up to X degrees, (what does 50/50 boil at...is it 275?) then the pressure was not neded.
Straight water boils at 212 if not mistaken, and I know I start to panic if the guage gets over the 200 degree tick myself.

[dion]

thanks guys, learn something new everyday. I was always told you needed the pressure.

[dinnut]

reallly? thatts aweeesooommm!

[Longhorn Man]

You only need the pressure if the heat is high enough...or if you are going through Denver.
I had a rad that was literally falling apart and had to make a trip from Tx to Ky. I just pulled the little finger up on the cap, (I always get the finger type) and drove it 1000 miles there, 1200 miles while in Ky for a month, and then 1000 miles home. No problems at all.

[Fred T]

Chevy trucks didn't use a pressurized cap until 1952, when they started using a 4 lb. cap.