430 Engine Losing Water

[mit634]

Hi All,
My 58 Mercury with 430 engine loses vast amounts of water. I always top it up before I drive it but when I get back I can't even see the water level in the radiator it's so low. I know it spills out the overflow. Funny thing is that it never runs hot - the temp gauge only approaches the 'N' mark and stays there. The radiator cap doesn't pressurise - I'm keeping it that way because there is a very slow water leak somewhere on the engine. Need to fix that before I can attempt to let it pressurise.
Just wondering if you guys had any thoughts on what might cause several liters of water to disappear out the overflow after even only a short trip.
Sorry I know my car isn't a Tbird but other forums aren't as helpful as this one.
Thanks
Tim

[simplyconnected]

Tim, water boils at sea level @ 212*F. Your cylinders get hotter than that.

For every pound (PSI) you pressurize your system, the boiling point goes up three degrees. That means if your radiator cap is set at 7-PSI, your boiling point went up 21*. So, 212 + 7 = 219*F. (It works just like a pressure cooker.)

That's why it is so important to run your radiator under pressure, to keep the boiling point high, so your coolant will be contained. You're shaking dice by allowing steam to spew your coolant. Water (by itself) has no water pump lubricant and it is less efficient than 50% anti freeze/coolant.

I hope you get your leak fixed soon. - Dave

[60 T-Bird]

Tim, water boils at sea level @ 212*F. Your cylinders get hotter than that.

For every pound (PSI) you pressurize your system, the boiling point goes up three degrees. That means if your radiator cap is set at 7-PSI, your boiling point went up 21*. So, 212 + 7 = 219*F. (It works just like a pressure cooker.)

That's why it is so important to run your radiator under pressure, to keep the boiling point high, so your coolant will be contained. You're shaking dice by allowing steam to spew your coolant. Water (by itself) has no water pump lubricant and it is less efficient than 50% anti freeze/coolant.

I hope you get your leak fixed soon. - Dave

Dave...don't you mean 212+21=233F...?

[simplyconnected]

Dave...don't you mean 212+21=233F...?

Yeah, I do. Must have been up late last night. Thanks.

[scumdog]

If you've a big enough cooling system you can run less pressure, i.e. my 429 '55 F100 only runs 4lb pressure and I have no overheating problems. (even when my top tank was split and I ran NO pressure!

But then I don't live in Arizona!!

So any pressure is a blessing when the temperatures got up to 212 degrees or more.

[vernz]

I was losing coolant every time I drove my 430 until I realized that I was filling the surge tank too high when I topped it off before every drive. You mentioned you top it off all the time. I read that the tank should be about 1/4 full.

Vern

[tbird430]

I would keep an eye on you engine's oil level & watch the exhaust pipes for excessive moisture (after full engine warm-up).

[mit634]

Hi everyone,
Thanks so much for the responses. Appreciate your time and thoughts. The 58 Mercury has no surge tank and so you just fill up the top of the radiator. After a long drive no water is visible in the top of the radiator anymore, although you can't see the top of the tubes because there is a sheetmetal plate blocking the view. It makes sense that I should fix any external leaks and let the system pressurise so that it is operating properly before I do anything else.
Thanks again !
Tim