Water Temperature

[shearhawk]

What is the normal water temperature range for a 454 Chevy Class A?  I have noticed here on the florida Interstate it will slowly climb to 210 degrees, and hold.  When I pull off it will slowly drop approximate 40 degrees.

Thanks,
Randy

 

[JIGGS]

I CAN ONLY TELL YOU ABOUT FORD ENGINES. MY FIRST MH WAS A CLASS C 27'460 ENGINE AND WATER WOULD RUN 210 AND I HAD NO PROBLEMS. THIS MH IS 37' 460 ENGINE AND IT WILL RUN 220 A LOT OF THE TIME. EVEN 225 WHEN GOING UP HILLS OR PULLING A TRAILER.  I HAVE ASKED MECHANICS ABOUT THIS TEMP. THEY ALL SAID IT IS NORMAL. LOT OF THE OLDER PICKUPS WITH THE BIG BLOCKS WOULD RUN WITH TEMP LIKE THESE

 

[John From Detroit]

Turns out that some engines run a bit cleaner at slightly, and I mean slightly, higher tempertures (IE 210)  Now, I understand that folks get a bit concerned when they see tempertures over 200 cause water boils at 212 right? Wrong as it turns out, water boils at 212 if it is pure and under exactly ONE ATMOSPHERE of pressure. now if your pressure cap is labeled 14 lbs, then that is almost exactly TWO atmosphers of pressure (14 lbs from air pressure and 14 more from the cap) I've seen higher pressure caps, higher pressure means higher boiling points.  Also "Anti Freeze" is also "Anti Boil" (There is an exception but I have not seen it in my lifetime) and will also raise the boiling point.

The only way to be sure what's normal is to ask the manafacturer.  I've seen 175 degree thermostats, 180, 190, and higher.  Without knowing what the designe operating range is, I can't say if 210 is normal or not.

Page 2: Dashboard temperture guages are not what I'd call a "Lab Standard"

(By the way, did you know water can boil at much lower tempertures if the pressure is less than one standard atmosphere)

 

[Rex]

The one I had for 4-years always ran that hot.  The engine book I had indicated that was the correct temp.  Never had any problem with it.  It would only warm up a bit when climbing long grades.

 

[Karl]

Shearhawk,

210 is nothing to worry about but, regardless of temperature, make sure your radiator is free of debris, your belts are not too worn and are tensioned properly, and the hoses are not too old or have bulges, and the clamps are tight. Most mfg's recommend changing the antifreeze every two years, and you shouldn't increase the concentration of antifreeze to water beyond what is recommended as this will actually decrease the boiling point of the coolant.

John:

water boils at 212 if it is pure and under exactly ONE ATMOSPHERE of pressure. now if your pressure cap is labeled 14 lbs, then that is almost exactly TWO atmosphers of pressure (14 lbs from air pressure and 14 more from the cap)

Not true. The engine/cooling system is a CLOSED system and is relatively unaffected by atmospheric pressure except for a very slight pressure exerted on the flexible rubber hoses. The system was designed to be closed so that it could perform equally well at sea level or at altitudes where water would boil at relatively low temperatures. The spring in the radiator cap maintains an artificial 'sea level atmospheric pressure' regardless of altitude.

 

[John From Detroit]

Karl wrote :
'Not true. The engine/cooling system is a CLOSED system and is relatively unaffected by atmospheric pressure .....
'

A common mistake Karl is thinking that zero on a pressure guage is truly zero, it's not, it's one atmosphere. or about 14psi (I stress about)

Though the fairly minor (in terms of psi) flucuations in atmospheric pressure won't make much difference in the boiling point of water (Few degrees) if you remove the pressure of the air against the radiator cap's releif valve then the ONLY pressure acting on the water would be the cap, in the case of a 14lb cap that would leave you with the equivlent of an open container.

Think about it 14 lb cap, plus 14 psi air pressure means 28psi total,  The radiator only needs to contain 14 though

About the only time this is important is in calculating the boiling point of water (For our purposes at least) and in a few other design areas which we don't much worry about lessen we work for NASA or JPL

Normally we worry only about pressure differences.  Which is what the radiator cap controls and a guage measures the boiling point of water under pressure is the exception

 

[shearhawk]

Thanks, for the input.  Seems a little scary above 200, specialy when the temperature guage max's at 260.

Thanks,
Randy

 

[Karl]

John,

Just to set the record straight, every physics and chemistry calculation is assumed to be at "standard presure" and "standard temperature" unless otherwise stated.

Standard temperature is defined as zero degrees Celsius (0 0C), which translates to 32 degrees Fahrenheit (32 0F) or 273.15 degrees kelvin (273.15 0K). This is essentially the freezing point of pure water at sea level, in air at standard pressure.

Standard pressure supports 760 millimeters in a mercurial barometer (760 mmHg). This is about 29.921 inches of mercury, and represents approximately 14.7 pounds per inch (14.7 lb/in2). Imagine a column of air measuring one inch square, extending straight up into space beyond the atmosphere. The air in such a column would weigh about 14.7 pounds. This is measured from sea level, which is more or less the same throughout the world (ignoring tides, major storms, etc.)

Here is a brief table of boiling point vs. altitude:
0' - 212
2k' - 208.4
4k' - 204.8
6k' - 201.1
8k' - 197.4
10k' - 193.6
12k' - 189.8

Though the fairly minor (in terms of psi) flucuations in atmospheric pressure won't make much difference in the boiling point of water (Few degrees) if you remove the pressure of the air against the radiator cap's releif valve then the ONLY pressure acting on the water would be the cap, in the case of a 14lb cap that would leave you with the equivlent of an open container.

As you can clearly see from the above examples, altitude makes a significant difference on the boiling point, and are taken directly from the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. 1997. ASHRAE Handbook - Fundamentals, Inch-Pound Edition. ASHRAE. Atlanta, GA. and can be calculated using the following formulae:
pressure (in. Hg) = 29.921* (1-6.8753*0.000001 * altitude, ft.)^5.2559
boiling point = 49.161 * Ln (in. Hg) + 44.932

I would be happy to explain them to you, if necesary.

 

[Gary RV_Wizard]

ust to set the record straight, every physics and chemistry calculation is assumed to be at "standard presure" and "standard temperature" unless otherwise stated.

Pressure gauges measure the difference in pressure from some base point.    For common air and liquid pressure gauges it is  the ambient air pressure that is the base. In the case of a radiator cap, we are talking about a relief valve that opens when the pressure differential exceeds some value. For a 14 psi cap, I believe that is 14 psi above atmospheric.  As Karl has shown, altitude and hence air pressure does have a significant effect on the boiling point and a radiator under an additional 14 psi of pressure will not boil until about 260 degrees at sea level.  But if the vehcile travels to a mountain top where ambient pressure is substntially reduced, the relief overflow opens at a lower absolute pressure (14 psi above a reduced ambient air pressure) and thus still "boils" at a somewhat lower temperature than at sea level.  It is sometimes necessary to use a higher pressure radiator cap in vehicles that are frequently operated at veryhigh altitudes.

Bottom line for Randy is that 210 is well within normal operating parameters for a modern engine.  Modern engines run at these high temperatures because fuel burn efficiency is improved and emissions are reduced.  What seems a bit unusual in his case is that the temperature fluctuates well below the desired 210.  It is more normal for the cooling system thermostat to remain partially closed until the temperature reaches the desired point and then open/close as needed to maintain that point. Wonder if his thermostat is functioning properly?

 

[John From Detroit]

John,

Just to set the record straight, every physics and chemistry calculation is assumed to be at "standard presure" and "standard temperature" unless otherwise stated.

Now we are on the same page Karl,  As I said, when you figure the effect of increased pressure on water you have to figure the "Standard Pressure" (one atmosphere) as a starting point, and then you add in the additional pressure caused by the radiator cap, but the starting point (reference point in you like) is one atmosphere (Standard Pressure) or, in very round figured 14psi, which is why I used a 14psi cap (makes the math easier)

By the way, thanks for the altitude v/s boling point chart, very useful in some cases

Normally, you reference all pressures to "Standard" (that is zero is normal air pressure) this is one of the exceptions where you have to include "Standard" in the calculation.  it is the ratio of ABSOLUTE pressures that controls the boiling point, though if you wish to prepare a chart (In fact, I'm going to ask since it seems you have the math handier than I) you can reference to standard, by simply subtracting it at the proper point (or adding it as part of the equasion)

I would not mind seeing a chart that shows something like

Pressure cap 12, 14, 16, 18, 20,  Normal boiling point at sea level xxx yyy zzz www