Radiator cap pressure question?

[Mark B.]

Re: Radiator cap pressure question?

Oh, also, Coolant (glycol) in aircraft engines cooling systems was not used to increase cooling, but to stop freezing.

[Duke W.]

Re: Radiator cap pressure question?

Modern antifreeze is not "coolant", and is a crappy heat transfer material and only serves to prevent freezing and lubricate the water pump marginally.
The higher pressure cap is a band-aid solution to allow "antifreeze" mixtures (50/50 or otherwise) to try to transfer heat as good as water.
It's arguable that at high altitudes a higher pressure cap would allow any given cooling liquid to reach the same temp before boiling as an engine at a lower altitude with a lesser cap.

Pure (de-mineralized) water is still the absolute best heat transfer liquid. The lowest pressure cap you can run and not overheat is the best pressure cap.
The best "coolant mix" would be the de mineralized water, an adhesion promoter, a water pump lubricant and a corrosion resistor.
"Water wetter" (a glycerin product the promotes water adhesion, and contains a water pump lubricant, and corrosion resistor) is a product I use.
Many people who race cars will be familiar with "water wetter" or "30 below" or other non-antifreeze products and water combos as antifreeze is normally forbidden at the track..

The most important function of antifreeze beyond engine cooling is corrosion protection. It's not important for a racing engine since they are not expected to be in service for decades, but you better be aware if you own a vintage car, and aluminum is particularly unforgiving of insufficient corrosion protection. Water Wetter does not provide corrosion protection or service life equal to modern antifreeze products.

For a vintage Corvette you need an antifreeze product that protects iron, aluminum, and copper/solder, and the best is an HOAT type like Zerex G-05. Some modern OAT blends (like Dexcool) do not provide good protection for copper/solder because many cars have not had copper radiators or heater cores for at least a couple of decades.

Duke

[Mark B.]

Re: Radiator cap pressure question?

Hi Duke,
I have seen your very knowledgable posts, and enjoy reading them. You are a much appreciated provider of intelligent information in this forum.

Yes, I agree 100% corrosion resistance is extremely important in vintage automobiles. Vintage car enthusiasts should be informed and make the right choices when protecting scarce and very valuable engine components.

Surprisingly most corrosion is caused by an acidic antifreeze solution that has been left in the system too long, or electrolysis from poor engine grounding, or regular tap water in the mix, or a combination of all of the above.

Also, the key is the use of demineralized water in a clean system. It does not corrode nearly as much as you would think as it is not a good electrical conductor.

Water wetter contains a good corrosion inhibitor, and used in it's listed concentration will provide ample corrosion resistance.

I change my coolant every year, and have zero corrosion problems. I am running a 55 rad in my 57 with its original core, still working perfectly, no leaks or damp spots.

After saying all that, for most people it probably is "easier" to just do the regular antifreeze thing as most people do. As long as you don't use tap water in any way shape or form with or without antifreeze. Also people tend to be lazy and forget to put antifreeze in their car in the winter, and we all know what happens then. If you live in a warm climate year round, there is no reason to use antifreeze in my opinion.

More importantly, all I wanted to clear up were the common misconception about antifreeze being a coolant , or providing better cooling (it's not and doesn't) and the actual reason for higher pressure caps since the fellow who started the thread was under the impression that a higher pressure cap is better because it provides more or better cooling. His engine will run at the same temp it always does regardless of the cap choice.

Side note, adding water wetter or 30 below to your radiator fluid, (whatever the mixture or choice) will provide more efficient cooling solely by the benefits of the adhesion promotors which is the most important aspect of those products other than lubricants and corrosion resistors.


Sorry for the long posts, and no, I don't work for Red Line oils (water wetter) lol......

[Joe L.]

Re: Radiator cap pressure question?

Hi Duke,
I have seen your very knowledgable posts, and enjoy reading them. You are a much appreciated provider of intelligent information in this forum.

Yes, I agree 100% corrosion resistance is extremely important in vintage automobiles. Vintage car enthusiasts should be informed and make the right choices when protecting scarce and very valuable engine components.

Surprisingly most corrosion is caused by an acidic antifreeze solution that has been left in the system too long, or electrolysis from poor engine grounding, or regular tap water in the mix, or a combination of all of the above.

Also, the key is the use of demineralized water in a clean system. It does not corrode nearly as much as you would think as it is not a good electrical conductor.

Water wetter contains a good corrosion inhibitor, and used in it's listed concentration will provide ample corrosion resistance.

I change my coolant every year, and have zero corrosion problems. I am running a 55 rad in my 57 with its original core, still working perfectly, no leaks or damp spots.

After saying all that, for most people it probably is "easier" to just do the regular antifreeze thing as most people do. As long as you don't use tap water in any way shape or form with or without antifreeze. Also people tend to be lazy and forget to put antifreeze in their car in the winter, and we all know what happens then. If you live in a warm climate year round, there is no reason to use antifreeze in my opinion.

More importantly, all I wanted to clear up were the common misconception about antifreeze being a coolant , or providing better cooling (it's not and doesn't) and the actual reason for higher pressure caps since the fellow who started the thread was under the impression that a higher pressure cap is better because it provides more or better cooling. His engine will run at the same temp it always does regardless of the cap choice.

Side note, adding water wetter or 30 below to your radiator fluid, (whatever the mixture or choice) will provide more efficient cooling solely by the benefits of the adhesion promotors which is the most important aspect of those products other than lubricants and corrosion resistors.


Sorry for the long posts, and no, I don't work for Red Line oils (water wetter) lol......

mark-------


You're right that ultra pure water is a poor electrical conductor. In fact, absolutely pure water, if it were possible to achieve that state (i.e. 18 megaohm resistance), would be a NON-CONDUCTOR. It is dissolved material (ions) in water that make it conductive. However, the purer the water is, the more aggressive it becomes----it wants to dissolve whatever it comes in contact with (that's why absolutely pure water is impossible to achieve---it dissolves whatever it's contained in). Water is the universal solvent. So, if one were to put nothing but absolutely pure water into a cooling system, it would be trying to dissolve everything it comes into contact with.

[Duke W.]

Re: Radiator cap pressure question?

As many of you know, Joe spent his career in the water industry, and he is absolutely correct! Even "pure" water has a very small concentration of H+ and OH- ions, so it is a weak electrolyte, and it is "hungry" to dissolve anything it comes in contact with up an equilibrium concentration, which is usually low, but strengthens the electrolytic properties.

Going back the to at least the fifties there was a myth that "pure water" does not corrode circulated by people who probably never took a basic chemistry course, and it's still around.

Modern antifreeze products, both OAT and HOAT have sophisticated corrosion inhibitor packages that have been extensively tested to meet various industry and OEM standards, and cooling systems are designed to have sufficient heat transfer capacity to provide proper cooling with up to 60-70 percent ethylene glycol, even though a water-glycol mix has less heat capacity than straight water.

Duke

[Mark B.]

Re: Radiator cap pressure question?

Well speaking for those of us who have taken basic chemistry, I think we have laid out information on an alternative to antifreeze clearly for people to make an educated decision on coolant if they need better coolant performance.

I agree 100 Percent with both of you fine gentlemen.

To be clear, for people still interested in alternatives to antifreeze, I was suggesting demineralized water not pure water, never suggested pure water that would be impossible anyway, and do not use pure water!.. (btw if you have pure water you are a nobel prize winning chemist and you don't need any help with coolant)..also never use tap water, both of which are highly corrosive.
I agree any water can cause corrosion in contact with dissimilar metals without the use of a corrosion inhibitor which I also suggested.
I personally still wouldn't use antifreeze unless its freezing.