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Antifreeze/Water Mix

7K views 10 replies 6 participants last post by  carlrover 
#1 ·
All,

I finally got around to actually testing my coolant mixture after I did the total flush and change. The thing is telling me that I am around -35 or -40. I expect this means that I didn't quite get enough water in the mixture. Am I ok with this or do I need to somehow drain coolant in order to add more water?
 
#2 ·
Did you replace your t/stat with a new 180 degree, did you you distilled water, how many miles on the radiator?
 
#4 ·
Next time it starts running warm might want to consider replacing the radiator cause it is normal for ours to plug up with calcium above 100,000 miles and it can't be flushed out.
 
#6 ·
Short story:

You're probably fine.

Long story:

I think you're overthinking your coolant. 50/50 is the industry standard for "most" cars that drive in "average conditions". Typically this means moderate winters and summers, but no significant temperature extremes.

Most people think that the use of antifreeze somehow aids in cooling - it doesn't - it's purpose is right in the name - to prevent water from freezing and cracking the block in the coldest winters. Yes, ethylene glycol will raise your boiling point somewhat, but taking into account the 15psi of pressure in the typical cooling system, 50/50 will boil at roughly 265F while pure water will boil at 257F. I think you'll note that if the temps in a typical engine get anywhere near this, the block is already toast.

In fact, running pure, distilled water in your cooling system will yield the absolute best cooling benefits, as water has a higher specific heat than 50/50 and can thereby radiate more of it out through the radiator. Do I recommend this? Hell no. The first freeze will crack a giant hole in your block, also small leak could cause your system to de-pressurize, boiling your coolant.

Getting the right ratio of water to coolant is the decision of the driver, much like oil. If you live in very hot climates where freezing is unlikely or impossible, you can use a ratio of 70/30 (water:coolant) comfortably. This will keep the block from freezing above 0F and it will yield much better heat transfer so your engine will run cooler in the summer. If you live in the north, where temps can dip well into the negatives, you should run 50/50 or even a 60/40 antifreeze bias to ensure against freezing in even the coldest temps.

I live in Florida - temps between April-October typically hover in the low 90s with 90% humidity and the coldest temp you could expect to see in winter is the low 40s, as such, most of my cars run 60/40 water bias to help with the cooling. I haven't had any problems. Even last weekend when I went trail riding in Ocala when I had 900 lbs of people in the car on 90F day with the AC on I didn't see coolant temps above 195.8.
 
#8 ·
#7 ·
Thank you for the explanation Bosnian. When I refilled my antifreeze, I had first flushed several times with water so my engine was full of water. Then I just topped off with antifreeze thinking I would get about 50/50 in the end since I just drained out of the radiator hose. Looks like I got too much antifreeze.

I'm thinking about sucking some coolant out of the reservoir and adding water to top off until I get to about -25 on my checker tool. I know it won't get any colder than that where I am at and probably won't get below -15.

With a 50/50 mixture, what temp will you typically be good for?
 
#9 ·
Another Note on Coolant....

The 50/50 coolant/water mix is not just for freeze protection, but also to prevent coolant breakdown, provide efficient heat transfer, and provide adequate corrosion protection. The breakdown of glycol (the active freeze protection component in coolant) into its acidic forms only typically occurs at lower glycol percentages (10-30%). This is why maintaining 50/50 coolant/water is important. While glycol's only purpose in the cooling system is to prevent freezing, 50% water still allows for decent heat removal, and the amount of glycol (30-50%) helps prevent chemical breakdown/degradation.

Straight tap water is corrosive and distilled water is even more corrosive. Aluminum is relatively corrosion resistant within the pH range of 7.5-8.5. It does, however, corrode at both ends of the pH spectrum (<7.5, >8.5) Therefore, it is critical to maintain a pH of 7.5-8.5. The typical "green" coolant does this and is not just glycol and water. It also contains silicates, phosphates, etc. High levels of phosphate aid in stabilizing the glycol and prevent it from breaking down. The silicates provide direct corrosion protection via a filming mechanism. As the cooling system runs, the silicates create a molecular barrier (film on a molecular level that you will never see) over the metal parts, aiding in preventing the corrosion reaction. The chemical reactions involved in Silicate chemistry are complex and not completely understood, but we know that in closed loops, like an engine system, it works well.

In short, it is important to use the correct coolant/water mix in order to protect the engine. Straight water offers better cooling and heat removal, but coolant is necessary to protect the engine. Too much water or coolant could throw off the pH, corrosion protection, cooling capability or freeze protection. Its not a good idea to use 100% water, or 100% glycol, unless the system is specifically designed for it.
 
#10 ·
Antifreeze/coolant actually raises the boiling point, not lowers it. Even though the temperature, overall, should never reach the boiling point, even with pure water, there can be hot spots in an engine that don't get reflected by the temperature gauge. There's the risk, using pure water, of those hot spots causing the water to boil at those spots and so loose nearly all of it's cooling ability. It's called the Leidenfrost effect.
Even if coolant doesn't do as good a job removing heat compared to pure water, it does a much better job than steam.
 
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