Coolant Freeze Point For You Cold Weather Guys...

[harrydunn]

Had my cooling system flushed yesterday. Tested the freeze point when I picked it up and was surprised to see only +5 degrees from the radiator. Overflow tank read -40 degrees which I suppose indicates they dumped straight anti-freeze in there. I suppose I'll drain a bit from the radiator and replace with straight coolant to get to -10 degrees or so for Missouri winters. My Grand Prix coolant is showing about -5 degrees so I may leave it alone.

1) What freeze point will a typical 50/50 mix of coolant and distilled water yield?

2) What mixture are you "cold weather" guys running and what freeze point are you seeing when you test your coolant?

Thanks.

--Mark

 

[96r50]

Had my cooling system flushed yesterday. Tested the freeze point when I picked it up and was surprised to see only +5 degrees from the radiator. Overflow tank read -40 degrees which indicates they dumped straight anti-freeze in there. I suppose I'll drain a bit from the radiator and replace with straight coolant to get to -10 degrees or so for Missouri winters. My Grand Prix coolant is showing about -5 degrees so I may leave it alone.

1) What freeze point will a typical 50/50 mix of coolant and distilled water yield?

2) What mixture are you "cold weather" guys running and what freeze point are you seeing when you test your coolant?

Thanks.

--Mark

First off, did Fahrenheit ever make sense at any point in history?

1) There is a chart on the side of the Toyota coolant jugs. Mine is a Canadian part number, but I would be surprised if they are not the same product.

50% coolant: -37C to 109C (-35F to 228F)
65% coolant: -56C to 134C (-69F to 273F)

2) Mine is somewhere over 50% coolant, and I will eventually test it.

HTH!

 

[jasonmt]

50/50 should take you down to ~-30°F, I run ~65/35 (AF/H20) and see ~-60°F.

 

[turbocruiser]

According to my fancy coolant tester tool, -34 is exactly 50/50. I make sure my coolant can deal with -40 in the Winter and then I take it to -20 in the Summer for slightly more cooling capacity coming from slightly higher percentage H2O . HTH.

 

[harrydunn]

Hmmm...seems they may have been WAY off on the percentages given the numbers I'm seeing. Perhaps I'll give it a few days in case my tester was having a bad day.

 

[jlg32281]

I wish I had valuable input, but here I run 20% anti-freeze, mostly just for the lubricants. At night the 80 is in the garage and day time temps below freezing come once in a blue moon. If I didn't need the lubricants and anti-corosive additives, I would be comfortable running 100% water.

 

[Kaoscruizer]

Just tested it last week ... -43 celsius Good enough for me!

 

[turbocruiser]

Just tested it last week ... -43 celsius Good enough for me!

Wow, that's pretty potent! Do you run that through the Summer too?

 

[corsair23]

Hmmm...seems they may have been WAY off on the percentages given the numbers I'm seeing. Perhaps I'll give it a few days in case my tester was having a bad day.

My easy (read lazy) way of adjusting the mix is:

(1) Test the coolant in the radiator
(2) If you are too high on the temp scale (i.e. too much water, not enough coolant) dump what is in your overflow reservoir, fill to full line with 100% coolant, run truck around for a few days (not sure how long is really necessary), recheck (noting the overall change), and repeat if necessary making adjustments to amount of straight coolant added (i.e. first time might be 100%, second round might be only 80%, etc.)
(3) If you are too low on the temp scale (i.e. too much coolant, not enough water) do the opposite of #2

After doing my PHH and flushing my system last year and then testing my coolant I was on the "too low" side of things and I could see that in relatively higher water temps than typical in the summer. IIRC it took me 3 reservoir dumps and fill cycles to get me to where I wanted to be.

Not the quickest method but less messy IMO and you can sort of fine tune your % relatively easy. I was also able to capture the relatively "fresh" mix from the resevoir dumps to brew up some exact 50/50 mix that I desired.

 

[harrydunn]

Not a bad idea there corsair. I may go that route initially and see if I can get what I'm looking for. I wasn't looking forward to unbolting the skid plate and draining from the petcock. Not difficult, just the potential to be somewhat messy. Plus, I was going to work on my diff breather extensions tonight.

 

[Kaoscruizer]

Wow, that's pretty potent! Do you run that through the Summer too?

My buddy is a Toyota master mechanic .. he hasn't suggested that I lower the percentage of glycol to water during the summer. I plan to flush the system annually.


We seem to have less summer to worry about and more winter every year!


I experienced the Arizona summer when I went down to pick up my cruiser .. I can agree that there wouldn't be much need for too much glycol there! I am sure more cold weather boyz will chime in on their experience.

 

[Squash]

Coolant does two important things here, first it lowers the freeze point in winter and secondly it raises the boiling point in summer...

In winter your coolant can gel/freeze blocking hoses creating an obstruction to efficent cooling and overheating.

In summer you want the higher boiling point to ward of steam...

Water freezes at 32f US or 0C Can
Water boils at 212f US or 100C
What do you want your coolant to do?

Do not run pure coolant it must be mixed at ratio.

Test your coolant it is a cheap PM

 

[turbocruiser]

My buddy is a Toyota master mechanic .. he hasn't suggested that I lower the percentage of glycol to water during the summer. I plan to flush the system annually.


We seem to have less summer to worry about and more winter every year!


I experienced the Arizona summer when I went down to pick up my cruiser .. I can agree that there wouldn't be much need for glycol there! I am sure more cold weather boyz will chime in on their experience.

Makes sense, I'm not saying or suggesting it is too much, especially for Alberta Summers, I was just wondering. BTW even in really hot climates the coolant helps avoid corrosion, electrolysis, etc.

 

[96r50]

Makes sense, I'm not saying or suggesting it is too much, especially for Alberta Summers, I was just wondering. BTW even in really hot climates the coolant helps avoid corrosion, electrolysis, etc.

Agreed. The numbers I posted above for each mixture (50% and 65%) are the freezing and boiling points of the mixture. So 65% coolant provides better protection from both freezing and boiling over than 50% does.

 

[Kaoscruizer]

We essentially have the same weather as North Dakota or Montana. I have always had a block heater in my vehicles up here. This cruiser is the first vehicle I have had without one, so I wanted to make sure the coolant was properly mixed. Very true though .. a very easy PM related job.

 

[turbocruiser]

Agreed. The numbers I posted above for each mixture (50% and 65%) are the freezing and boiling points of the mixture. So 65% coolant provides better protection from both freezing and boiling over than 50% does.

Right, but that isn't to be confused with cooling system capacity (capacity not in volume but ability to allow heat transfer); IOW the higher the ratio of water, in general, the more cooling system capacity. The freeze and boil numbers don't necessarily directly refer to capacity. This is why I run the higher ratio of H2O in the Summer than in the Winter. HTH.

 

[harrydunn]

Of course it is also entirely possible that they put TOO much antifreeze in and not enough water. Going to be trial and error I suppose. Since the overflow tank is already reading -40, I may run it a few days as-is and see if that drops the radiator reading any, before filling the overflow with pure coolant.

 

[1r78]

Obviously freezing liquid can exapand and cause damage but too low a boiling point causes the liquid to no longer be in contact with the cylinder walls and the vapor does not have the properties to effectively transfer heat.
By itself ethylene glycol boils at 330F but it doesn't transfer heat very well and its freezing point is -8F. Water is added to improve heat transfer.
Here is a list of boiling and freezing point for Antifreeze to Water mixtures as measured at sea level.
30/70 boils 220F freezes 3F
40/60 boils 225F freezes -12F
50/50 boils 226F freezes -32F
60/40 boils 234F freezes -57F


Notice that the freezing point is what is dramatically changed with the mixture, not the boiling point. Also for every pound per square inche of cooling system pressure increase,raises the coolant boiling point by approximately 2.5F

Cited from Basic Automotive Service & Maintenance by Don Knowles

 

[corsair23]

Obviously freezing liquid can exapand and cause damage but too low a boiling point causes the liquid to no longer be in contact with the cylinder walls and the vapor does not have the properties to effectively transfer heat.
By itself ethylene glycol boils at 330F but it doesn't transfer heat very well and its freezing point is -8F. Water is added to improve heat transfer.
Here is a list of boiling and freezing point for Antifreeze to Water mixtures as measured at sea level.
30/70 boils 220F freezes 3F
40/60 boils 225F freezes -12F
50/50 boils 226F freezes -32F
60/40 boils 234F freezes -57F


Notice that the freezing point is what is dramatically changed with the mixture, not the boiling point. Also for every pound per square inche of cooling system pressure increase,raises the coolant boiling point by approximately 2.5F

Cited from Basic Automotive Service & Maintenance by Don Knowles

That is interesting info - thanks for sharing...

I'm inclined though to agree with turbocruiser that there is more to the story though. Initially after my hose replacement work and flush and fill my LX ran hotter than what I experienced before the work and flush and fill (with old cruddy coolant no less) - I tested my coolant/water mix and discovered I was in the 60/40 range. I progressively brought that back to right around 50/50 and the temps came back down to what I was used to seeing. We aren't talking a huge difference hear...Somewhere in the 5-10F range which seems to match up with what the data above would suggest.

 

[jasonmt]

The specific heat capacity of a 65%AF/35%H20 mixture at a temperature of 75°C is less than 80% of pure water whilst a a 25%AF/75%H20 mixture at a temperature of 75°C is more than 95%.