Anti-freeze concentration

Is there an easy way to determine the concentration of antifreeze in the heat exchanger? I changed antifreeze in both engines but I was not able to get all of the old mix out. The drain plugs are seized so I had to suck it out of the radiator cap and open one of the lower hoses to get the fluid out. I added a 50-50 mixture of new fluid. I wonder what is best way to verify if I now have 50-50 mixture or less in engine since old fluid mixed with new. Also I want to check I don't have leak and losing mixture out; being replaced with sea water. Does specific gravity work for antifreeze?

it does, also the freeze temperature is a good way to test and testers are readily available.
The AF you used should have a chart of temps and concentration on the container.

Auto parts stores have inexpensive turkey baster type testers for determining freezing point of anti -freeze in systems. The really cheap ones have little balls that float (or not) and the slightly better ones have a pivoting pointer. They are testing the specific gravity. Run engine up to temp and check in radiator cap. That should represent the entire system if the thermostat has opened.

bilge53 said:

Auto parts stores have inexpensive turkey baster type testers for determining freezing point of anti -freeze in systems. The really cheap ones have little balls that float (or not) and the slightly better ones have a pivoting pointer. They are testing the specific gravity. Run engine up to temp and check in radiator cap. That should represent the entire system if the thermostat has opened.

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The 'turkey baster' tester is a hydrometer and available everywhere (Wally world included) for $2-3 bucks.

Specific gravity is what it tests which relates to the mixture and protection provided by the anti-freeze.

For best performance I read and hear 40-60 mix (AF-water) is ideal ... not 50-50.

50-50 prevails because it's easy to remember and mix and covers the freezing issue even if you live on the shores of Hudson Bay. I had heard that less AF than 50-50 was best for anti-boil and other issues but most car mechanics and equipment manuals still say 50-50. That sells AF too.

When I had a water cooled BMW motorcycle it said 60-40 was best. As I recall 50-50 is good down to about -40f so it's obvious nobody on the Pacific Coast or Florida needs even close to that much freeze protection but anti-boiling protection would be a plus.

I don't know ... does viscosity and flow rate enter into the picture and there are other factors that enter the picture too but I don't know what they are. There is corrosion and longivity ... but what else?

I know 50-50 is close enough for all practical purposes and if your local temps go below -40f you need more AF but what is ideal ... excluding the freezing factor. I know it's hard to exclude the freezing factor as the stuff is called anti-FREEZE. But assuming one lived in a place that was always 70 degrees what would tha ideal AF fluid be?

They call it "coolant" because it not only protects against freezing but against corrosion and has better heat transfer properties than water alone. The maker of the coolant usually provides information on the best ratio to water.


BTW: Distilled water is best for mixing and it's less than $1 per gallon at grocery stores.


And yes, you can buy a tester at an auto parts store or Walmart.

WesK said:

They call it "coolant" because it not only protects against freezing but against corrosion and has better heat transfer properties than water alone. The maker of the coolant usually provides information on the best ratio to water.


BTW: Distilled water is best for mixing and it's less than $1 per gallon at grocery stores.


And yes, you can buy a tester at an auto parts store or Walmart.

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Actually it doesnt have better thermal transferal properties than water.

Antifreeze or coolant has as much voodoo attached to it as "what anchor?"

Certain diesels like Cummins and Cat are specific in their requirements. Read the manual if yours is specific.

Many owners just pour in their own liquids because they heard something in the pub or that's what they did on their '56 Chev in high school.

Eric, with all due respect, a BMW motorcycle has nothing in common with a boat diesel and probably demands a proprietary product like Mercedes does.

Wes, you're correct about freezing and corrosion, except for the heat transfer but that's splitting hairs on my part. The mixture will have a higher boiling point than straight water, even higher in a pressurized system and will also prevent cylinder barrel corrosion and possible localized overheating.

Engines with wet liners and engines with any aluminum in contact with coolant are picky on chemistry.

Cummins B and Lehman 120 fit neither category, except the head tank on the Lehman, I don't think there is any other Al in the loop. With no liners and no Al, you can be a bit casual on coolant.

Yanmars, Volvos, and anything that uses a lot of Al, and anything with wet liners, read the manual and use what they suggest.

In the NC area, we like to use 33% glycol. 1gal coolant, 2gal distilled. Wet liner engines get tested for SCA concentration and dosed as needed.

And yes, glycol mix is not a better coolant. Higher viscosity, lower thermal conductivity and lower specific heat. Only thing better is raised boiling point and lowered freeze point.

Some engines with marginal sized coolers will overheat with too much glycol.

Xsbank said:

Many owners just pour in their own liquids because they heard something in the pub or that's what they did on their '56 Chev in high school.
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Unfortunately this is the case too often. It is even the case with some mechanics I have met.

"not only protects against freezing but against corrosion and has better heat transfer properties than water alone."

NO! it does not cool "better" at the same pressure.

Antifreez has only 3/5 the cooling ability of water , however a 16PSI pressure system will overcome this handicap by being hotter , and there for better able to get rid of BTU.

The higher temp differential does the job, not the antifreez, except it gives a higher boiling point.

Most old boat engines have 3 -5 PSI pressure caps and run 180F or so normally.

About 35%- 40% antifreez will be the better compromise in non freezing areas for the best cooling with all the anti corrosion and water pump lubrication anti freez does give.