Coolant Mixture Check, Hot or Cold?

Post by **MrAl** » 01 Jul 2016, 08:26

Hi there,

How do you guys check your coolant mixture for winter preparation?

Do you:

1. With the engine cold, take off the overflow tank cap, start the engine, warm it up good, then test with a tube and ball tester?

or:

2. With the engine cold, take off the overflow tank cap, dont bother to start the engine, then just test right away with the tube and ball tester (so the water is still more or less cold)?

By 'cold' i just mean the car has sat overnight so maybe the coolant is at the regular summer outside ambient temperature say 72 degrees F or thereabouts.

I've read both on the web, so does the coolant really have to be hot to test or can it be cold?
Doing it cold is obviously much simpler, but if it has to be hot then i will do it that way.
After having the fluid replaced i want to test myself, and also test again just before winter comes.

Thanks again.

Post by **erikv11** » 01 Jul 2016, 09:01

I've actually never used one of those, but surely they are designed to test the specific gravity of the coolant at ambient (cool) temperature. Dozens of people would be scalding themselves if there were any other recommendation.

Post by **MrAl** » 01 Jul 2016, 09:46

Hi,

I was hoping that was the case

I'll be checking it soon too.
I wonder why they say it has to be hot in some places? Maybe just misinformed.

The other funny thing with this car is that there is no rad cap, just the overflow tank cap. So that means if i add anti freeze i cant test the mixture right away. I have to drive the car a few times to get the mixture to mix thoroughly...what a pain.

Post by **MadeInJapan** » 01 Jul 2016, 10:04

I always mix up the antifreeze and distilled water in a separate jug and pour it in there- never in the overflow tank itself. I just guesstimate. I never am accurate!

The coolant capacity in our cars is 7.6 quarts for non-turbo and 7.4 quarts for turbo models. With the tester you mention, you will be able to calculate what mixture to add to what is in there to get your "winter" mixture correct, but to be honest, I have never changed the ratio all year long and unless you live in the arctic, I would not think that this would be an issue. If coolant needs to come out of the system, you can use a turkey baster to suck it out. I prefer doing that to undoing the petcock at the bottom of the radiator (they get brittle and have been known to break) or detaching the lower radiator hose (a better option but still a pain).

Post by **erikv11** » 01 Jul 2016, 10:13

MrAl wrote: ... The other funny thing with this car is that there is no rad cap, just the overflow tank cap. So that means if i add anti freeze i cant test the mixture right away. I have to drive the car a few times to get the mixture to mix thoroughly...what a pain.

Yeah, and make sure the thermostat opens too, basically you need a good 10-15 minute drive for good mixing.

kippster41493 · Post by **kippster41493** » 01 Jul 2016, 10:22

I've never switched the ratio either, I am wondering now that you say "unless you live in the arctic" I live in Wisconsin which is basically the same thing during the winter. We have averaged well into the negatives (-20 average) through out the past few winters and I'm wondering if I should be a little more worried about the correct ratio?

Post by **MrAl** » 01 Jul 2016, 12:35

Hi again,

This car doesnt have a rad cap like the old cars had. The only access to the coolant mixture is through the overflow tank, that plastic tank on the side of the engine compartment. Either that or remove a hose, which i dont think i'd need to do.

I just want to make sure it is the recommended 50-50 mixture, but the tester should tell me what temperature it is good to. It has the temperature readings vs the number of balls that float once you get some of the coolant fluid into the tube which looks like, yeah, a turkey baster

Thanks for the heads up on the bottom drain spout too, i had my doubts about ever draining the fluid that way too. Draining from the bottom hose sounds like a good idea, if it very comes to that.
The antifreeze to water ratio should be 50-50 already, but i want to make sure that's all. It's better for cooling in the summer too from what i understand.

Thanks again

Post by **MrAl** » 01 Jul 2016, 16:23

Hello again,

Little update on this topic...

I found out something interesting. For liquids, the viscosity, density, AND specific gravity ALL change with temperature. The change is toward the less dense and lower specific gravity with increased temperatures. This means that something with constant density would 'float' in a cold liquid better than in a hot liquid, and by better i mean there will be some materials given constant density, will float in a cold solution but will sink when that solution is heated to some temperature.

Enter in the floating ball coolant mixture tester, which i happen to have. Cost $2 (USD).
This thing operates by taking in a small sample of the solution and depending on the specific gravity a number of balls will float, from 0 to 5 balls. The more that float, the lower the temperature of protection. For example, with 5 balls it says -40 degrees F, and with 4 balls it says -25 degrees.

The problem is, those figures represent a predetermined calibration. The manufacturer would have known that certain color balls are made from a certain material (or density) and therefore some will float and some will not float in say a solution that is good for -25 degrees. Since the properties of the fluid change with temperature, that would mean they would have to do the calibration at a certain temperature. That, in turn, means that EVERY measuring device COULD be different, according to how they did it with that particular measuring instrument.

After reading about the change in properties with temperature i fought to find the package the device came in (bought it the other day in anticipation of these tests) and finally found it, and sure enough, on the package it states that the car has to be warmed up first, with the radiator cap off though, so the fluid heats up.

The temperature is quite different from cold to hot, so there could be a significant difference. However, testing cold it shows 4 balls floating. I didnt test it hot yet, but i will tomorrow. I will report back here the difference if any. I am hoping i still get 4 balls floating, but 3 would be good for -10 so that's not too bad i guess. I suspect it is a slightly under 50-50 mixture in there, so slightly more water than antifreeze instead of exactly 50-50, but i'll test hot next and see what happens.

So the bottom line is when all else fails, read the directions

There might be one saving grace: if the fluid is hot, then the balls are hot, but if cold, the balls must be cold too. But then again the balls are solid material not a fluid.

I'm still hoping there is no difference, but some of you guys might know better.

Post by **MrAl** » 02 Jul 2016, 14:05

Hello again,

I tried repeating the test with the engine warmed up but it didnt work. That's because the over flow tank water does not get hot, only the coolant in the engine itself. I tried pumping some into the tank by repeated gentle squeezing of the upper rad hose, but that just got the water in the tank 'warm' not hot. So all i know so far is that i have four balls floating when the fluid is cold, but the test instrument was calibrated with hot coolant, so i have to try something else because it is just not going to ever get hot in that tank. If the rad has a coolant cap like all rad's should, this would be easy to do, but not with this car

My next try is to do a basic experiment with all cold fluids. The manufacturer must have calibrated the instrument with hot coolant, but that doesnt mean i cant re-calibrate it with cold coolant mixture.
What i'll try next is to first test some plain water and see what that reads cold, then mix in 25 percent pure Prestone (lucky i have some) and test again, and finally mix in 50 percent and do that test. This should tell me what reading i get COLD when there is a 50-50 mixture, which is usually the recommended ratio. I'll get back here with the grim details hopefully a little later

Since it still might be interesting to see if there is a difference directly, i'll next heat up the mixture a little and test again. That should tell me once and for all.

This is quite interesting, i just wish it wasnt so darn important. When winter comes i want the car to be ready for the cold.

Post by **abscate** » 02 Jul 2016, 14:36

I think you are over thinking this.

Drain coolant. Flush with hose for 20 minutes. Drain water. Close all hoses tight. Add 3.7 liters pure coolant ( 4 is fine)

Top off with water to full mark. Run car. Wait till it's cold. Add water to mark.

Repeat every 2 years

You can run 50-50 mix year round in NJ or even upstate NY