How well does coolant mix inside the engine?

Maintenance/Repairs
21

WOW, if you have 3 quarts of 100% water in it, then just add 3 quarts of 100% coolant (that makes 6 quarts)… Then add the remaining 2 quarts (for a total of 8 quarts) of premix or premixed 50/50 coolant to top it off… How hard is that?? I can even count all that on my fingers, didn’t even have to take my shoes off to count, and I am just an old uneducated redneck… :crazy_face:

Yes coolant mixes in the engine and rad pretty fast when the RPMS are up a little, I normally turn the heater to max hot and run the engine about 1800 RPMs to bleed the air out, unless it has to be done differently for whatever reason… Once you have very hot air coming out of the vents for a few minutes, you should be good, drive it around if you like and then let it cool back down and top off as needed…

BTW, you can be an undercar expert (steering & suspension and alignments) pro mechanic, doesn’t mean you are an expert in cooling systems…

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22

I don’t think that this is a problem for George. The current temp in San Jose is 58 degrees, and it is projected to go into the 60s by next week.

That is a very good point.

23

The is especially obvious because an engine is pretty much ideal for mixing, with multiple flow paths splitting and recombing.

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24

We should be careful what advice is given here. Filling a 30 year old vehicle may be quite different than what most people drive. According to one shop the coolant must be filled using a vacume device in order to not have bubbles in the cooling system of modern cars. A bubble in the wrong place can destroy an engine and just running the engine will not fill all parts of the cooling system.

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25

Very good point @Bing. I tried to give your post a “like” but as you are aware giving “likes” is quite a challenge here… It went to the post above … lol … not dissing that poster of course.

26

I"ll do it that way next time. It’s a step in the right direction…

27

I’ve heard they pump about 1.5 million quarts of coolant over 60k miles . Good reason to keep the cooling system well maintained. Easier to replace the coolant than replace the pump.

Math quiz: wondering, does 1.5 million quarts over 60k miles equate to over 10 gallons per minute? Presume freeway travel speed, 60 mph.

28

No, about 6 gallons/minute. All the sources I’ve found have rates much higher than that.

How did your podcast mechanic justify his claim?

29

About the same. Maybe it is less b/c the flow of air through the radiator from the rapid speed closes the thermostat more than you’d think.

No justification provided, other than experience. You might be able to search the website for more info on this topic

30

Not going to, I know he is wrong. I’ve worked over 40 years on heat transfer, mass transfer, and fluid flow problems. He’s mistaken.

31

The claim is definitely counter-intuitive. Which is why I asked. Could apply to certain engine configurations possibly.

32

The water pump continues to pump water through the engine while the thermostat is closed. After reaching operating temperature, and the coolant passes through the radiator 2 or 3 times (less than a gallon each pass), the coolant/water is mixed.

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