Does the ambient temperature affect your overflow tank coolant level like it does your tires? Or is it my silicone hoses that are making me add 100ml of coolant a year?

 

I don't think water's volume changes much between 4 and 99ºC at sea level.

The formula shows that one liter (1000ml) of water at sea level expands 12.8ml from 20º to 80ºC. (68º to 154ºF). Remember, the coolant is under more than one atmospheric pressure due to the radiator cap (S2000 OEM = 1.1 atm pressure). So, the expansion is probably less.

"This equation is usually written as ΔV = βVΔT, where β is the coefficient of volume expansion."

 

Standard silicone hoses for sure will make you need to ad more, usually you can even smell it under the hood.

 

The question is why does it expand? Is it higher temperature causing lower atmospheric air pressure which then allows the water to expand, or does the liquid itself expand or contract, and the level change is a compounded effect. Oil for instance expands with temperature, but then again the chemistry of motor oil is different than water.

If air pressure and temperature are what causes the coolant to expand and contract, then cold weather would have naturally denser air, which would then affect the coolant level, since the level is the difference between the radiator and atmospheric. But as you stated it should only be ~10-12ml not 100, I'm guessing the rest is just evaporation through the silicone coolant hose.

 

Most things expand with heat. Contract when cold.

 

An aside: What are the advantages of using silicone-based hoses over rubber types?

Thanks!

 

I guess they could have a longer lifespan and a bit better temperature ratings.
Some more reading here: https://motoiq.com/silicone-radiator...or-the-street/

 

Thanks!

In my experience, the OEM Honda rubber ones have lasted long. On several Hondas (including dirt bikes) and Acura cars, that I've owned.

The porosity of the silicone type would be a worry for me. But I'm a worried wart.

 

I just replaced the stock radiator hoses on my 165,000 mile car. They were still in such good condition that I kept the old ones as spares lol. I did it because I had a bunch of other stuff apart and it was a bit easier to do it then than later. Probably could have run them for a good while longer but with my luck, I know when they went they would go on the track and ruin a track day !

 

I changed mine because my car came with an Comptech intake, and the coolant hose that replaced the one under the throttle body was leaking, I got silicone hoses for free 99 so I just put them on.