Slowcrash_101

I noticed that in a half year period since I did work on my A/C I've lost what looks like ~75ml from my overflow bottle. I know I spilled some and afterwards it was just above that plastic bump right next to the max line. I checked it yesterday when I was topping off my oil and I noticed that it's slightly less than back then maybe about 75ml. Just for my peace of mind I'll be doing a UOA next month when I do my next oil change, but am I just being paranoid? Can this lower level just be attributed to evaporation? For the record I've put about 4,300 miles since then, this was back in late May.

*The car is parked outside but in the shade, and it's regularly over 90 degrees here in South Florida.

JohnsS2000

closed system, should be no loss. In order for liquid to evaporate it has to have escaped into the atmosphere.

darcyw

the coolant in my overflow does go down a little, but that's because the upper lid is not completely leak proof. I see some splashed about on the bottle itself especially after autocross days.

darcy

steven975

I see some fluctuation with temperature. Sometimes the overflow is close to Low, sometimes close to High. I have not had to add any coolant in years, though.

Slowcrash_101

Pressure tested the system it's holding 15 psi no leaks that I can see, I did say it was at the overflow. I'm probably overthinking it.

jkelley

Unless the radiator cap open or pulls coolant to/from the overflow tank... and the overflow tank is atmospheric, essentially. However, with the coolant in the water (assuming 50/50) it depresses the vapor pressure of the water quite significantly I would imagine, so losses should still be minimal

fredsvt

I have noticed with all makes running long life coolants, that there's a very gradual drop in coolant level over time, with regular use.

As an example, my S in 3 years and about 10k has dropped about 1/2" in the reserve tank. My '04 6 speed Accord drops about 1" to 1.5" in the course of a year, and I've never seen a leak.

Usual tell tale signs of any extended life coolant leak like Type 2 is that smell.

My 99 Ford Lightning, now filled with Type 2 sees little drop, as it's rarely used, maybe 1000 miles a year at most.

At work, I routinely see Hondas of all models come in below the "low" mark and ones who Jiffy Lube between major services or check overs, come in sometimes empty, with no leaks seen.

I see Toyota, Nissan, Hyundai, Kia and many GM cars do the same thing.

Cars with degas bottles (pressurized tanks) instead of atmospheric recovery bottles don't seem to have as much of an issue with this.

nissanfanatic

I would imagine it happens quicker in a car with a higher percentage of water to coolant.

I haven't ever really noticed any in any of my cars so long as the cooling system was operating correctly.

flanders

OP do you have silicone coolant hoses?

windhund116

Slowcrash, You try a new radiator cap?

You see any tell-tale signs of coolant overflowing the fill tank? See water stains in the engine compartment? Could be overheating, due to a clogged radiator.

No mixing of water into the oil or vice-versa?