Coolant overflow tank

[Gary G.]

I recently flushed the cooling system on my 75 L48 coupe. I filled the overflow tank up quite high, and over the last month, it has settled a bit. In other words, some fluid "disappeared" while driving. I do not see any leaks, everything is tight, and the car runs at normal temp. I am assuming I overfilled the tank, and it has just purged itself while driving. Am I correct? I do not see any marks on the overlow tank indicating a low or hot level, how much antifreeze should be in the overflow? Thanks for any input.

[Terry M.]

Re: Coolant overflow tank

How about the possibility that there was some air in the engine or radiator, and that air was forced into the overflow tank -- just as the system was designed to.

[Harmon C.]

Re: Coolant overflow tank

The overflow tank should have the same antifreeze mix as the radiator. I usally just guess a 50-50 mix as it's not rocket science.

[Gary G.]

Re: Coolant overflow tank

Lyle,
I had the same mix in the overflow tank, I think I had the tank too full and it burped some coolant out as the car ran. There is no molded mark on the overflow tank indicating a cold or hot level of fluid. Maybe I just overfilled it.

[Oliver B.]

Re: Coolant overflow tank

...I think I had the tank too full and it burped some coolant out as the car ran...

May well be - as soon as the engine (and coolant) gets hot, valves open to let the expanding water flow into the overflow tank.
When the water cools down again, water gets "sucked" back into the radiator.
So it may well be, that the excessive water was drained down the overflow hose of the overflow tank...

Just keep an eye on the system and don't let it run dray (say keep the level a couple of inches above the lower end of the "suction hose" inside the overflow tank). If the level remains there, don't worry!

[Harmon C.]

Re: Coolant overflow tank

When you flush the system you will have air in the system. The overflow tank just replaced the air with antifreeze as it should. It should be OK now but if the oil level goes up and the coolant goes down their is a probem.

[Oliver B.]

Re: Coolant overflow tank

It's most probable that you will notice white exhaust smoke ("burnt" water) then - just keep your eyes open. My guess is, you should be allright now.

[Gary G.]

Re: Coolant overflow tank

Thank you gentlemen. I see no white smoke, and I hope that things will "level out" no pun intended.