VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1916-1922 - Model 490 Radiator Coolant/antifreeze

I have a recently restored 1922 model 490 - have been adding water to the radiator periodically. The restorer added coolant/antifreeze. How can I tell when I need to add more antifreeze?

I have an antifreeze tester, but it seems to be designed for the reservoir in modern cars.

Is there a leak in the cooling system?
I have no leaks. I keep the cooling system filled with a proper mix of antifreeze and water all the time. Before I start a new driving season I often need to put a couple of decilitres of the proper mix in the radiator. As the engine and the radiator is cool, I fill the radiator up to approximately 70 millimetres under the opening of the filling pipe. If I fill more, coolant goes out through the owerflow pipe as the coolant gets hotter.
In the driving season I drive quite a lot, so now and then I check the coolant level. Sometimes, after hard (!) driving, I have to add some coolant, maybe one or two decilitres, with a proper mix of antifreeze and water.

If you have added only water several times and do not know how much water you have added I recommend that you change all coolant, also to check if it is clear or if it contains some or a lot of rust particles.

Thank you so much for your thorough reply, Per-Ake. Very helpful.

No, I don't have a leak in the cooling system. It's just been really, really hot this summer where I live, so I've been monitoring the fluid level in the radiator. The fluid does have the necessary green tint. Today, I added a few ounces of coolant/H2O. All is well.

Again, thank you, sir.