Cooling System

I'm fluching the cooling system on my 83 mazda, becasue the idiot before me put straight water in and it froze up.

I unfroze it in my shop, and opened the drain plug, but only like 2 1/2 litres of water came out. I know it's all thawed out too.

So I started the engine figuring the water pump would push out the resto of the water but I only got a bit.

Does a mazda engine only have 2 1/2 litres of fluid in it. I figured it wouldn't be much, but damn, 2 litres?