Opinions on engines lasting so long with broken cooling systems?

[justme262]

I have many times seen 109s and spits venting light coloured vapour from the radiator area and after a while it stops coming out but the plane continues to fly on at combat speeds.
I wondered if this was maybe coolant or fuel. But it comes from the radiator. I recall being hit like this and my engine giving out sometimes and other times it flys on as if nothing happened. I think it needs some testing to get a better sense of what is really happening.