[bga]

I've seen these things at auto supply shops (Repco in Australia) they're designed to replace or augment a coolant pump, although the one I saw looked too feeble for big motor. I have thought that these would be ideal for EV use and in the correct pumping power range to cool a motor controller nicely. Presumably, they don't mind having hot water in them.

Another possible source is a marine water pump, such as the 'Whale' type.

My only concern with these sorts of pumps is to make sure that the plumbing is arranged so that the pump will prime reliably.

One fellow in WA uses a 4 Litre plastic (oil?) container on a Zilla 1K controlled system for his 'radiator' and has found that to work well.