No need to "bleed heat" from the motor.
It doesn't get hot. Period. Especially in winter.
OK -back to experimental mode!
A Mr. Coffee Brand Tea Maker
Holds about a quart, and will heat that water to just under 200 degrees f. in about 5 minutes.
On the bottom, it's marked as 700 watts. It was confirmed as 680 watts with my Killawatt.
Of course the tea machine is a bit small to use by itself for an EV heater, but seems like 700 watts would be plenty of power.
To go bigger, something like this could be used.
That's my mother's coffee urn (used for tea) which I had borrowed for the weekend. She loves it, her only complaint is that it gets TOO HOT. I looked on the bottom of the urn. Guess its power rating. 1000 watts!
We are definately talking block-heating power!
Just imagine that coffee urn, unsulated, with a circulating pump! Sounds like a liquid heating system to me!
PS: No, I can't actually use that particular urn,...my mother would kill me!