Just a gal fixing a Jaguar in her driveway, but wtf is this nonsense?

Edit: it worked and it drives again. Now to solve the oil leak it has

Picked up a significant coolant leak, added UV dye and found this piece of shit was pouring coolant because of course the thermostat housing is plastic. Coolant doesnt eat plastic and cause the seam to fail at 125k miles, right?

Oh and every overflow connection is plastic, so we are $250 deep in replacing those brittle POS’s also. Hoping this fixing the issue