I picked up a 1.6 Eunos automatic not too long ago and am currently doing some first time maintenance. Recently had a pressurised coolant leak/spray appear seemingly from around the top of the T piece in the thermostat housing, but upon closer inspection it seems like the only damage is to a brown, plasticy seal surrounding the metal piece (see image attached).
The metal piece itself seems completely fine visually so I’m wondering if anyone has seen a similar issue and if I would be safe to just tightly reseal the T piece and connected hoses with electrical tape? Maybe even replace the hoses, if that is more likely to have been the cause of the leak? If not, is there any other diagnostics you would recommend to try and nail down what the cause might have been?