Ok, the Celica has been leaking coolant near the thermostat since I bought it.
I got a new t-stat and rad cap yesterday and began unbolting the tstat housing and it leaks much worse. (I knew this- my plan is to swap iot outside today- it's a balmy 19 degrees outside..) I think the studs fixing the t-stat housing may have been stripped- any ideas? self tapping nut??
The kicker- the temp guage will sit at actual temp for a few moments then shoot up to the highest part of the guage- no matter what the actual temp of the coolant (now water)is.

I'm also noticing a brown film as the rad flushes out- it's not oil, just crud imho.

Is there any way to clean off the temp sensor- if it's dirty would it act like this? The temp sending unit is in the same housing (rad side, lower hose) as the t-stat.
Another thing, the Haynes manual (which covers 5 engine varieties) show a small hole "air bleed valve" in the t-stat which the replacement I just got yesterday does not have.

Any input is greatly appreciated..