hello all. new to the site. thought someone could help with my problem. merry xmas btw.

my 2000 audi a4 1.8t quattro had a leak from the coolant flange and o-rings. replaced it and fixed leak which causes pressure to normalize, caused quicker overheating though. replaced thermostat with 180 degree (lower than OE) thermostat because i live in california with high temperatures. now overheats slightly passed middle, but now ive also lost all heat from interior heater (could be heater core). is there anything i need to know that i didnt do properly. or is there anything i can do to fix this problem? anything i didnt do correctly?

thanks for the help!

 

I'm going through pretty much the same thing. Coolant flange leaking. Replace it as well as coil pack & fuel injector harnesses. Now the thermostat is opening at crazy temps (215-230 degrees). Replaced it also and still the same. I'm gonna take the head off tonight.
Have you tried bleeding the air outa the system. Get the coolant reservoir out and above the engine. Get the car to operating tempature and remove the cap. As the system cycles you might some air outa there. Just a thought.