Possible overheating causes?
 

The car overheats when stationary and lots of air and hot water come out of the coolant overflow pipe..

What are some possible causes of this?

Could it be that the thermostat has messed up? (I am going to try to take this out of the car now and check it)

Or that there is a leak somewhere in the line which is letting air in?

What are the most likely reasons for the overheating?

I just had a big fight with this, and ended up listing and discussing every item it could be.

My issue ended up being resolved by replacing every piece of the cooling system, but that doesn't mean it's the same issue with you. Try reading the thread (rather than me re-typing everything here) https://www.rx8club.com/trouble-shoo...eating-236766/

Did you do it all yourself? Do you think an amateur would be able to it? Are there instructions on how to change the different parts of the cooling system?

If you have basic metric tools (sockets, extensions, wrenches, etc.) it isn't too hard. It is time consuming though. The workshop manual really helps, there is also a DIY on replacing the radiator, which is the most time consuming part. I have several pics on my coolant issues thread https://www.rx8club.com/trouble-shoo...roject-218810/

Yes, I do all my own work. It isn't hard, just involved. Plenty of things to be aware of ahead of time.

First thing to check is if the fans are working correctly. The next most likely are the thermostat and waterpump. There could be a blockage in the radiator or one of the hoses..but less likely

Could also be a bad coolant seal in the core. That would have case though :(

Or the ECT sensor

You're right! The main fan fuse popped which stopped all 3 fans from working =/ I should have really spotted this before...

But YES! She lives =D