Hey everyone,
 
As we all know I struggle with everything. Hoping to replace my thermostat+gasket in the next few days.
I'm going to be following this guide for the thermostat (which looks easy enough): Thermostat Guide
I'm also considering replacing this sensor while I'm at it
 
I'm a bit unsure of how to go about bleeding the coolant system (as I assume I have to after replacing the thermostat/sensor). I've read a few guides online and here's what I've got from it, hopefully someone can help me out to make sure I end up doing it right:

- Make sure car is level. Grab the two hoses tied to firewall and put on the radiator bleeder, one on the heater core
- Hang both hoses up (ideally on the "frunk" latch) so they're above the filler neck
- Have heater slider thingy all the way to full heat
- Open both bleeder valves?
- Take off filler cap in engine bay, fill with some coolant 
- Close radiator cap (do I close the bleeders now as well?)
- Run engine at roughly 2500-ish RPM for a few minutes
- Open radiator cap again once it cools down, add more coolant mix
- Not sure from there

How can I tell when all the air is out? Sorry if this seems trivial to most of you, just don't want to cause any major damage haha. Oh and which coolant do I use? I was given some when I bought the car, pre-mixed green stuff.. not sure if it's what I need however; do certain cars need certain concentrates/water-to-coolant ratios, etc?

Not sure on the bleeding thing as I've never done it but with the coolant I thought green was the one to get after doing research and looking up the correct specs, but I have read on the forum that red is the better coolant. When I researched it I was under the impression red was for later cars, but some people seem to insist it's right. I wonder if there's a previous thread anyone can point us to about red vs green?

Hi Hoonsy,
Have a look in the Tech Info/How to section of this Forum.
There is an excellent article titled SW20 Cooling System Maintenance, written by Redtarga.
Provides all of the info & instructions needed.

Yep... as Peter suggests.
Here's the link
http://www.mr2australia.com/mr2play/tm.aspx?m=113820

 
Don't mix green coolant with red or you could end up with sludge.
 
If you want to change from one type to the other make sure you do a thorough flush first. 



 
 

Thanks for the link fellas

Not sure which coolant is in the car at the moment - had the welch plugs replaced about a year ago so coolant was replaced then by the mechanic. I'll have to check

Had a look and my mechanic used a red coolant. Is it safe to assume he used a 50/50 mix as well? Or in other words, if I use a 50/50 mix to top it up, will it have any negative consequences if his mix was slightly different?

Hoonsy
Had a look and my mechanic used a red coolant. Is it safe to assume he used a 50/50 mix as well? Or in other words, if I use a 50/50 mix to top it up, will it have any negative consequences if his mix was slightly different?

For topping up a different mix shouldn't matter much.
If you are worried about it why not ask your mechanic what mix and brand he used. 
 
 
 

If I remember correctly, red isn't safe with brass or copper components (e.g. some radiator tanks for instance).  I ended up selecting green coolant as it works with everything, although at the expense of a slightly more frequent replacement schedule (5 years instead of 6).

Strange as the recommended coolant is Toyota long life red and all the heater lines including the core are brass