First of all make sure the coolant is not boiling hot, luke warm is ok.
Remove coolant resevoir cap slowly to release pressure, put the cap back on but dont screw it tight.
Next remove Passenger side Grill to reveal a hole there will be a plastic cover in the way just pull it to the side to reveal the side of the bottom of the radiator.
Grab a piece of garden hose or any hose and put it into a bucket and the other end into the nipple on the side of the radiator then turn the red screw if its tight just crack it open with a flat head screw driver and keep turning and turning until it gushes out. you'll probably loose some coolant/water i did!
When the coolant has finished draining locate the stat housing which is situated underneath the alternator near the front/side of the engine its held on by two allen key type bolts remove them one by one BE WARNED there may still be coolant in the pipe and behind the stat. when the bolts are undone remove the pipe to the side, it'll move because the pipes rubber and flexible. now the next bit i did with pliers as i saw water trickeling out behind the stat i grab the end of the stat and slowly pulled the stat out it should just remove nice and easy.
Recover the old stat and seal and set it to one side. my new one was a little different as the rubber seal was part of the stat so they both went in together but yours may be different or the same? the old one was a seperate seal if it is seperate then it has been said to put the seal in first then the stat.
OLD AND NEW STAT
when the stat is placed in grab the pipe and place it into place then fit the bolts and tighen carefully i think its 11lb ft torque but i did it until i felt it was safely tight.
I then tightend back up the bleed nipple at the bottom of the radiator removed the hose and made sure it was tight so there wer no drips.
Now the next stage is upto you. i filled the car back up with water and got it up to temp to make sure there were no leaks as it there was leaks you wouldnt want to be wasting your new coolant!!! i filled it up with water and checked for leaks (were not leaks) so i drained the water out (gives the system abit of a flush in the process)
then tightend the nipple back up and re filled with coolant i put around 2l of g13 and the rest water
Last bit is to bleed the system:
Slide the passenger side heater core coolant hose 3/4 way off. You want the highlighted hole (red arrow in earlier pic of the heater core hoses) to be exposed beyond the plastic flange.
Once the coolant tank is full and isn't going down in level, raise the coolant reservoir above the level of the heater core bleed hose. Keep the reservoir raised and full until coolant comes out of the heater core. The bleed hole is at the top of the hose so any air comes out of the hole and you can see a few sprinkles coming out of the hole in the above pic.
Do this with the engine running at first. Once the engine is warmed up and any air bubbles have come to the heater core, you can do this with the engine stopped. Leaving the heater on hot won't get the coolant out of the heater core since it's always running through. until the car is cool and then add coolant/water until the level is between mix/max. If you open the reservoir while the coolant system is hot, scalding coolant could spray out so be very careful opening the coolant system while it's hot and pressurized!
Recheck that the radiator drain and all clamps have been retightened. Check the coolant level.
Test drive to normal operating temperature and check the coolant level again. If it didn't go down, you got all the air out. If the level went down, drive around and then do it tomorrow. Any bubbles will make a gurgling sound behind the dashboard. The next day, most of the air will be in the heater core or will have already come out. Repeat the bleeding procedure and top off the coolant.
ANY questions please ask
