Getting hot
 

Before Christmas I decided to drain the coolant system and put fresh stuff in. Once I did it I left it idling for about 20 mins and the temp sat at half which is where it normally sits.

Not been driven till tonight, drove it home which is about 12m miles and noticed when I pulled up the temp was just above half way and slowly rising so I switched it off.

I'm guessing this could be an airlock? If so what's the best way to bleed it?

I bought the coolant from importcarparts.

Found the issue. Noticed the road had went lines up and down it, coming from my car.

Can't find where it's coming from but managed to tighten the drain bung half a turn so hopefully it's just that. Waste of time doing that then as most of the coolant is on the floor.

Doh! Refill it when the car is cold, burp it with the top rad hose and the header tank cap off. Then put cap back on run it up to temperature whilst watching the temp gauge.

Make sure coolant circulates through the heater matrix by setting the fan heaters inside the car to hot with fan on. Make sure air comes through warm.

Check the fans on the radiator kick in when its up to temperature. If you still have a leak, it should show itself pretty quickly as the system pressurises... :)

I did a coolant change recently on mine and read that a good tip is to slowly fill the system from the hose that comes off the back of the header tank to the turbo. Just unplug it from the header tank and slowly fill with a small funnel shoved in the hose end. This allows the coolant to effectively fill from the bottom up and minimise risk of airlocks. Pretty much as per http://www.type-ra.com/subaru-forum/...e-guide.19670/

Brilliant thanks Steve. Have just filled it up, wasn't cold but was just under a quarter temp. Will see how it does on the way to work tomorrow.

Didn't even make it to work, got half way and lost all the water and started to get too hot. Can't see anywhere obvious so going to try to get it on the ramp at work.

Any joy finding the leak? Bottom radiator hose getting as hot as the top one? If not thermostat could be duff.

Plastic tops on radiators are known to crack and leak under pressure so check that too, could be along the front side so not obvious as coolant will leak down between the rad and the air con matrix. Even less visible if you have one of the aluminium slam panel cooling things fitted like this:
https://shop.r10s.jp/laile/cabinet/0...mg34450258.jpg

A lot of the newage cars are getting to the point where the original radiators are pretty shot now anyway...

Tried another header tank cap in case your current one is duff? Although I'd expect it to be obvious if the coolant was leaking out of here, it might not be holding the system at the correct pressure.