Over heating 2.5L STI 2007 Hawk
 

Hi everyone this is my first post, I have recently bought my first Subaru 6 months ago after always wanting one, it is a 2007 Impreza Sti completely standard with blitz catback exhaust and 94,000 miles on it.

When I bought it the car wanted a new clutch so I have replaced this but recently it started to overheat on the way back from Sheffield one day so I replaced the water pump thermostat timing belt and tensioners etc.

The water pump was quite tight so expected this was the problem and it seemed fine for a week or so but now has started to over heat again. I have also noticed a slight misfire under acceleration and on cold start up for the first few seconds of idling. The oil is not contaminated as I have just changed it and neither is the coolant however it throws water into the overflow bottle and then overheats. It is fine as long as I keep topping up the header tank but only lasts around 5 miles before needing topping up and overflow emptying again.

I'm now assuming the head gasket may be at fault bit don't want to go through a costly engine rebuild if not necessary so wanted to see what you guys thought? I have taken it to my local garage who I trust with all my previous cars but they won't touch it so have looked up reputable specialists in my area which is where I found prosport.

The bottom end of engine was rebuilt approx 40,000 miles ago for failed pistons which I have receipts for so the head gaskets were replaced once before but doesn't say the heads were skimmed.

Is there anything I have missed before going through with a costly head gasket repair? I am consideringdoing the job myself as a stock car driver I have experience rebuilding engines but never one of these has anyone else ever tried it? Is it do able? Obviously I would have the machine work done elsewhere.

Cheers Kyle

I think the first thing would be a sniff test and also a compression test just to make sure your diagnosis is correct.
If the head gasket has gone then I'd suggest you also get the big end bearings done at the same time, as they are notorious for going after a head gasket failure. The engine will be out anyway, so it'd be worth it for piece of mind.