Michael_W Posted May 22, 2018 Share Posted May 22, 2018 Im sure you will all have seen a simlar post to this before but i really need some help. I have a 2006 WRX 2.5L wagon with 74k miles and recently i have been having an issue with the engine getting hot. I fitted a new thermostat and did a coolant flush, filling very slowly through the turbo pipe and making sure that there was no air trapped in the system. The car will idle and stay at the optimum temperature and even cool the engine if hold it at 3500 rpm to get the temperature to rise to 98 degrees, and it will drive and maintain temperature but as soon as i drive it hard and the turbo spools up the temperature starts to rise. So many people i have spoken to have said it will be the head gasket but the oil and coolant are clean, there is no chalk on the radiator cap, no milkshake on the dip stick and no white smoke from the exhaust Each time i have burped the system and seem to have everything settled it drives for a day or two with no issues but then gets hot when driven hard. When the engine gets hot the fans run cold inside the car so it would appear it either still has air in the system or its drawing air in to the cooling system Does anyone have any ideas what could be causing this? Quote Link to comment Share on other sites More sharing options...
Greenmamba Posted May 22, 2018 Share Posted May 22, 2018 Firstly did you fit a genuine Subaru thermostat or a generic? Quote Link to comment Share on other sites More sharing options...
Michael_W Posted May 22, 2018 Author Share Posted May 22, 2018 Quote I fitted a genuine Subaru Thermostat and seal which i bought from Cotton Competition Quote Link to comment Share on other sites More sharing options...
Greenmamba Posted May 22, 2018 Share Posted May 22, 2018 OK. Couple more questions. When you say the fans run cold, confirm that means the heater/air con? What about the radiator fans - do they work fine? When you burped it, was it on the level or nose-high? When filling the coolant, was the heater (in the car) working? Any bubbles in the coolant when the engines running? Quote Link to comment Share on other sites More sharing options...
Michael_W Posted May 23, 2018 Author Share Posted May 23, 2018 The fans are the heaters in the car . They blow cold when the engine temp rises above normal. The heater was set to hot when draoming, filling an burping. Radiator fans are working correctly and kick in to cook the engine. Car was level when filling and burping but also tried burping at the top of my steep drive way after doing it level. There was bubbles while burping it. And after engine gets too hot and i let it cool to cold there are still bubbles in the coolant at the header tank. I've just been for a ten minute easy drive and the engine temp is perfect, it only gets too hot when it's driven quickly Quote Link to comment Share on other sites More sharing options...
Greenmamba Posted May 23, 2018 Share Posted May 23, 2018 Sounds like you may be looking at a head gasket, particularly the mention of bubbles in the header. Fans blowing cold when it's overheating could point to a blocked heater matrix. HAve you managed to flush the heater matrix, both forwards and reverse? Checked the radiator is not blocked with debris, leaves etc. Quote Link to comment Share on other sites More sharing options...
Michael_W Posted May 23, 2018 Author Share Posted May 23, 2018 How would I flush the heater matrix ? I just drained the coolants via the radiator I haven't checked the ratiator for any blockages, I'm guessing to do that I would just need to remove it and blast water through it and give it s good shake ? The fans are the heaters in the car . They blow cold when the engine temp rises above normal. The heater was set to hot when draoming, filling an burping. Radiator fans are working correctly and kick in to cook the engine. Car was level when filling and burping but also tried burping at the top of my steep drive way after doing it level. There was bubbles while burping it. And after engine gets too hot and i let it cool to cold there are still bubbles in the coolant at the header tank. I've just been for a ten minute easy drive and the engine temp is perfect, it only gets too hot when it's driven quickly Quote Link to comment Share on other sites More sharing options...
Greenmamba Posted May 23, 2018 Share Posted May 23, 2018 Flushing the heater matrix involves removing the two heater (supply and return) hoses/pipes - black rubber about 25mm diameter, usually on the passenger side, engine side of the firewall. With both disconnected, insert hose and flush till the other side pipe/outlet runs clear. Reverse and repeat. Basically, you're flushing water not through the engine, but through the heater matrix built into the dashboard. Does the header tank bubble with the engine running? Does it lose coolant when it overheats? Quote Link to comment Share on other sites More sharing options...
Michael_W Posted May 23, 2018 Author Share Posted May 23, 2018 Thanks. I give this a try From cold when I open the header tank there are a few bubbles and I get more when I squeeze the radiator pipes but they soon stop. I've never seen bubbles in the overflow It's not losing coolant but when it gets hot the overflow tank is usually close to overflowing but when the car cools it's closer to empty. I always makes sure it's at the correct level when I start from cold and if the engine doesn't get too hot the level remains the same Quote Link to comment Share on other sites More sharing options...
stuartie Posted May 23, 2018 Share Posted May 23, 2018 I agree with @Greenmamba about flushing the heater matrix and taking the rad out and flushing that aswell, when i bought my scoob one of the first things i done was flush the coolant system out as the coolant in the header tank was a rusty colour and when i stuck a hose on the matrix pipes the amount of s**t that came out was unreal and same with the rad, so i would try all of that before going down the headgasket route, also they are an absolute pita to bleed 😉👍 Quote Link to comment Share on other sites More sharing options...
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