Legacy 250t overheating

[loganbrooks]

Hi, we have a 250t Legacy 2000 with 240,000km on it, and recently it has started overheating. Before you ask, yes we have done a head gasket check on it by using the carbon detector for the radiator, so far that has not showed any results of carbon and there are no bubbles in the coolant, not ruling it out but it appears to not be the head gasket.

Recently the top tank split, which we thought was due to age, so it was replaced and the radiator cleaned etc, and used a new radiator cap. 1000km later it overheated and all the coolant flowed into the expansion chamber/storage where it was boiling. It then emptied itself automatically and after putting tiny drops of water in the radiator was able to drive home without it overheating again, 30km. Since then the thermostat has been replaced with a genuine subaru one, and the radiator cap changed back to the original. Today it overheated again 60km into its journey(if it helps was doing 100kmph for 30mins then came into 50kmph zone where it overheated), when opening the radiator cap coolant (approx half a litre) gushed out, while reasonably hot, the coolant tank this time was at its normal level (a bit over he full mark). Then filled it back up with water (in the radiator) and have done 120km since and the temp hasnt changed. This has become unreliable to use, and it seems like its a ticking time bomb till it next does it. Has anyone ever expereinced this, or has any advice?

[Wheelbuilder_25]

I would check on the heater core and coolant pipe for leaks, and for an air pocket in the cooling system.

 

Did you use replace the thermostat with a Subaru one ? Some aftermarket ones don't flow well.

 

The temp spike after slowing down sure sounds like head gasket leaking between combustion and coolant, so I think I'd still check on that regularly. 2000's weren't known for that particular type of leak, but stuff happens.