Impreza Turbo - overheating/blowing out coolant

[rx_sideways]

Hi all

Scoob was running perfectly yesterday, not pushing hard or anything... then when I was parking up it suddenly dumped a load of coolant from the top radiator pipe union. We let it cool down, tightened the union, topped up with tap water and drove home. The temperature was a bit erratic, but not overheating. Parked at Ramsey for 5 mins to grab some coolant, set off again and the union blew again and the temperature rocketed again.

So - topped up and nursed it the last couple of miles home.

Doesn't seem to be any oil/water contamination, so hoping not head gasket... maybe thermostat sticking? I'm going to pull that out today and test it, but in the meantime anyone with more experience of Scoob's got any ideas?

Also - if I get really stuck - any recommendations on good Scooby mechanics on the IOM? Thanks!

[Pugguy]

If it s not a worn/loose union then it certainly sounds like the cylinders are pressurising the coolant...
The first thing to do is pressure test the coolant system (all good garages will have a pressure tester)... and keep your fingers crossed!

[tree]

if its just overheating when parked/ slow moving as the picture i have painted then water pump?

if its just erratic when driving then there may be sufficeitn airflow to the rad to keep the water cool.

but yeah as Jono says pressure test is the first point of call.

[rx_sideways]

Whipped out the thermostat this arvo and checked it - it opened, but very slowly and only when in completely boiling water. So I've reassembled everything without the thermostat, left it idling on the drive for 30 mins to get up to temperature. Taken it into Ramsey, pootled around at slow speed, then ragged it up the hill - temp has stayed at or below normal at all times and its not blown out any more coolant - I'm thinking that the thermostat was just toast.

We'll run it around for a week as is and see what happens. Keep your fingers crossed for me!?!

[privatebill]

also make sure you don't have an airlock somewhere