2003 impreza 2.0gx over heating

Hi everyone i have a 2003 2.0gx auto had it a few days now and never had a problem with it but on a run it started to over heat
Its been fine round town even ticking over out side the school for half hour never goes over the third mark its just on a run.
I was thinking thermostat could it be anything else

Thermostat, coolant, head gasket?
They're the only things I can think of

dont think its head gasket as there is nothing else just it running warm for a little bit then it drops back down where its meant to be

Does it bother the engine at all?? i.e go into limp or holding back when accelerating?

holds back some times after its got warm.
the thing is its spot on in town just on a run

I had a nightmare with mine a few years back. Started as you ay yours is but just got worse over about 2 weeks to the point I avoided motorways and struggled to pull away from junctions.

I replaced everything like themo, pump, coolant etc 2 time served mechanics (Not clued up on imprezas, but brilliant mechanics either way) said it was the start of HG fail.

I/we had checked the radiator over looked in mint nick for the age of the car and seamed to flow fine. One member on a forum said bite the bullet and just replace the Rad, I did (against loads of peoples 'advice') and the car ran spot on after that. Still running as well 5 years later!

Not saying it is the Radiator but thought it would be worth while considering it. That's what fixed mine.

Through out the whole ball ache, I had not one fault code or engine warning light come on.

sounds the same NO lights on at all car runs great in town just not on a run.
over heated at durham services. topped water up then drove back to darlington got about 1 mile from the junction to darlington and started to get really warm but my foot down a bit and the temp started to drop all the time it doing that it never missed a beat.
changed the themo today been back out in it got up to stockton all ok started driving back and the temp started to raise
went the back way home and the car started to miss behave
its now parked on my drive cooling down.

if its not using any water then you have a problem with either water pump or radiator, if it is using water then its either a leak or headgaskets bud

its not using water its kicking it out the the expansion tank

mark78 wrote:

its not using water its kicking it out the the expansion tank

unfortuanatly thats what happens when head gaskets fail, the pressure in the cylinders seep through the gasket into the water jacket, this causes excessive pressure in coolant system and opens the valve in the rad cap, which then starts to fill/overflow the expansion bottle

when its running hot i have squeezed the top pipe and its not that bad

if i stay in town nothing happens even after ticking over for 1/2 hour out side the school

When mine was a sport i ad the same problem. Lot of people saying the head gasket etc . in the end it was my raidiator cap . uprated 1 .1,2bar from west auckland solved it for 8 pound. miye not be this im no expert mate but mite be worth a try ? Goodluck either way

just done the school run this morning and it ran lumpy till it warmed up.
on the way back got a bit warm.
just checked the radiator,

the top is red hot

the center of it is hot

the d/s is cool half way down and cold at the bottom

the p/s is the same

i'm now thinking more a blocked radiator,

what do you all think?

update on the over heating.
flushed the rad out on monday with some chemical and hose pipe
seemed a lot better after that
i was out in the car yesturday and got stuck in the traffic in town (snow )
i was in traffic for about 2 hours and not once did it over heat it got very warm but never hit the red.
it is looking more and more like its the radiator

do i change it or give it another flush

Change it ASAP or you'll end up fk ing it