Over heating trouble

[karls3abo]

I have a Agu recently changed the thermostat as it was not heating up, along with the temp sender,

A couple weeks later it over heated, garge told me it was probably the heater matrix blocked up, so they flushed it with no luck, I got it home took the thermostat off to test it as it was a cheap one off eBay, then realised it was broken, the piston inside the spring, had come out of its hole so it was not opening.

Changed it for one from the auto factors, as vw wanted £25 just for the stat. And filled it bàck up with coolant. Now it is doing the same as before, it over heats with no hot air coming through the vents.... I have had a lot off air come through the heater pipes and can feel it bubbling as I work the air locks through from the top radiator hose. The hose coming off from the thermostat doesn't get hot. But I am sure there is an air lock there. And that the thermostat is open but the air lock won't let the water through. The reason I think this is because when I push that pipe down it seems to fill with hot water where my hand is but go no further.. Is there a sure fire way of bleeding the cooling system as I spent two hours trying but with seems like no progress. I am leaving it over night with the tank cap off to see if it drops.

Any help would be muchly appreciated. Or if anyone has had anything similar happen with there's.....

[Ludford]

I was having trouble with an Impreza overheating before. Matrix was leaking so I bypassed the whole thing all together. Still have overheating issues. Had the whole thing flushed twice and still got them. Then I was informed that a heater matrix failing is sign of a blown head gasket.

If you're getting no heat through the vents the matrix might have failed.

[navmk4gti]

Could be you have put a cheapy thermostat in again. Amount you have just spent on two you could have got genuine one

Is the front top coolant pipe ( one closest to the front of the car) cold then?? And bottom pipe is warm as you said? Get genuine stuff and change temp sender while you at it

[mattkh]

Hi
Have you run the engine yet, under strict observation, while the cap is off ?

[karls3abo]

I have out a new temp sender in and also the top radiator hose is too hot to touch and the bottom hose from the radiator to the thermostat is cold. Also I am sure the thermostat is opening as when I squeeze that hose I can hear the water going back through the engine block.

I think te head gasket has been bordering on going for a while and the dodgy thermostat had just tipped it over the edge. I have had white smoke for the last month or so and the whole cooling system pressurises. Even with the expansion cap off.

[harlemex]

I think this is a classic case of you have answered your own question.  Take it to a garage and ask them to do the gas detection in coolant test to confirm headgasket shouldnt cost much as its a five minute test. 

[karls3abo]

Hmm been pondering over it for a few days now. And ye I will se about doing that. Would save a lot of work if they can tell me by testing.