Hi all,

I am completely stumped with my Fabia vRS. It has been a problem car ever since I bought it just under 2 years ago and to be honest, I just want rid of it. Since I have had it in terms of the water system, it has had a new radiator, thermostat (+housing), water pump, tank and cap. Just before my water pump failed, I was getting the very same issue I was having now - lots of pressure building up in the expansion tank setting the alarm off until eventually I spotted a leak underneath the car. The water pump and cambelt was replaced back in October.

I have taken it to a garage suspecting the head gasket but the sniff test has come back clear and no leaks found on the block test. It was setting the alarm off approximately every 2 weeks but now it is doing it every 1-2 days. Oddly it seems to be at a consistent distance. I have no signs of HGF and have been assured by the garage that the head is fine. It isn't overheating, drives fine and all the pipes are warm so the water is circulating. It is not losing water, just pushing the level right down, setting the alarm off but when I release the pressure it returns to the max level.

Has anyone got any ideas before I drive it into the wall for entertainment purposes?

When you took it for the block test, did you 'drive it like you stole it' just before the test. Sometimes a crack will only open up when the car is driven really hard and will pass a block test if driven normally

Worth just removing the thermostat for a test period; this will show if that is causing the problem. Often the small pin sticks if this is the problem just cut off the pin.

When you took it for the block test, did you 'drive it like you stole it' just before the test. Sometimes a crack will only open up when the car is driven really hard and will pass a block test if driven normally

No I didn't actually, it's only down the road. Although the garage may have taken it for a quick spin before doing it but I'm not sure.

Worth just removing the thermostat for a test period; this will show if that is causing the problem. Often the small pin sticks if this is the problem just cut off the pin.

Worth a shot definitely. Is it something that I could easily access and take out? I have no idea where it is :( I let the car warm up last night then 'drove it like I stole it' and the level was pressurised below minimum as soon as I got back - the alarm did not go off though.

One other point is that I did notice that while I just had it running on the drive for 10 mins with the coolant cap off, I did see steam coming out of the tank so it heated up quickly. Do you think the thermostat could be stuck shut?

Steam from the tank is normal. The coolant from the return pipe is always very hot and that is what you are seeing.

Coolant doesn't flow through the radiator until it is hot enough to open the thermostat. IIRC, it's fully open at 102°C and you will never get to that with the pressure cap off. You have to remember that it is a pressurised system where the coolant will not boil until it's much hotter than 100°C.