Hello all, I've got an Octavia Diesel that is getting a bit hot on the way home from work. I'm guessing that the thermostat may need changing but I need some advice from you lot before I get the spanners out. I have had a brief look but the casing of it looks sealed to me. There are no nuts and bolts on show so how do I do it?

I may bre wrong here but if it's getting hot it could be the water pump.

Normally the thermo stat sticks open making it run cold.

Like say I may be wrong

I don't think a stuck CLOSED thermostat will give you a hot running level on the gauge, as I think the temperature sensor is on the radiator side of the thermostat which is why on a cold day the temperature stays low for ages, and them promptly rises to normal temperature once the thermostat opens. And as has been pointed out, by far the most common failure mode is to fail OPEN, and I wouldn't be surprised if this was a deliberate failsafe feature.

I'd be inclined to agree with it being the waterpump. It's much less common for them to go that it used to be on the old 1.8Ts, but never say never. The only other thing it might be is the sensor itself. Showing my age a bit here, but the best way to check (other than a fault code scan) would to turn the heater up to maximum heat, and the fan up to full, and see if this helps as you will be adding the heater matrix as well as the radiator to the available heat exchange area. If the temperature starts to go down again (even just a little bit), then the sensor is probably working correctly and the pump's gone.

If it HAS gone, you may as well get a new cambelt put on.

If you're at all worried about the head gasket, this guide on ebay is actually pretty good, if you can get past it all being typed in capitals! :(

http://reviews.ebay.co.uk/HOW-TO-TEST-FOR-A-FAILED-HEAD-GASKET_W0QQugidZ10000000001891247

I don't think a stuck CLOSED thermostat will give you a hot running level on the gauge, as I think the temperature sensor is on the radiator side of the thermostat which is why on a cold day the temperature stays low for ages, and them promptly rises to normal temperature once the thermostat opens. And as has been pointed out, by far the most common failure mode is to fail OPEN, and I wouldn't be surprised if this was a deliberate failsafe feature.

I'd be inclined to agree with it being the waterpump. It's much less common for them to go that it used to be on the old 1.8Ts, but never say never. The only other thing it might be is the sensor itself. Showing my age a bit here, but the best way to check (other than a fault code scan) would to turn the heater up to maximum heat, and the fan up to full, and see if this helps as you will be adding the heater matrix as well as the radiator to the available heat exchange area. If the temperature starts to go down again (even just a little bit), then the sensor is probably working correctly and the pump's gone.

If it HAS gone, you may as well get a new cambelt put on.

If you're at all worried about the head gasket, this guide on ebay is actually pretty good, if you can get past it all being typed in capitals! :(

http://reviews.ebay.co.uk/HOW-TO-TEST-FOR-A-FAILED-HEAD-GASKET_W0QQugidZ10000000001891247