I replaced the thermostat on my 2005 1.2 Fabia Mk1 (just the start itself, not the whole housing because I am both cheap and lazy). Somebody disturbed me at the moment it came off so I didn't get a photo of the order of the pieces. As per the attached photo there is the brass bit, a spring and a valve. I put it together in the way that made sense (brass bit in main housing, spring in cover and valve stem pushed into spring so that the face points to the flange in the main housing). Now it seems to be stuck open as the temp gauge only goes up to normal when stationary, when moving and air is hitting the rad it drops right down. Des anybody have an illustration of how it goes together? I can't find one on the Web. 

I don't think some of those illustrations are very helpful but it sounds like you got the order right (not sure from your description):

 

 

Was it very cheap? 

Edited 15 March, 20215 yr by Wino

Thanks, agreed it looks like my logic was right. I'll open it up again to see if anything is stuck. £11 delivered from ECP. 

👌

Either debris holding it from closing, or 'too cheap', I suspect.  (Edit: or damage to the sealing face of the main housing?)

 

 

I bought a genuine one (the one pictured) which was about £35 off ebay. Lasted 7 or 8 years until the rest of the engine died around it recently.   I expect they're even more than that now.  

 

Cheap one on at teh moment: NEW GENUINE AUDI VW SEAT SKODA 1.6 FSI COOLANT THERMOSTAT - 03C 121 110 A | eBay

Edited 15 March, 20215 yr by Wino

Before taking it apart again I gave it a few sharp taps with a rubber mallet to see if that freed anything. No immediate change, but after about 15 miles I noticed the gauge was up to normal, and there it has stayed. Still no heat through the vents, but I turned the knob clockwise in small increments and the heat started to come through and got warmer with each turn, so happy again.