hi. i have ordered a thermostat housing complete with a new thermostat installed. i also have coming a  new temp sender to fit at the same time. my question is..... do i need to use any kind of sealant where the housing mates to the engine ? thanks

Don't think so, just clean the area very well..............you could use something like blue hymolar, or the equivalent for cooling systems.......can't remember at the moment, it's a few years ago since I did my mates one......

It mates to the engine using an O-ring not a gasket, so you shouldn't use sealer.

Above^^^^^^..........

yeah realised when i opened the box. system flushed, mating faces cleaned, all back together inside an hour. checked level and took it for a spin. temp reaches smack in the middle and stays there. seems to run better too.

the old stat had collapsed and a big rubber o ring was hanging out into the top hose. 

proper job.

 jobs still to do:

remove engine cover and throw away ( oil cap and seal on its way)

new aux belt ( i'll do this after i get rid of the engine cover)

locate the creaking bush / bushes and replace.

i have to say i'm well pleased with this fabia. drives better than the wife's 03 polo