thermostat?

[evdok]

The workhorse has finally started to complain about its health after 155,000mls! its a 1996 VW polo 1.6 petrol & on frosty mornings the temp Gage moves slightly and stays there even after 20mile trip, the heating is still working but not as hot, there is plenty of anti freeze so am i wright in assuming its the thermostat?

 

[Bazzle]

Probably.
Polo forums here
http://www.google.com.au/search?hl=en&q=vw+polo+forums&btnG=Google+Search&meta=

Bazzle

 

[Ted]

Almost certainly - but also check coolant level.
Way to test
Start car & leave running for a few minutes.
Feel the top hose - it should be cold.
If it is warm the stat is probably stuck open.

What should happen is the hose should stay cold until temp gauge shows engine is up to temperature, then very quickly get hat as the stat opens.