Hei

Due to the fackt that out side temperatures are rising and now daily temp. is plus 12, my b14 (cvt) wants to boil.
Problem is then when car idle´s at neutral or like yesterday road was very crap so had to drive about 800m with 15km/h.
Engine temp. went high the temperature red light didn´t flash yet but were quite close.When got normal speed up then the engine cooled down and every thing was fine.
Don´t think that is normal?

belt is old and quite wear-but don´t slip,have a new one but haven´t managed to fit it.
coolant is changed and radiator is fine to,don´t think is stuck too.
water pump doesn´t make sound,so should be ok ?
termostat is working.

Any ides?
K.

Does the radiator fan work? It should go on when the coolant reaches a certain temperature

Yes fan is working.
Will do the radiator flush, may by it is stuck.

While you're at it get a new thermostat, maybe it doesn't work properly anymore

What sort of condition is the radiator in?
If there are a load of missing mesh fins in the rad then it would be better to get it replaced.

Is your expansion tank cap the correct pressure rating?

Fan works, thermostat works, car only cools down when driving at speedz - water pump is worn out