MK5 AXX | Thermostat bad?

[spiritdust]

Hi.
I was surprised that to replace water pump you need to do timing...
So... When I'm driving and outside it's -5°C with climate set to highest temp, my coolant temp. gauge stays around between 90 and 0... If I lower the heat and floor the car it goes up to 90°C, on warmer days it takes like 20min drive to reach 90°C, so is thermostat going out or it's normal for GTI's? Thanks

[LC5F]

Not 100% sure I follow what you are saying - a healthy car should sit at 90 all day long.
if you are asking for more cabin heat while it is cold - it will take longer for engine temp to heat up.

[colesey]

If you put your heating on full, then you are effectively increasing the size of the cooling capacity with the heater matrix. 20 mins to reach operating temperature suggests your thermostat needs replacing. Your fuel consumption on short journeys must be pretty bad.

[probedb]

If it gets to 90C and stays there it should be OK. The gauge isn't 100% accurate so it might say 90C on there but hasn't actually reached that temp yet. Pretty sure a knocked through precat will make it take longer to heat up as well since that's not holding heat in anymore. Mine isn't super quick but once it gets to 90C it stays there even driving at 70 in minus temps, whereas it used to drop when it was bust.