Car not getting to tenp

[Duravibe]

I just replaced the thermostat and water pump and now weird stuff is happening, i just drove 15 minutes going between 95kmph and 60 kmph and it barley made it past the 50° mark but on the return trip it wasnt 3 minutes the car was up to temp, should this be of any concern to me?

[Caretaker]

assuming you didn't put the new thermostat in backwards, did you "burp" the system after replacing all of the coolant? Sounds like there is air in the line. I know some cars, like the Fit, can be a pain to get all the air out. It normally takes a couple of days of removing the cap and topping the coolant off until it is full.

[jolt]

That is why they make these funnels to get the air out:

https://www.youtube.com/watch?v=ma7wI2QXhEg

Bleeding air out of system:

https://www.youtube.com/watch?v=gcCkGiaWN-I