Hi all,

First post here (long time lurker though). I’ve made sure to search the forum for this already however all I can find is people querying the coolant level itself dropping, not the temperature.

I’ve got a 2015 Fiesta ecoboost (140 version). Now I’m probably just being overly cautious, but I’m weary that this car is notorious for coolant issues.

Whilst on my commute the other day I noticed the engine coolant temperature dropping down a bar, holding it for a few miles and climbing back up (the horror, I know) sometimes over 20 miles into the journey. It’s been happening every day since. I’ve made sure to check the coolant level after every trip and it’s definitely not losing any. I’ve not noticed any difference in performance, it’s also blowing hot air without any trouble. I also drive mainly motorway miles (if that’s of any use).

I know it’s been particularly cold the last few days, however it’s never done this in the 3 years I’ve had the car and even colder weather I’ve driven in.

Again I’m probably just being too cautious, but given the ecoboost’s reputation I would prefer to play it on the safe side.

So, something to worry about it? Am I being a flid? Has anyone else experienced this? Any feedback would be very much appreciated.

Thanks in advance.

Hello all, Hi JibeddyHibeddy same as you first post and(long time reader) I have also noticed the temperature doing the same thing on my 2016 Fiesta 1.5 diesel on a level road the temp drops one bar then start to climb any hills it goes up to two bars I have only had the car ten weeks but since the really cold weather the temp has been dropping, checked coolant no loss so I wouldn't be worried about it probably just the norm with the cold weather.

Regards, Rod.

I wouldn't compare diesel and Ecoboost engines. I got 125 bhp Ecoboost and I live in Finland. Only times when my engine doesn't get into 4 bars is when it's really cold outside (-20 to -30 degrees). And even then it gets there occasionally and then drops black to 3 bars depending on which gear I use. 

Maybe my engine has different thermostats suitable for cold climate or your engine has a faulty thermostat. I've seen a few cases where a thermostat has failed in an Ecoboost engine.

We have a small fleet of fords at work and they all do this exact thing.