Failing thermostat?

[Patrick Bateman]

Haven't driven the car for a couple of weeks due to being on holiday and tonight noticed with the recent temperature drop that the water temperature took noticeably far longer to get up to operating level (still hadn't got there after a solid 10 minutes driving). I suspect the previously milder weather has disguised this- to me it's the typical sign of a failing thermostat, have also had a suspicion my fuel economy has been slightly worse for a while now.

Are there any other considerations here? Coolant temperature sensor? As well replacing both since they're likely original regardless?

2 points to note-

Back in the summer there was one day where I noticed the water temperature needle on the gauge fluctuating down the way. This was when the car had already been running for a good 30/4 mins. When I accelerated fairly hard the needle would rise up to the horizontal then dip down again slightly when backing off. This only ever happened on the one day.

Tonight there also seemed to be a major hesitation when trying to get up to 60mph just as I was approaching 3000rpm, eventually disappeared after backing off a handful of times. Not sure if it would be related at all as I've never encountered this before, will need to drive it again tomorrow and see if there's any change.

 

[Amos91]

It will take longer to warm up due to the weather regardless. Needle should however rise to the middle and stick there. If there are some small fluctuations I'd change it with a genuine item.

 

[Patrick Bateman]

It will take longer to warm up due to the weather regardless. Needle should however rise to the middle and stick there. If there are some small fluctuations I'd change it with a genuine item.

Yes but what I mean is on the 10 minute drive I was talking about, it would always get to operating temperature on the gauge within that journey, it was still clearly short in this instance.

 

[Patrick Bateman]

Appeared to be issue free today and was up to temperature quickly. I'll keep an eye on how it performs.

 

[Krarl]

Clean the coolant temp sensor, they get scaly and sometimes dont read properly. My car ran like a bag of spanners because it was coated with a tiny bit of crud

 

[Patrick Bateman]

Thanks, I shall keep that in mind if I get a re-occurrence.

It's been totally fine since posting this. Wonder how much it sitting doing nothing for 2 weeks contributed.

 

[MLB]

Mine fluctuated every now and then on the motorway, nothing major but would get (sort of) up to temperature within a reasonable amount of time and still looked like this:

If you've got basic tools I'd say for the money of a thermostat and some coolant get it changed if it hasn't been changed recently.