Hello colleagues,

1 month ago I changed my thermostat as the engine temperature was no longer reaching 90 degrees. Today, I was driving to work and the temperature reached 90 degrees only after 25 mins of normal driving(There are -8degrees outside) Then, I let the engine to idle for 5min and the temperature decreased to 80degrees and the idling rpm increase from 700 to 1000rpm.

For me this does not seem normal. It looks to me that the new thermostat needs again replacement, what do you guys think? How is the temperature in you vehicles acting?

So far no answer from my local shop that did the replacement.

I'm also having this issue but not on a new one! I drove the other day in 8°c for half an hour and still didn't reach 70 on the temp gauge and when I stopped in a que with engine idling it dropped to 50! Not sure if I can replace it myself or not?

On 20/01/2026 at 07:52, Racataian said:

Hello colleagues,

1 month ago I changed my thermostat as the engine temperature was no longer reaching 90 degrees. Today, I was driving to work and the temperature reached 90 degrees only after 25 mins of normal driving(There are -8degrees outside) Then, I let the engine to idle for 5min and the temperature decreased to 80degrees and the idling rpm increase from 700 to 1000rpm.

For me this does not seem normal. It looks to me that the new thermostat needs again replacement, what do you guys think? How is the temperature in you vehicles acting?

So far no answer from my local shop that did the replacement.

Which thermostat did you change?

12 hours ago, Jaynet62 said:

I'm also having this issue but not on a new one! I drove the other day in 8°c for half an hour and still didn't reach 70 on the temp gauge and when I stopped in a que with engine idling it dropped to 50! Not sure if I can replace it myself or not?

it is not very easy for a DIY mechanic, at least for me, at this time of year and without an elevator, I would not do it.

10 minutes ago, persimmontom said:

Which thermostat did you change?

unfortunately the repair shop did not mention on the invoice and I did not ask. I know it is not OEM

At winter time its normal that temp goes down at idle or low speed city driving. These cant keep temp 90 at idle. But if it dropped immediately not about after 2-5min then there is something.

5 hours ago, Karpov said:

At winter time its normal that temp goes down at idle or low speed city driving. These cant keep temp 90 at idle. But if it dropped immediately not about after 2-5min then there is something.

at idle, the temp dropped in about 5mins to just bellow 80degrees and stayed there. The rpm increased to 1krpm but the temp stayed stable at 80 degrees. I don't remember notice-ing this before thermostat replacement, it always stayed constant at 90 even at idle and even at -some degrees. An I can accept it is normal to decrease some degrees but the fact that the rpm increased this means it got into an mode where the functionality is not ideal so I tend to think the thermostat hysteresis is not made for this car, it's too large

Edited 21 January21 Jan by Racataian

Yes rpm gain is not normal but sounds otherwise normal