The 2.7 TDV6 engine in my car (it is a 2005 D3 actually) is not heating enough.
It touches 77° C maximum, even after changing the thermostat.
Any suggestions on how to solve this problem are very welcome, since the fuel consumption has gone up by about 10-15% since this problem first occured.

Where are you reading the 77c from ? the dash ?

May be you have a lazy temp sensor , if so this may make the ecu think the engine is colder than it actualy is and then add fuel to match.

This will kill the consumption because it is running on choke so to speek.

simple test , run the car so you think it is hot at can be , EG 77c on the dash.
Then use digital thermometer and measure water temprature manualy.
If you have 2 different readings then the car water temp sensor may be faulty and out of scale.

Regards Pete Follow Us On Twitter @bellautos

Thanks Pete,

The initial 77° C I've mentioned comes from a digital thermometer already. On the dash, I only noticed that the indicator doesn't go up to the level it always was before. (it doesn't mention the actual degrees)
So I'm pretty convinced already that the reading on the dashboard meter and on the thermometer are the same.
On the other hand, I might try the temp sensor, seems to be the logic next step in trying to find the solution.
Rgds.