Engine temp and mpg issue

[noelmarc]

Hi Guys

Got a weird problem with my 2004 c220 cdi. The car operates at 60 degrees most of the time which i put down to a faulty thermostat but never got round to changing.

Since the car had a service A occasionaly the temp will rise to 80 ish but here is the weird part...... i lose 8-10 mpg when the temp rises.

i do alot of miles so this can be a bit of a pain, does anyone have any idea why i would lose mpg when it warms to its proper temp?

Also why it rises randomly but mostly operates at 60 degrees.

Cheers

Marc

 

[Troon]

Overfuelling to try to get the temperature up? (wild guess)

I'd suggest getting round to changing the 'stat and then see what's happening.

 

[Dichtung]

Faulty temperature indicator?

 

[noelmarc]

Overfuelling to try to get the temperature up? (wild guess)

I'd suggest getting round to changing the 'stat and then see what's happening.

i thought that might cause a lower mpg when running 'cold' perhaps a faulty reading as above. Hope its not over heating

with cruise on at 65mph it will do 54mpg over 20 miles but that can drop to 46 mpg on same run when temp needle shows 80 degrees.

Maybe i should do the stat but worried i get the lower mpg all the time