Low mpg

[Sprint311]

Hi.
I've got a 2008 sprinter 311cdi 110 000 miles and it started use 10-12% more fuel in same driving conditions. The wheels are running free.
Have you got any idea please?

 

[mersum1es]

Thermostat fail (what's engine temp?), blocked air filters, faulty MAF?

 

[Stratman]

Cars always use a bit more fuel in the winter, but it's very possible you need a new thermostat. It should be up around the 90C mark after five or ten miles and stay there. If the temperature fluctuates once it's hot the 'stat has definitely failed.

 

[thecolonel]

also consider checking air filter and fuel filters (the former, esp for water ingress which clogs the filter and will cause the engine to run richer).
Fuel filters become less efficient with age and may cause slight MPG issues but this is less likely.

Also, driving styles in the wet change so that could allow for 15% extra usage esp considering the colder ambient temps.

are you monitoring actual miles per tank as opposed to the mpg on the cluster?

 

[Sprint311]

Thank you to all.
Fuel, air and oil filters are nearly new.
Im monitoring every fill up since i have it. Just over a year.
I use to do 380 miles with 56 litre of diesel. Now just only 330 miles.