C220cdi reduced economy

[hollyhocks]

Hi our 2002 C220 CDI seems to have lost about 10-15% of its average miles to the gallon, any ideas anyone.
Thanks

 

[joecash]

what's the temperature gauge reading it should read around 90C and hold steady once up to temp

 

[hollyhocks]

Hi no it seems to vary from around 65-75

 

[joecash]

change the thermostat - not that expensive - will pay for itself very quickly in fuel saved
common problem - quite a few threads on here

 

[t-dawg1]

change the thermostat - not that expensive - will pay for itself very quickly in fuel saved common problem - quite a few threads on here

+1 thermostat I had that issue on my old C220 and solved after I changed it

 

[Harlowcabbie]

Had same issue fuel economy suddenly very poor and engine ran colder than normal new stat and nice warm engine and back to great economy.

 

[rom1]

I have the same problem and am changing the termostat
£34.60 for stat with housing from Mercedes Leicester
£3.60 for gasket
I need to know how much and which type of anti freeze I need, from dealer it is £30 for 5 litres does anyone know where I can get it from a bit cheaper?

Had problem of dpf not regenerating and it's been cleaned now so I didn't want it geting blocked again think it was down to engine not getting hot enough temp has been 70- 80 but drops right down to 65 even after a 700 mile trip to Scotland and back only averaged 42 MPG. Highest it got was 85 but does not stay or rise

 

[hollyhocks]

Hi thanks for all your comments, why do you need to change both the thermostat and housing?

 

[rom1]

Hi thanks for all your comments, why do you need to change both the thermostat and housing?

Thats how it comes as a complete unit, in the housing with the stat and sensor,
I also thought I could just buy the stat but have not found one any where.

 

[ivandraganov]

The stat will make little or no difference on the mpg...

 

[hollyhocks]

Thanks for that, I will give it a try

 

[rom1]

The stat will make little or no difference on the mpg...

If the temp is not getting high enough the engine is running cold/warm and is not efficient, so why will the stat not make any difference?
Also regeneration takes place when temp is high enough so will this not help either?

 

[ivandraganov]

I've changed my stat without noticing improving in mpg figures,with the new stat takes to long to come to temperature too it's CDI for a reason....

 

[Harlowcabbie]

A failed stat will most definitely reduce fuel economy a diesel runs best when the engine is hot so a stat not allowing it to reach the correct operating temp will effect your mpg.

 

[joecash]

A failed stat will most definitely reduce fuel economy a diesel runs best when the engine is hot so a stat not allowing it to reach the correct operating temp will effect your mpg.

+1 spot on

 

[m2287]

How long should it take to warm up? today in rush hour traffic, it took me 45 mins to drive 17miles and it had only reached 80degrees, in my c220 cdi!!!

I then drove another 5 mins after my first stop and it went up to 90 degrees as there was no traffic, so I know it will reach temperature, it just takes a while!

 

[V12]

10mins should be enough no matter what kind of driving.

 

[BlackC55]

They do take sometime on a CDI as they are very thermally efficient.

 

[ivandraganov]

Fail stat will allow the normal temperature,the matter is that it's takes to long...For 5 mile commute you wouldn't notice at all...My Merc needs 20 min to reach 85'C.

 

[joecash]

multiple short journeys in a diesel where operating temperature is never reached is music to a garage owners ears -or put simply "cash in the bank"