andrew strasfogel wrote:
My 300TD has been getting progressively, steadily worsening fuel economy
over the last few years. It runs fine, there are no fuel leaks to speak of,
and I haven't changed my driving habits. I had been driving it in "2" at
Marshall's recommendation, but thought this might be causing the decline in
fuel economy so switched back to "D" around town.
Makes zero difference.
When I say the fuel economy s*cks, this means that whereas I used to drive
up to 380 miles before the reserve light came on, now it's exactly 100 miles
LOWER when I hit reserve (under 300 miles). This translates to 18 or 19 mpg.
I am beginning to feel ashamed that my DIESEL could fare so POORLY in fuel
consumption. Best I ever got was 27 on the highway but until a couple years
ago I faithfully averaged 22-24 during the non-winter seasons, mixed
driving.
I assume my problem is that the engine is running "rich". How would this be
addressed?
Thanks in advance,
Your engine is NOT running "rich." With diesels there really is NO such
thing (except at wide open "throttle" under full load - and then there
IS smoke). More fuel simply translates into the engine running faster -
UNTIL you use up all the air and then the engine smokes. If you are
using more fuel to go the same distance (and NOT smoking all the way)
you are either NOT measuring something correctly, OR doing more work, OR
the energy isn't being effectively transformed into motion OR the fuel
is leaking/being dumped somewhere - somehow. There really aren't any
more options.
How does chain stretch measure? More than 6 degrees and economy will
drop a little. When the thermostats in my cars stick open, fuel economy
drops - sometime by 20%. Engine needs to come from a cold start up to
85+ degrees C. (185 F) within several minutes of driving or the
thermostat is likely stuck open (at least a little) and fuel economy
WILL suffer (maybe a little or maybe a lot). Tire pressure below the top
end of the Mercedes recommendations can reduce fuel economy by 10-15%.
Improperly adjusted valves can reduce it a little.
Fuel leaking somewhere is the most common cause.
Marshall
--
Marshall Booth (who doesn't respond to unsigned questions)
"der Dieseling Doktor" [EMAIL PROTECTED]
'87 300TD 182Kmi, '84 190D 2.2 229Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5
turbo 237kmi
