I'm started on my third fill up with B-20 biodiesel. While the engine has never run so quiet and smooth, the fuel economy has dropped!

With dino and a little Power Services added, I had been getting 30 mpg quite consistently. But now as I've burned two tank fulls of B-20, my mpg's have dropped to 24.2, the lowest mpg I've ever seen with this car!

Anyone have any comments?

BB

ODD......I average about 20-23 in heavily city weighted driving....(over 50% stop and go) and thats on a W123........a car that naturally gets worse milage than yours. ANd thats with B20.

Perhaps you have fiilters starting to clog and you are driving it harder as a result.......B20 has strong detergent characteristics.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

In one way I hope it's the B-20, if not, I may have other issues such as timing chain stretch, or something else. Would a clogged fuel filter contribute to poor mpg's?

I run BD all the time, never affects mileage either way.

__________________
Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

Well from personal experience it does effect power......that in turn has you driving harder......that does effect your milage as you are into it harder for far longer......

How long has it been since you replaced the filters......I am asking this as it occurred in a fairly short period of time.....Timing chain stretch would takes 10s of thousands of miles to happen.....and the fact its running smooth tels me its not likely an injection issue.

THe canister filter is likely the one plugged if the prefilter is clear....prepair for both however....I think the B20 has loosened crud and clogged them.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

I changed the secondary canister filter late last fall. I just bought all new filters, air, both fuel filters, oil, and I have had planned to change all when I come up to 5k, another 1000 miles or so. I thought also that I'd wait and let the old fuel filter in there now pick up anything the B-20 has loosened up from the tank, lines, etc, before putting the new filter in.

On another note, I did notice a slight drop before the B-20, but had to do with dragging a left front brake pad with a seizing caliper, but that has been fixed.

i wouldn't think the b20 is the culprit. i am going on the idea that you are getting d2 40c with b20 so maybe it is up to 45c. (i don't know how to estimate that). were you using 40c with a full container of power service? what do you estimate the c rating of your old blending?

the wifes 240 gets a combined 25mpg so hwy cruising would be higher.

__________________
currently
[1981 300 td tdidi 165500 dark brown/palamino-Brownie-mine-3k miles of ownership
1983 240d 162+++ Anthricite grey w/ henna red interior and hella lights-wifes car-Red

the above two cars are for sale
and can be seen on the cars for sale thread here. pix also available.


240d-144+ Manilla Yellow w/ palmino interior-greasecar kit-Blondie-the college kids car

23" gt 21 speed still on original tires-still got the nubs
21" khs tandem

I have not seen a drop in mileage with B20 and I've been running it for a couple months now in the '81 300D. I did just recently go with 205 70 14 tires (versus the 195) and although my odo indication reads about 10% lower, I'm going more days on the fuel gauge and that is the one that matters anymore.

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Jim

I have noticed a significant loss of mpg. Normally I get over 600 per full tank and with this one station I get around 550. Switched and got over 600, switched back got around 550. Did the test a couple of times and am convinced that the D2 at this shop is not the greatest. What does this mean? Well, lets say the shop you got the B20 from is getting the diesel from the same supplier or the same quality as i did at this one stop, mixes 4 parts of it with 1 part of B100 to get your B20, it could be the bad diesel part that is screwing up your mpg. Why don't you do what I did and get it from the usual source when your tank is empty and test it out. Of course, I would change the filters if they are dirty or even suspect, as in this case.

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

I did all filters yesterday including last Octobers air filter and found it to be extremely filthy including sand that had collected in the canister. Lots of sand put on the roads this past winter and may be the cause for poor fuel economy.

Too early to tell yet, I'm only 100 mi into the last fill of B-20 at $2.80 a gallon. Regular diesel here is $2.42 and reg gasoline is $2.35 ...........BB

Well keep your fingers crossed...it took a few tankfulls before some crud let loose and clogged my filter....I see more in the fresh prefilter...and have been running Biobor in every tankfull to be sure its crud and not the little beasties.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

BHD, what does the clog stuff look like in the pre-filter?

We have been putting Biobore or Biocide, in the the boat's tank for years and still have to change out the Racor filters at least once a year. The stuff looks like thick black tar.

I honestly never cut it open to see.....I was a long way from home in a parts store parking lot......but what I see now is tiny black flecks.......but then I recently had the rubber return line under the car turn quite porous and leak a quart a day....also my injector return lines were leaking and I just replaced them so that may have been the source of the flecks...

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche