I've been running B100 and B50 biodiesel along with veggie oil (from my grease tank) in my '82 300D and have been getting TERRIBLE fuel mileage no matter what blend of anything that's in the tank. Nothings leaking out of the bottom when parked and ideling. Does anybody have an ideal of what's going on?

so how bad is it?

and have you checked your odo against the mile markers?

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I'm thinking around 10mpg, if that. But I have no way to check since the speedo doesn't work, typical. Most of my trips are just around town and to class, and when my veggie tank gets warm I flip over. But even with those small trips I'm using WAY more fuel than I should be. It wasn't always like this either, only in the last few weeks.

I know the air filter is clean and fresh!

Any excessive smoke?

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1976 BMW 2002- 100k
1995 BMW 325i 175k
1984 Mercedes Benz 300D Turbo Diesel- 270,000 mi

1981 Mercedes Benz 240D- Estimated 300,000+ mi Returned to the earth

Fuel leaks from old rubber lines?

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

Short stop and go trips will result in lower mpg. Also, biodiesel has a slightly lower energy content than regular diesel fuel, so you'll get slightly lower fuel mileage.

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

Do you know that your return lines - one for diesel and another for veggie - are going to their respective places? Two-tank Benz WVO conversions have to modify or replace the banjo bolt atop the stock spin-on filter to avoid cross-contamination of fuel. I suspect that your diesel is returning to the veggie tank ... which could be really messy really fast.

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1983 300SD, Silver/Blue, 230+K (rebuilt at 196K)

My return lines are definitly going to the right places, i've already dealt with that headache, and the banjo bolt was filled with JB weld when i did the switchover.

No excessive smoke. The benz runs great, just drinks biodiesel.

I changed the air filter 3 or 4 days ago (it seems like there was a lot of oil in it)

No leaking when i'm ideling. And most of my hoses where changed when I installed the second tank. Is there a rubber hose running from the factory tank to the metal lines that go under the car I should consider changing? The lines have been replaced in the engine compartment.

And I understand that short trips = lower fuel mileage, but I just drove to North Carolina and back this weekend and I really went through a veggie tank quick. Then when I switched to biodiesel it seemed to go through that quick as well. Luckily I brought 20 extra gallons of filtered oil to get me through the trip. I would have hated myself if I would have had to fill up on petro-diesel only to burn through it in 150 miles.

hmmm, maybe you have a hole in your return line(s)... it would not leak when parked, but only when theres pressure in the return line... ie when the IP is really pumpin'

besides that, I can only think of the normal stuff.. dragging brakes, underinflated tires etc.

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Cheers,
Robert

Have you checked the crankcase oil level lately?

Any oil in your coolant?

And yes, there are two short rubber lines from the tank to the metal lines under the car. One is supply, the other either return or vent (I can't remember).

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1983 300SD, Silver/Blue, 230+K (rebuilt at 196K)

I think no harm would come from starting the car or prefferable after a normal use just to hold the throttle linkage at about a third throttle for a few minutes and move car to examine for anything on ground. One more same test at about 1/2 throttle if engine does not seem to be too fast and check again. If you are as rich as you think you are I would almost expect heavy tailpipe emmisions would be present as well as you could probably not burn that much fuel cleanly. Run the tailpipe smoke emmision test with straight diesel. If no visable smoke the engine is likely not your problem. There then is only one thing left and that being a leak somewhere and it is more than a seep. Binding brakes of course should be checked by you first feeling the temperature of each wheel after a decent run before the above. All wheels should be the same temperature and coast to a stop to check them.

Does the power of the engine seem normal? When did you last get an alignment, change the fuel filters, and change the transmission filter? Check your parking brake to see if its screwed up and the brakes are rubbing.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png

First and foremost, you don't seem to have a clue as to what your mileage is. What difference does it make if it is good or bad if you don't know what it is? Get a clue! No speedometer is no excuse. Many of them are wrong anyway. Fill it up at service on the Interstate and watch your highway miles. Go about 50 miles, turn around and add in your return miles and fill it up again and you will know what mileage you are getting. It's simple and can be done in a leisurely 2 hours. It will probably cost you 4 gallons of fuel.

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Yup, my mileage on B100 seems to suck too. But at $0.70 a gallon, and the car in good operating condition with no fuel leaks, it's cheap enough.

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'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg