10 to 20 percent biodiesel - PeachParts Mercedes-Benz Forum

smartin · #1 02-28-2003, 10:51 AM

85 300TDT (120K miles) - As for the usage of (say) 10 to 20 percent biodiesel and 90 to 80 percent regular diesel - do I need to worry about rubber parts/seals? Just read an article about a guy using straight diesel (82 240) - (unless I missed something) he changed filters at first - but nothing else?

McRoth · #2 02-28-2003, 11:18 AM

Nope, nothing to worry about with B20 or so. I used B100 for a couple of months last summer with no problems. they sell B20 retail because there are no problems with the rubber parts.

Joe Blowe · #3 02-28-2003, 11:25 AM

biodiesel, even at 10% or 20% concentrations, will eventually break down all of our old rubber fuel system parts. not to mention the solvent action of biodiesel will release any old crud in your tank and send it on down to the fuel filters...

at a minimum, look into Viton fuel lines, monitor other seals and gaskets, and replace your fuel filters often (not sure of interval) after running biodiesel.

check my collection of biodiesel links for further information.

Joe Blowe · #4 02-28-2003, 11:34 AM

Quote:

Originally posted by McRoth
Nope, nothing to worry about with B20 or so. I used B100 for a couple of months last summer with no problems. they sell B20 retail because there are no problems with the rubber parts.

http://journeytoforever.org/biodiesel_vehicle.html

"Biodiesel, being an organic substance, tends to be absorbed by natural rubber -- after a month or so exposure, the rubber swells and rots. This applies to all ratios of biodiesel additive to petrodiesel. A tank or two to try it out will do no harm, if ULSD or standard diesel fuel is used thereafter."

McRoth · #5 02-28-2003, 11:57 AM

This is from a fact sheef from the National Biodiesel Board:
"The school district
has used B20
since 1998 in half
of its fleet. Bus
drivers have
found that the
use of B20 is
transparent,
requiring no
engine modifications,
no special
infrastructure,
and no fuel-related
maintenance
problems. DOE
and the State of New Jersey provided funding to
install a B20 fueling tank. “Expanding the use of
biodiesel to a portion of the state’s diesel-powered
fleet is consistent with New Jersey’s overall efforts
to promote advanced fuel technology” said
Transportation Commissioner and NJ Transit
Chairman James Weinstein."
http://www.afdc.doe.gov/pdfs/Biodiesel_fs.pdf

Here's another one from the NBB:
"Myth: Biodiesel causes filters to plug.
Fact: Biodiesel can be operated in any diesel engine with little or no modification to
the engine or the fuel system. Pure biodiesel (B100) has a solvent effect, which may
release deposits accumulated on tank walls and pipes from previous diesel fuel use.
With high blends of biodiesel, the release of deposits may clog filters initially and
precautions should be taken to replace fuel filters until the petroleum build-up is
eliminated. This issue is less prevalent with B20 blends, and there is no evidence that
lower-blend levels such as B2 have caused filters to plug."
http://www.biodiesel.org/pdf_files/Myths_Facts.PDF

From the same article:
"Myth: Biodiesel causes degradation of engine gaskets and seals.
Fact: The recent switch to low-sulfur diesel fuel has caused most Original Equipment
Manufacturers (OEMs) to switch to components that are also suitable for use with
biodiesel. In general, biodiesel used in pure form can soften and degrade certain types
of elastomers and natural rubber compounds over time. Using high percent blends can
impact fuel system components (primarily fuel hoses and fuel pump seals) that contain
elastomer compounds incompatible with biodiesel, although the effect is lessened as
the biodiesel blend level is decreased. Experience during the last seven years with B20
has found that no changes to gaskets or hoses are necessary."

CBGraves · #6 02-28-2003, 12:01 PM

I've read about breakdown of rubber components with biodiesel, but what specifically, besides fuel lines, are likely to fail? How extensive is rubber used in the fuel system?

Michael, What do you estimate it is costing you per gallon when you brew your own?

McRoth · #7 02-28-2003, 12:17 PM

If you don't count my time, it costs me about $.30/gal.
I don't think there are any other rubber parts in the fuel system, but I don't know for sure.

CBGraves · #8 02-28-2003, 12:33 PM

Based on what I've read, the alcohol is far and away the most expensive ingredient. Are you recovering the un-reacted alcohol? What should I expect to pay for alcohol?

McRoth · #9 02-28-2003, 12:53 PM

I'm not recovering yet. I designed a recovery reactor, but haven't made it yet. I pay 1.22/gal for methanol, but I get it from where I work in 55 gallon drums, a paint factory. Some people get it from race tracks for $2-3/gallon. you might be able to find a chemical supplier to sell it to you for cheaper if you buy drums of it.