Mercedes biodiesel / diesel fuel system schematic

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Does anybody have any kind of schematic that will show me exactly how fuel system works on a Mercedes 300D?
My plans are to convert mine to run on biodiesel. I am torn between
using a inline, 12V electric fuel heater vs. a coolant heat exchanger in the aux. tank.
I would really like to retrofit this car to have a high output GM alternator anyway. Therefore, a 12V heater drawing about 15 or 20 amps shouldn't be a problem. This way, I could save a lot of coolant hose to the trunk, I could use biodiesel before the engine coolant/biodiesel is up to temperature, and I could regulate the temperature of the biodiesel easier with pulse width modulation control (cycle the 12V heater on and off every few seconds to achieve the desired biodiesel temperature).
This would probably require a small accumulator tank with an RTD or thermistor for fuel temperature feedback. The tank should prevent an unstable situation with the 12V heater. (i.e. the heater will not cycle on and off too quickly and ruin the relay that supplies power to the 12V heater).
If this works the way I would like it to, then I will surely use a PIC microcontroller and programming to:
-automatically run the tank selector valves -take feedback from the biodiesel temperature -turn the 12V heater on or off based on that temperature feedback -automatically switch back to regular diesel when biodiesel tank gets too low -automatically switch back to regular diesel when the key is turned off and allow the engine to run for a few seconds. This will allow the biodiesel to purge out of the fuel system. This way the engine can't be shut off on biodiesel. (My engine is turned off with an electronically actuated, pneumatic valve due to my previous remote start / keyless entry installation)
I want to have a switch with 3 positions; Biodiesel, diesel, and auto. Where "auto" will automatically select bio or diesel based on system feedback. Maybe a couple LED's... to show which take is active.
Has anyone used only an electric heater to heat the Bio fuel? If so, it would be nice if you could share a couple pictures and a description.
Thanks,
Craig DFW Texas 1984 Mercedes 300D Turbodiesel - 280K today.
In case you can't tell, I am one of those crazy EE's :)
Penn State all the way...
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http://www.greaseworks.org/index.php
These guys have done a lot of Biodiesel figuring out.
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[300D]

[...]
Craig, no disrespect intended, but...I just can't wrap my brain around the idea of why so many people want to go to the trouble and expense of buying a relatively inexpensive, economical and reliable older car and spend so much time and effort on a Rube Goldbergian alternative-fuel set-up (with a dosey-doe and an elleman-left, in your case) when the car runs just fine as-is -- and plenty economically, to boot, even considering today's high fuel prices. To each his own and all that, but...sheesh! Why not just drive the thing in stock form and be con- tent with what you have? Which, I can tell you (having owned a W123 300D) is plenty?
Aside: Why is it that anytime fuel prices spike, diesel fuel goes from being cheaper than regular gas to being more expensive than premium -- and does so literally overnight? Why does that happen at all, and why does it happen so quickly? It used to be that even when gas prices went up, diesel got more expensive too but was still cheaper than gasoline. Nobody has ever explained this to my satisfaction. yes, China and India are using more fuel than they used to -- but they use gasoline as well as diesel, probably much more.
Geoff
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Well, I would like a much cheaper fuel option. Most of all, I want to do it for my hobby. I love to tinker on vehicles and build circuits. I had a senior project in college that was similar to this (in respect to creating a control system using a programmable microcontroller). Control systems, after all, is what I have a passion for and I got my B.S.E.E. with an emphasis on control.
The concept is very simple and so is the car. Personally I don't think it is difficult or really expensive to do. I do think it will take some time to create this system. I just want to build a "good" system and share it with those having the same interest. I also like the fact that I can integrate a microcontroller into this and write code to optimize control of this system.
So really, it goes further than just wanting cheaper fuel for me.
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snipped-for-privacy@gmail.com wrote:

Forgive my likely ignorance on this important subject but isn't there a significant difference between Biodiesel and just plain vegetable oil? Biodiesel has the glycerol taken out by transesterification and so has a similar viscosity to fossil diesel and when the weather gets cold in the UK at least they mix more fossil diesel and other additives with the biodiesel to decrease viscosity. So do you really need a heater with commercially produced biodiesel, especially living in a hot climate like Texas?
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Nihil wrote:
[snip]

Well, having lived in Texas long enough to know that it does get cold there in Dallas and North Texas during the winter. Sometimes cold enough to have occasional ice storm or light snow (or even rare blizzard). Winter as we know does exist in Texas Panhandle every year.
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One reason I have seen is that previously diesel was a minor byproduct in the refining process and so could be sold at lower, 'marginal' prices. With diesel demand having risen refineries have to be run to make diesel, which raises the price.
This is for the underlying price before taxes, of course. In a number of European countries diesel is taxed at a lower rate than petrol for socio-political reasons. In Britain this difference has been eliminated and so our diesel is dearer than petrol. The difference was never as great as in some other European countries anyway.
DAS
For direct contact replace nospam with schmetterling
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On Fri, 25 Aug 2006 18:25:18 +0100, "Dori A Schmetterling"

that's all possible but in the US the current wholesale price of #2 diesel is about .16 to .20 cents UNDER the price of 87 octane no lead gas. someone is screwing the consumer
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I'm so shocked. That almost never happens with the oil companies.
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On Fri, 25 Aug 2006 20:09:19 +0000 (UTC), snipped-for-privacy@news.vrx.net (Richard Sexton) wrote:

actually at this point in time I am very wrong, I just checked prices and in NY Harbor no lead gas is about $1.90 a gallon and #2 diesel is about $2.04 a gallon so the OP is correct in his observation that diesel is now over regular gas. The pricing I referred to was constant for the last 60 days or so, but I haven't been paying close attention to the market.
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Here in the Silicon Valley area it's now over *premium* gas, and has been for several weeks. The same thing happened when fuel prices went up last year.
Diesel in the Bay Area is now running at about $3.39 a gallon. That's the price at the cheapest gas station in my area, as a matter of fact (the Rotten Robbie station on Lafayette St. in Santa Clara, for the benefit of any locals in the readership).
Geoff
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On 26 Aug 2006 10:37:32 -0700, snipped-for-privacy@u1.netgate.net (Geoff Miller) wrote:

California is it's own unique market that has little relationship to the rest of the US
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That's true for gasoline, but diesel fuel is diesel fuel. There's no special California formulation for California.
Geoff
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On 27 Aug 2006 09:40:35 -0700, snipped-for-privacy@u1.netgate.net (Geoff Miller) wrote:

true, but diesel like gas is a product of distillation, and CA's refineries operate differently than anyone else's and the ratio of #2 to gasoline is skewed because of the different refining procedures.
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What's "#2 diesel"?
DAS
For direct contact replace nospam with schmetterling
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On Sat, 26 Aug 2006 00:08:20 +0100, "Dori A Schmetterling"
it's what we use , you guys call it gasoil
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We don't. (The French might.)
What is #1 diesel, then?
DAS
For direct contact replace nospam with schmetterling
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On Sat, 26 Aug 2006 11:03:31 +0100, "Dori A Schmetterling"

a similar blend, less cetane
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Used for what? (In what circumstances?)
I have not noticed two grades of diesel at our pumps.
DAS
For direct contact replace nospam with schmetterling
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On Sat, 26 Aug 2006 11:46:04 +0100, "Dori A Schmetterling"

you rarely see #1, I've only seen it sold in the western US, maybe the more scientific inclined can explain
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