Mercedes Diesel Fuel System Upgrade Question For Use With Biodiesel

You can simplify all that confusing stuff as follows: The car was NOT designed to run on Biodiesel, used frying grease, peanut oil, or any other of the "fad" fuels. The fun of using all that c__p is being able to tell your "green" friends that you are saving the earth.

You will pay the penalty in mileage, performance, maintenance and longevity.

Bill Ditmire Ditmire Motorworks,Inc.

Actually, well made biodiesel will burn the same as diesel. The key is "well made" as the quality varies a lot. Also, some of the things used by some manufactures can break down some of the rubber. (Now you can see why quality varies) The first question to ask is, "Why do you want to use it?" If the answer is only economic, skip biodiesel. If it is because you have a source of free grease, and can get the other chemicals cheap, and can make it yourself for under $.50 a gallon, than your own skill is the major question. If it is to "save the planet" just rebuild your big car or SUV as an electric hybrid with a small diesel generator, and run plane diesel, or biodiesel, after picking the right generator.

Lee

I've owned a '80 300SD since new and know something about the model. It's engine is highly developed (for its time); its parts are designed to work with each other, not some altered concept, so be conservative about making any changes.

The worst thing some owners do to their cars is "mess with" a perfectly running car. So don't. This engine is "old technology" respect it and maintain it. Keep its valves adjusted and, if it smokes, install remanufactured Bosch injection nozzles to improve fuel atomization and so reduce smoke etc.

If rubber component erosion is a real issue as opposed to a rumor (and lots of those get posted here) then I'd forget about converting a '79 car to anything. Be happy it runs well and is reliable. A failed "conversion" essentially scraps the car for the repair cost may exceed the car's (running) value prior to the failure. A new injection pump or perhaps even a professionally remanufactured injection pump probably costs more than you paid for the car so be prudent in what you do.

In Europe about 40% of new cars are diesel powered, there's even a new diesel Jaguar! These new diesels use sophisticated electronically controlled fuel injection systems and depend on high quality diesel fuel to achieve their high power and very low emissions. Biodiesel home brew is too variable to be considered a high quality fuel, IMHO.

My car is actually pretty well maintained. Doesn't smoke or anything like that. I agree with you that any drastic changes, including changing to a different type of fuel (while designed to be interoperable), can turn a perfectly good car into junk.

On the flipside though, the National Biodiesel Board has a standard for biodiesel in terms of its quality and chemical properties which ensures that it won't kill a working engine. So the worst thing that might happen is that it just won't work well. According to the NBB itself, the natural rubber fuel components may be a problem when using 100% biodiesel (they call it B100), while a 20% biodiesel / 80% petro-diesel mix does not cause these problems.

Another thing about the old diesel engines according to the NBB is that since they use IDI (InDirect Injection) with a prechamber, they can actually handle problematic fuels better (if biodiesel would prove to be problematic at all) than the new DI (Direct Injection) diesels.

So either way, I'm wondering which parts of the fuel system are made of (natural and/or butyl) rubber and need to be replaced, as well as where I could get the synthetic replacement. Any ideas?

Daniel

I doubt anyone here will know the answer to your question.

Thanks Lee, I'll try that. Good to know that the injection pump has rubber seals, too :)

Daniel