Biodiesel / vegetable oil questions for a mercedes diesel?

Question

i have a mercedes diesel 350sdl 1991.

I am considering using alternative fuel. Ok from my understanding biodiesel and vegetable oil are different. To run off vegetable oil, you need to install special equipment in your car, but with biodiesel you can just pour it into the tank? (as long as the biodiesel is treated to have no junk it).

The stuff you get from restaurants - that would be veggy oil - and you can use a machine to convert it to biodiesel that can be put directly into the fuel tank?

Answer 1

Yes, the difference is that biodiesel is a chemical modification of vegetable oil, to make it thinner.   Vegetable oil by itself is too thick (viscous) at room temperature to go through your car's fuel system.  There are two ways to deal with that:

1. Modify the fuel (everytime) by brewing biodiesel.

2. Modify the car (once) to preheat the veggie oil to about 120-150 degrees so it's thin enough to go through the fuel system.   Usually you have 2 tanks, one for diesel/biodiesel to run the car on until it warms up, then you flip a valve and run virgin straight veggie oil (SVO) or waste vegetable oil (WVO).  You switch it back to diesel in the last few minutes (one song on the radio) of running, so the SVO/WVO is purged from the system and it's ready to coldstart again.

Using WVO is a little tricky, here are three types of contamination you need to think about:

Big #1.  Particulate.  Tiny bits of french fries in the fuel.  You MUST pre-filter your waste oil before you put it in the car's fuel tank, and you must pre-filter it FINER than the car's fuel filter (or else the particles will just clog the filter).

#2. Water.  Water in fuel oil is bad and will clog up filters and corrode tank, pump and injectors.

#3 Acidity.  Used oil tends to be acidic from the foods and this can corrode your tank, fuel pump and injectors.

If you use a 2-tank system, you might get away with not solving problems #2 and #3, because the contaminated fuel would only be in the injection system while you were running, and purged before shutdown.

You could solve problem #3 with titration and washing (similar to what's done in making biodiesel) and #2 with water separation (similar to what's done in makin biodiesel).  Gee, seems like almost as much work as making biodiesel :-b

Virgin SVO is much less likely to have these problems. Last I looked, a 5-gallon (35 pound) fryer pack of "vegetable oil" was $2.59/gal. at CostCo.

Answer 2

its easy to make if you have the time, a good supply of waste veggie oil and like making stuff in the shed.

Answer 3

Yes.  There plenty of folks driving Mercedes, VWs, construction vehicles etc.  using biodiesel.  It is still controversial though.  However, Texas law currently does not prohibit you making your own.  The machine you need can be created for under $500.  We can literally live on the fat of the land.

Answer 4

Biodiesel can be sold at the pump and put straight in the 3.5L engine.

You can make your own "appleseed" processor, but then you have to do that each and every time you need fuel.  

What's better is to add a 2nd tank that perfectly fits in the spare tire recess in the trunk.  Since the SDL is Mercedes big boat, you won't even notice the weight of the extra fuel.

Flip a switch after a minute, and you're running on vegetable oil.

I'm not going to be partial so look at these kits and decide for yourself.  

http://greasecar.com/kit_selected.cfm?se...

http://www.frybrid.com/kittest.htm

http://www.plantdrive.com/shop/home.php?...

Good Luck

Answer 5

The difference is that with biodiesel someone else has cleaned it but vegetable oil still has components that are better used to make plastics (a Soybean Producers plant in Volga, near Brookings, S.D. is already using soy oil to produce a plastics precursor) otherwise your injectors

can foul and pistons freeze. Used veggie oil from fastfood places can be made into biodiesel with filtering and heat/pressure treating it. Probably not worth the effort and expense. I've seen several web sites showing how to do this (ask Mother Earth News) but it is pretty energy intensive itself. Plus remember the Second Law of Thermodynamics, processes involving changes of state always (in this universe) lose energy.   michael