The project: Convert the mercedes benz 300D sedan to run on WVO (waste vegetable oil) fuel.
Current info:
08/26/06: Just returned from a 5580 mile trip fueled completely on vegetable oil.
07/17/06: The oil was changed and a sample sent to Blackstone Laboratories for analysis. Read the report here
06/16/06: The pulley is fixed and holding. The heater core now has two valves and allow it to be taken out of the coolant loop. Also, a vacuum gauge was installed in between the primary and secondary filters.
The secondary filter ( $20 fuel filter) becomes clogged much faster than the primary filter ( $5 oil filter). After reading this study I've come to the conslusion that oil filters are not worth a damn and have been exploring other methods of filtration such as prefiltering, cleanable oil filter elements, and Frantz style toilet paper roll filter.
05/23/06: DISASTER STRIKES! The pegs holding the crankshaft pulley have sheared off AGAIN!
05/12/06: Just returned from a 1200 mile round trip journey to New Orleans. The veggie filters were changed prior to the trip, and they clogged again about 500 miles into the trip. They were changed and are still in use some 600 miles later. Its possible that a rather dirty load of grease was introduced, thereby shortening the lifespan of the filters. One cool thing about veg is that I was able to run the tank completely empty from completely full and get a pretty accurate mileage calculation. 21.1 gallons / 496 miles = 23.5 MPG.
As this was the first real test of the car, several improvements are on the way.
- 1. The method of having the heater core in series with the veggie heating system causes the inside of the car to get too hot. It will have to be valved off and on somehow.
- 2. It is nearly impossible to tell which filter is clogged except by trial and error. A vacuum gauge will be installed in the fuel system to measure the condition of the fuel system.
- 3. An auxiliary fuel pump should be installed to pump veg through the first filter. I think the lift pump is having trouble sucking oil through the primary filter which causes it to "clog" before it should. This should also improve priming times after the filters are changed.
04/29/06: Website mostly updated. Car is running strong and is now my daily driver. The engine is very sensitive to air in the fuel system. Good thing the excellent engineers at Mercedes Benz thought to install a fuel primer on the lift pump!
04/23/06: The conversion is complete. The return loop, dump valve, LEDs, and assorted switches were installed today in a coffee induced frenzy. Pics coming soon.
04/20/06: The Mercedes is currently taken apart and waiting for secondary fuel filtration (20 micron + 5 micron) installation. The fuel return lines have also started to leak slightly. I replaced one of the segments with 1/8" clear fuel line (I will have to double check that measurement) purchased at the hardware store. Its designed for lawn mowers, and seems to be holding up very well.
03/25/06: The Mercedes was filled up with B99 Biodiesel from Eco-Wise. (Why B99? The Federal Government provides significant financial incentive to the sale of blended biodiesel, and B99 is as near to B100 as can be sold while still qualifying for the incentive.) Biodiesel has a tendency to degrade natural rubber in fuel lines and most people recommend changing the fuel lines on cars made before the mid 1990's.
My motto: if it ain't broke, don't fix it. I also have spares in the trunk.Mileage calculation #1: 351 miles on 17.7 gallons = 19.8 MPG
20 MPG is a bit disappointing, but I do have a lead foot.
Useful Links:- Austin Biodiesel coopmessage board
- Frybrid Lots of good info. Check out their resources section and forums. The theory section is a good place to start for anyone wanting to find out more about WVO conversions.
- The MercedesShop.com Forum. Excellent resource for anything Mercedes related.
- Diesel Giant The Mercedes diesel maintenance tips section has pictorials on everything from changing the fuel lines to adjusting the valves.
- Blackstone Laboratories Engine Oil Analysis.
- Russ W. Knize's oil filter study
Before After 
