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Details about converting a Mercedes Benz 300TD to run on used vegetable oil.

Mercedes Benz Waste Vegetable Oil Conversion Project



This DIY waste vegetable oil conversion is based around three simple points which are outlined below.
  1. At 160° Fahrenheit used vegetable oil will act the same in the injection system as diesel fuel.
  2. The Vegetable oil must be filtered at least as well as the stock fuel system filters diesel and the filters should be large and easy to replace.
  3. The motor must be shut down and started up on diesel (or biodiesel).
After working with the grease system and talking to other people who had converted it became apparent that looping the fuel return was the only way reliably heat the grease to 160°. If the fuel return is not looped back to the input of the injection pump you will never maintain the required 160° minimum temperature inside the fuel system.

For details on specific stages of the conversion check out the Conversion section on the left, or the links at the top of the page.

Before: After:

Tank heater

The way I designed the tank heater is probably only feasible on the 300d sedan due to the orientation of the fuel tank. If you want to design your own, go for it.. pretty much anything you can do to heat the fuel pickup area is going to be beneficial. Use a cheap range hose like I did, or have a custom pickup made.. the important parts are:

1. Make sure there is no possible way the coolant can leak into the tank
2. Make a good seal, so the grease doesn't leak out of the tank
3. Maximize the amount of hot surface area exposed to the cold grease
4. Maximize coolant flow through the system

There are so many variables involved when trying to measure how fast the tank heats up, such as how full it is, ambient temperature, type of driving I'm doing, etc, so I've never gotten a really good measurement on it. I will say though that after driving around town for a few hours, the whole tank is rather warm to the touch and the whole trunk is emitting heat. So I think I did a pretty good job, especially since it cost around $15 (for the hose and a tube of JB weld). :-)

re: Wasteful

Heh,

It's been running for two years and over 20,000 miles. So if you have a better way and more information, why don't you share it?

-Jay

A better way is to use

A better way is to use regular Diesel, what these engines were designed to run. It says "Diesel" on the trunk and fuel flap for a good reason.

re: Oil Analysis Reports

After every oil change I've been sending it to Blackstone Labs to have it analysed. They have been finding high levels of potassium, sodium, and lead in the oil. We both thought that the veggie oil was contaminating the motor oil and causing excessive wear on the engine. So as an experiment I drove the car about 2,000 miles on straight diesel fuel and had the oil tested again. The potassium and sodium were still present, thus it is probably a coolant leak somewhere.

I put all of the oil reports online, the comments tell a bit more of the story.

-Jay

True True

I need to update the site.. those pictures are from the old tank. But yes, you are totally correct. Even though I only put WVO in the tank, it still ate away the JB weld and caused a leak.

I ended up totally re-doing the hose in hose system and tank heater.

There are pics here: http://greasebenz.com/newpics/index.html

One day I'll get around to integrating them onto the website ;-)

Cheers,

-Jay

**EDIT** The new tank heater design is now part of the main site.

You have been a very busy

You have been a very busy man. JAY. Good job on the hose in hose. HIH. What is that electric water heater temp controler doing under your hood? That gave me a great idea. LOL Is that to control the amount of heat you have or do you have it set up to switch over your valve once the grease gets to 180+. SMART MAN.

P.S. Cute kitty.

Thanks Michael

So if you don't mind me asking how much did your complete home made grease kit end up costing you?

Austin Bio-Diesel Coop/ Diesel Green Fuels LLC
98 Jetta TDI / grease car kit + veggie therm.
michaelmullins (at) dieselgreenfuels.com