1982 Mercedes-Benz 300TDEnlarge Photo
cooling system TeeEnlarge Photo
1. Cooling System Tee
The primary source of heat to turn thick, cold vegetable oil into thin, hot fuel is antifreeze from the radiator. Using a plastic three-way Tee from NAPA auto parts, one simply taps into this line coming from the heater core and going to the cylinder head.
16-plate heat exchangerEnlarge Photo
2. 16-plate Heat Exchanger
The lower right line you see in the picture above is the one that came from the cooling system Tee. It flows hot radiator fluid through this 16-plate bronzed copper heat exchanger. Notice the smaller lines on the left side, both lower and upper? Those carry cold vegetable oil from the tank, which flows from bottom to top through a labyrinth of tiny tubes (like a radiator) that are heated by antifreeze from the radiator. This is the first point of heat for the cold vegetable oil.
4 micron filter + heat exchangerEnlarge Photo
3. Heat Exchanger / Vegetable Oil Filter
Engine coolant (radiator antifreeze) must flow through another heat exchanger before its trip back to the radiator. The heat exchanger above is combined with a filter. The entire device above both filters the vegetable oil to remove impurities and particles, as well as heating it another time to bring it up to high temperatures. Notice the smaller lines at the bottom of the device? These flow once-heated vegetable oil out of the 16-plate heat exchanger, send it through a heat exchanger warmed by engine coolant for a second heating, send it through the orange Baldwin 4-micron oil filter, and then back out and onto the mechanical fuel pump. The coolant has now done its oil heating duties and is ready for return to the car's cooling system.
cooling system TeeEnlarge Photo
4. Return Cooling System Tee
Having been re-routed through two heat exchangers, the hot coolant flows across the engine bay to another NAPA 3-way Tee and re-enters the car's engine cooling system.
toggle switchEnlarge Photo
5. Dash Toggle Switch
When starting on a cold morning, the car's radiator is, naturally, also cold. How to warm the system up while the vegetable oil is too cold to burn? Flip this toggle switch that powers two fuel selector valves that route diesel fuel from a small tank to get things going.
6. Fuel Selector Valve
The fuel selector valve, above, and another one just below it, always flow out the left port, but alternate between the right upper and lower ports for flow into the valve depending upon whether the dash toggle switch is on or off. The upper valves connect to the vegetable oil system going to the car's main fuel tank where vegetable oil is stored. The lower valves go to the purge tank, a small one-gallon tank located in the left fender well filled with diesel #2 for startup and shutdown purposes only.
purge tankEnlarge Photo
7. Purge Tank
When the dash toggle switch is turned to the on position, fuel is both drawn from and returned to this one-gallon purge tank located in the left fender well. This allows the engine to start, heat up, and gradually send hot antifreeze through the heat exchangers, warming up the thick vegetable oil the point where it can be used as fuel for the engine. The purge tank is also employed a few minutes before shutting off the engine at the close of the day in order to clear all fuel lines and the fuel pump of any remaining vegetable oil that could thicken in the lines and injectors overnight.