The engine is running smoother, quieter, and although veggie is supposed to have 6% less BTU, performance and mileage do not seem to be affected. Emissions definately have been affected positively. No black smoke and the exhaust smells better.


Steve Spence | Green Trust

VeggieBenz by Steve Spence

by Steve Spence, Dir., Green Trust

Project: Convert one beautiful classic car to run on used fryer oil!

Friday night, Christian Gundermann showed up with his 1980 MB 300TD wagon. A really premo ride with only 81k miles on it. We took it to Compeau's Quik Lube, in Massena, NY, where proprietor Frank Hillenbrand III, Christian, and I got busy.

How it works

We start the car on (bio)diesel, and hot coolant heats the veggie oil tank to 170F, then we switch over to veggie. When done driving, we switch back to (bio)diesel to clean the veggie out of the system.

Needed components

We purchased a Tankless Conversion Kit from Greasel as a start. This kit comes fairly complete, including a heat exchanger, hoses, wiring, valves, tank, filter, etc. We added a few hose clamps, hose pieces, and screws. We also added a 120vac 1000 watt coolant circulating tank heater for cold morning quick starts, and an optional, heated, spin-on racor veggie filter.

Step 1 - Install heat exchanger

First up was to install a heat exchanger in Christian's primary fuel tank. Christian wanted his factory tank to hold the heated oil, so we installed a 3 gallon tank in the spare tire well for diesel. We had to drain about 5 gallons of diesel from his tank before cutting into it with a grinder.


After the whole was cut out, Frank inserted the heat exchanger, and sealed with Permatex Rightstuff. A few screws to hold the plate, and this part is done.





Step 2 - Install lines

Next we ran Greasel's 3B hose from the rear of the car, up to the engine compartment, taking care to avoid suspension, driveline, and exhaust components. The 3B hose contains two coolant lines and a fuel line within an outer sleeve.


 We hooked up the 3B hose to the factory fuel tank, keeping the fuel return line in place, and hooked up the factory fuel line to the 3 gallon tank inside. Remember to open the tank "vent", as fuel starvation or tank collapse could occur.



Step 3 - Install hardware

Up front, we installed the Racor heated fuel filter, the circulating tank heater, the 3 port fuel selector solenoid, and the manual purge valve.




Flow diagrams

Initially, the fuel went from fuel tank to lift pump, then the filter, and finally the injector pump, with a return connector on the fuel filter sending fuel back to the tank. Remove the bolt (banjo nut) from the top of the factory fuel filter, and weld the bottom closed, to keep the system from pulling diesel from the filter during veggie operation, but still allowing the fuel loop (3 hoses, 3 holes in bolt) at the top of the bolt to work properly.

Now, fuel travels from the two tanks, through their respective filters, into the 3 port solenoid, then to the lift pump, and on to the injector pump. From the injector pump (by way of the banjo nut on top of the factory fuel filter), the fuel return goes to the manual purge valve. This is to remove air from the system. This has two positions:

  • Normal - passes fuel back to the input of the lift pump
  • Purge - passes fuel back to the veggie (factory) fuel tank.


Step 4 - Activating the system

A switch was mounted on the dash to activate the veggie/diesel selector valve, and the filter heater pad (68 watts) was wired into the hot on the glow plug circuit.



Step 5 - The heating system

The coolant lines were T'd at the rear right top of the engine (hot supply), and the front left bottom (cold return). We connected the coolant line to the veggie tank at the rear T, and the return coolant line to the Tank type recirculating heater, which then connected to the cold return T. The Tank type recirculating heater is directional, and needs to point towards the cold return.

We are done!

That's it, one nice smelling Benz. After 7 hours of work, I'm hungry. I wonder where those frys went ......

How it runs!

Update from Christian:

The engine is running smoother, quieter, and although veggie is supposed to have 6% less BTU, performance and mileage do not seem to be affected. Emissions definitely have been affected positively. No black smoke, and the exhaust smells better.

Order your own!

Give us a call, and you too can drive clean, and free.
Green-Trust / Beaver Creek Consulting
93 Sheldon Rd.
Winthrop, NY 13697
(315) 328-5726

The content & opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag

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