View Full Version : Tdi on veg oil

18th October 2006, 08:38 PM
The guy I was working with today has on old Merc that he runs on straight veg oil from a fish & chippery. The veg oil is in a 2nd tank and is heated and pumped to the engine. He uses about 8 litres per 100km.

He wants to sell the Merc and get a Tdi Disco, so we got talking Land Rovers & vege fuel. He worked in E.Timor and most buses & trucks there ran on straight coconut oil, but with our cold mornings, we need something to warm up the veg oil here.

He has more veg oil than he can use and as offered me a free fuel source.

Here are some questions I have :

Can a 300 Tdi fuel pump pull (suck) cold vege oil? There will be a heat exchanger between the pump and the fuel tank, but will the pump lift the fuel, or will I need to fit an aux. pump?

Does anyone here run veg oil in a Tdi?
With what results?
Should I use a fuel additive?
Should I bled it with diesel?
Does blending it with diesel make it easier to pump when cold?
What % do you blend?
He uses a 10 micron sock filter to filter the veg oil before use. He warms it up to accelerate the rate. I plan to warm filter it, then cold filter it on a 2nd run. However he doesn't find that it seperates or forms a skin in storage, even after one warm run through the 10 micron filter.

I will get some oil from him in the next few days and conduct a series of experiments.

I will :

Blend it 0%; 25%; 50% & 75% with diesel and see what happens when I store it for 2-3 weeks, put it in the fridge (simulate cold mornings) & expose it to daylight.

I'll be looking for seperation, discoloration, fungal growth etc.

Can anyone suggests any other tests?

Helton ( www.helton.com.au (http://www.helton.com.au)) do a heat exchanger for about $90. For those intersted they also do shower heat exchangers for $120. Great looking products at good prices, I only came across the website recently. I haven't bought anything yet.

As for a 2nd tank, I'm thinking of a jerrycan with a Tanami Pump style lid that incorporates the pick up and return lines. I mount the can into the bracket, clip on the lid with the pick ups and drive. When that runs out I pull the can out and put another in place. I suppose it can be mounted in the back of the Defender, as it's only cooking oil and not noxious fuel. The feed lines and return lines would be switched with a fuel solenoid from Brown Davies or similar. Anyway, that's just opening ideas, I'm open to suggestions and advise.


18th October 2006, 09:01 PM
Gutsy move Mike... I am even skittish about using the commercial bios' at the moment let alone a straight veggie oil..I see what the chippy pan looks like and don't want my cylinders/bores looking the same:mad: heat+oil =residue baked on crap that a steel pad can't remove...
Like i said gutsy move..on an old diesel maybe but not on my pride an joy..

18th October 2006, 09:10 PM
I haven't decided to use it yet. I'm researching at this stage. Maybe I should try a burn test as an experiment. Burn a spoon full of oil and a spoon ful of diesel and see what residue remains.

At this stage I'm still using BP only.

19th October 2006, 03:06 PM
There are thousands of people in europe running straight veg oil (SVO/WVO) on VW engines which use the SAME - BOSCH VE - injector pump as the TDI engine.

You do not need to worry about pumping cold veg oil - keep the changeover switch as close to the tank as possible, and always switch over to diesel a few km before you shut the engine off - to flush the lines with diesel.

Run injector cleaner regularly, as carbon trumpets can form on (direct) injectors when running SVO.

I plan to convert my landie soon, but it is a slightly different beast (3.9D).

19th October 2006, 09:44 PM


I found the above links informative. I only read them briefly at work though, I'll have a closer look at the whole site over the next few days. They seem to present pros and cons for the conversion and highlight potential risks (such a using copper lines). Apparently veg oil has 6 times the viscosity of diesel at 80 deg C and must reach 150 deg C to achieve the same viscosity, which would be a greater issue with multi-injection type injectors such as the TD5.

I'll keep reading....

19th October 2006, 10:00 PM
You need to be careful not to get vegie oil build-up in the engine sump. This can result from cold running and unburnt oil, and can lead to expen$ive repair bills.

19th October 2006, 10:06 PM
I have a Helton hot shower unit and am pleased with it. I wasn't aware they made heat exchangers for vegie oil.

Some places have stated that running on diesel until the engine warms up, produces a high enough temp in the injection pump to heat the vegie oil. But I don't see the harm in having a heat exchanger, especially in cooler climates.

19th October 2006, 10:18 PM
Another thing to consider, when using 2 tanks, is the fuel return from the injectors. When running on vegie, the fuel will be returning to the diesel tank.

This will reduce the mileage that you get from a tank of vegie oil, and will increase the vegie in the diesel tank.

One solution that some have used, is to return from the injectors, to the fuel line for the injection pump. But this may not be ideal when running on diesel (temperature of diesel fuel). You may be able to tee into the inlet of the fuel filter.

20th October 2006, 08:13 AM
Another thing to consider, when using 2 tanks, is the fuel return from the injectors. When running on vegie, the fuel will be returning to the diesel tank....

The guy with the Merc got a solenoid fuel tap from Brown Davies that switched return lines as well as fuel pick up lines. It was about $180.

From my reading of the aforementioned site, it seems that bio-diesel will be the safer option for the Tdi engine. That will mean having to consider overall costs, fuel excises, set-up inconvenience etc. But I'll continue to do the research, maybe if I can get 4-5 diesel owners and a big enough supply of oil, we can make it in big batches.