Hi,

I been reading on this forum for a few days because I am planning to convert my 1994 250TD to a OM605 Turbo with electonic pump and 722.6. I learned a lot and since I have some experience with WVO I want to share my experiences.

Here in Germany, we have quite a big community of WVO users. I guess for one reason we have very high fuel costs for a very long time now. So I have been using WVO for the last 12 years now. I started with a 1985 200D, a few years later with a 1989 300D, my 1994 250TD and my 1991 200D Automatic.

I used many different sorts of WVO, the best fuel which I still use today, is a vegetable sunflower oil (not fat), that was used for frying, and is filtered through a centrifuge. This oil is useable at every temperature, even in the winter at -20° Celcius (with minimal difficulties)

In the beginning, i made quite a lot of modifications to the engine, which over the years proved senseless. First thing I installed with a lot of effort, was a two-tank fuel system which turned out to be totally senseless for the prechamber engines with inline injection pumps (Not for the 220D with lucas pump). Later I installed a big fuel/water heat exchanger to heat the thick WVO up and make it liquid. Turned out, the injection pump is the best preheating device. I also installed electical pumps at the fuel tank to force the fuel to the engine. I learned that the lift pump is strong enough for vegetable oils as long as they are liquid (everything you can put in the fuel tank through a funnel). For greases you need these pumps.

So, for waste wegetable oils, I do these modifications to the w124s:

- cut out the fuel filter in the fuel tank

- install a large fuel line from the tank to the engine compartment. For a 200D, 10mm inner diameter will be enough, for all other engines i use 12mm. I use normal polyamide pipes, as they are used for compressed air in trucks (2€/m). Using smaller diameters causes "undersugaring" of the engine at low temperatures when the engine is cold. The fuel tank will heat up when the engine heats it over the flowing back fuel, but when the fues tank is full, it can take up to 100km. I use a fuel pressure gauge to measure the fuel pressure at the intake of the inline pump, optimum is +0,6 bar. After a cold start on a winter morning with -10°C under full load, the pressure should at least stay over 0,1 bar. The engine begins stuttering at -0,5 bar (yes, the inline injection pump can suck quite good, but not when there is air in the line).

- In the engine compartment, I send the fuel from the big line from the tank into a 8mm ID rubber hose, as it is used originally. It is flowing through a normal inline prefilter through the original fuel-water heat exchanger (the thermostat is thrown out) into the lift pump. From there as it is built by the engineers originally. Since 4-Valve engines have the thermostat inside the heat-exchanger housing and it tends to get leaky with vegetable oil, I normally dont use this preheater. The original prefilter can be used and is practical to clean on the road, but I also get better results using a standard inline-prefilter. On the 4V-engines, all the O-Rings on the fuel lines should be replaced, viton is not necessary (maybe after 10 years of biodiesel).

- I set the injection timing 3 degrees earlier, to the 12° after OT mark (on non-turbo-engines). Injection nozzles are replaced and set to 135 bar (worked best for me). To compensate the higher pressure, a half turn on the fuel quantity screw is needed (never really understood why that happens since its a hydraulic system, I guess the the high-pressure fuel lines are expanding under higher pressure)

- a catalysator helps to minimize the exhaust smell

With these modifications I got my cars running for the last 12 years and 360.000km. I always use 100% WVO, No Diesel or Petrol fuel in the tank, even in the winter. Under 0°c I need to preglow for 30 seconds to get the engine started without using the starter for more than 3 seconds. The 4V-engines start a log better than the 2V. Even at hot summer temperatures, at a cold start the engine is always running shaky blowing blue smoke out of the exhaust.

I never had problems with fuel in the engine oil, at least it has never smelled like vegetable oil. Oil level stays constant from oil change to oil change (10000km), maybe the burnt oil is filled up with fuel. Also I had never problems with burning residuals in the cylinders. As leaking cylinder head gaskets are a normal problem on the OM60x (except the turbo ones with the metal gasket) i have seen all my engines from inside, also the prechambers which I pulled, never had any more residuals than engines driven on diesel. Power is also no issue, only the top speed is only reached after some driving. While my 300D reaches top speed of 200km/h on Diesel immediately, on WVO is sticks at 190, after 15 minutes of fast driving it is no problem to reach 200km/h for the rest of the day. Last year I drove 800km from munich to hamburg, the engine reached GPS 207 in the flat land after one hour of almost constant over-200-driving.

On my second 200D I tried waste motor oil one winter long. I work in a Mercedes-Benz truck workshop, I put the 40l of old engine oil from the Actros directly into my fuel tank. Engine modifications as described above. At first I had no problems. Engine started like it was diesel, just smelled a bit. But three mornings later the good times were gone. From that day on, I had to use the starter for at least 20 seconds to get the engine running. I never solved this problem, I guess the engine lost compression. I did the head gasket some time later, everything looked normal. I put some Petrol on the pistons, but it did not run very fast into the oil pan. Maybe the injection pump is damaged, too. Prechambers were filled completely with coal, i cleaned them, but the problem stayed. Injectors were replaced, glow plugs of course. Liftpump is OK, too. The problem stayed. Even when I use WVO. I dont drive the car any more, just used it in the winters cause it is in quite bad shape. Otherwise I would have tried changing the pump.

I hope my experiences are of some interest.

Thanks, I'm keeping notes just in case petro goes up again but currently here in Virginia we a paying $2.52 a gallon, about .60 Euros a liter for Diesel. I was running BioD, VVO, WVO in my trucks and my car and I enjoyed a great savings even with the occasional gelling but it's not cost effective any more.

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1993 MB 300D 245K died.

Great post! Thanks for sharing your experiences!

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Baton Rouge, LA
1977 300D Non-Turbo

Thanks for your post. It corroborates the consensus one finds reading German wvo sites: a much simplified approach i.e. minimal modifications - and more mere reliance on the stock set up of the car to be able to deal with the vegetable oil. Counter-intuitive considering the German penchant for over-engineering.

Although, as you state, "even at hot summer temperatures, at a cold start the engine is always running shaky blowing blue smoke out of the exhaust" would suggest that the incomplete combustion taking place under those conditions could lead to unwanted deposits (coking),leading to problems in the long term.

Perhaps this is offset by the (very) high speeds and predominantly autobahn driving that you guys do over there compared to type of driving done here in the US, which allow your cars to run cleaner and not end up being affected by coking which gets burned away?

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'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.

I find it really, really strange that you encountered problems so soon after using WMO, and not from WVO. That runs counter to everything i've heard from people who have run both, although this was in large engined diesel pickup trucks. I have also seen an awful lot of ruined W123 diesels from tree hugging hippies trying to run WVO through them.

I personally have run a WMO mixture in my 5.9 litre Cummins Turbodiesel truck for tens of thousands of miles without so much as a hiccup. Note this is a mixture of WMO and diesel fuel, not just straight WMO. I have also run a mixture of the same fuel in my 1978 OM617 non-turbo MB diesel with no ill effects.

Like WDBCB20 mentioned already, I do have to wonder of the freeway speeds have a lot to do with your successes.

I still cannot figure out how three days of driving on WMO permanently downgraded/disabled your car's performance. A piston soak with a carbon dissolving solvent (Kreen - for example) may help restore the spring tension to the rings if there is coking deposits built up in the ring lands.

I am curious as to what you will eventually discover is the culprit?

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2007 Dodge Ram 3500 Cummins Turbo Diesel 4x4
1994 GMC S-15 pickup 4.3 5MT
1985 300 SD
1978 300 CD
1962 220-S Fintail - awaiting restoration

Hi, thanks for your answers.

Its not as if we go top speed every day over here. For me and my wife, driving on the highway is happening only when were going on holiday or some other event far away. Normally, we drive city and overland with top speeds of 120 kmh. My wife is quite a slow driver, she prefers to stay behind the trucks at 90kmh and never uses full throttle. Under these conditions, none of our cars had issues with carbon or anything like it in the engine. The cars are also equipped with Diesel catalysts in the exhaust, I would think those getting blocked would be an issue with bad burning fuel. Never had any problems with that. Bzt when you drive the cars really slow and dont rev over 2500 for a long time, the exhaust seems to get full of soot. When you rev it over 4500 then, you end up with a black wall behind you.
I experimented with much higher injection pressure (160 bar) and very early injection (up to 7 degrees earlier). The result was a better engine start without shaking in the summer, but a lot louder engine with less power and heat problems in the prechambers under full load.

The waste motor oil experiment might have been more successful with engine oil from a petrol car. The truck oil has a lot of soot in it and is used for 100.000km from change to change. But I think a prechamber engine might not be the optimal choice for this fuel. Direct injection will prevent any dirt from thr burning process staying in the engine.
I guess I will never know what the problem with myengine was. The car still exists, but I will drive it to Africa this autumn for holiday and leave it there.

If you go with wvo,do not use the stock fuel tank if its metal.I went back to diesel 3 years ago,even had my tank dropped and cleaned.I still have problems to this day,with this chicken slime blocking my fuel filter.I have to clean filter every 300 miles.I use gasoline to back flush primary filter.I do have wmo saved for emergency fuel,when war breaks out.I use only gas vehicle oils,I cut with 50% diesel.I figure used diesel oil,has so much carbon,it would sand injection pump,and injectors over time.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran