Well, this diesel veggie oil page may not sit well with everyone, because it is full of potentially discouraging news. At Karmakanix we have a tendency to call a spade a spade. This is one of those times. Veggie oil conversion takes some basic forms. We are not going to use the popular acronyms, as they can be confusing, and there are middle grounds where these acronyms don’t work. Karmakanix is NOT here to discourage people. We are here to provide excellent customer service. We are on your side. Read this, but don’t weep. Just decide if you are willing to deal with all the consequences in your mission to save the world. Don’t make the obvious mistakes along the way. We are here to help!
Single Tank Diesel Veggie Oil Systems
Veggie oil cannot normally be used to start a diesel engine with a stock fuel system. It must be heated up first to flow well enough to be injected. There are some systems, such as the Elsbett German System, that are known as single tank, because they can start a cold engine, but only so cold. Alaska: Forget it. These Elsbett systems use special large hole injectors, a heating blanket for the fuel filter, heating tapes for the injector lines, and a series of relays and temperature sensors to change the temperature signals to the engine computer and glow plug systems. Elsbett also includes a bulky veggie to coolant heater/filter tank to warm up the juice. Works OK for bay area usage. Like all veggie systems, a separate pump is used to feed the diesel injection pump, as the diesel injection pump cannot suck the fuel from the tank. That does change the internal primary fuel pressure in the pump, but not enough to damage anything. It just kind of confuses the electronic controls, but they get by. Some systems cleverly reroute the return line directly to the fuel pump inlet. The idea is to keep the fuel hot. Not such a good idea, since the internal primary pressure inside the fuel pump skyrockets, and the electronic controls go nuts. The Elsbett design is well done, they have even designed and manufactured an engine specifically for veggie oil usage. And it is a world’s first.
Dual Tank Diesel Veggie Oil Systems
Most diesel veggie oil customers elect to use a dual tank system. A diesel or biodiesel tank is used to start and heat up the motor. A second veggie tank supplies veggie oil once the engine is hot and the veggie oil is preheated. There are many ways that Karmakanix has seen through which the veggie oil is heated. Some worse than others. The only acceptable way to heat the veggie without overheating it is a with coolant/veggie interface. Here are some of the other systems we have seen and why they did not work out well. 1) Electric barbeque charcoal starter as a heater in the fuel tank. Caused massive deposits of baked on veggie oil in the tank and throughout the system. 2) Veggie hoses wrapped around the exhaust pipe. Go figure. 4) The diesel tank part of the system was a plastic fuel tank bungee corded to a frame rail inside the engine compartment. A hole was melting in the side of it from engine heat. Go figure again. 5) High current in line heater just before the pump, often combined with coolant heating. The Veggie oil overheats, and invariably inevitably forms massive amounts of scum and gunk deposits inside entire fuel system over a relatively short amount of time.
Other problems we have encountered: A) In all systems, seepage is pretty much inevitable. Veggie oil forms the same scum on engines as it does on your olive oil bottle at home, only much faster and firmer since engine heat is involved. B) The scum cannot be cleaned with anything that won’t melt engine components. C) The scum gets on fasteners and must be chiseled off before a wrench or socket can be used. D) The scum capillaries up inside all the threads, so all fasteners must be forced to turn for their entire lengths. E) Many systems use hoses of incompatible sizes and cheesy hose clamps that really contribute to the seepage problem.
Every system is different and represents that individual’s brainchild. The myriad of hoses, valves, solenoids and pumps must be assessed before diagnosis or any work can proceed. Brainchilds can be very confusing, even to the inventor. And especially to the mechanic who has to sort it out to fix it. Karmakanix can do that. We have had many challenges over the years. Be prepared for some extra hours of labor.
Every system must purge the diesel from the system as it fills with veggie oil after warming up. Every system must purge the veggie oil from the system before shutting down. A system left full of veggie oil will not restart once it is cold. The only successful way to start a cold system full of veggie oil is to tow the car in gear for some distance until it starts. Not pretty, and that won’t work with automatic transmissions. Every time this purge cycle goes on, some veggie is leaked into the diesel/biodiesel tank, and vice versa. Contrary to popular belief, Veggie oil will not mix with diesel or biodiesel. Just because they are cousins, does not mean they can mix. That veggie oil forms scum, especially because it has been hot. The scum will eventually contaminate the inside of the fuel system until something fails. You fix that and later another thing fails. Et Cetera, until the pump gets gooey or an injector fails. At some indeterminate point, the system will have to be replaced.
Alameda County had two veggie Volkswagens with the latest and greatest diesel veggie oil systems. Handmade aluminum tanks, nice coolant lines to the trunk, restriction monitoring gauges, computer control changeover valves, etc. Most systems have issues at 4-5 years old. Their problems started at two years because every official wanted to drive the world-saving car, and everyone pulled the changeover trigger many times per day. At two years, they started bringing the cars to Karmakanix to sort out the failures. At 3 1/2 years they bought their own tow truck to get them home when the systems clogged. The only real solution was complete systems replacement on both cars. They abandoned ship. Design and use your system wisely.
Diesel Veggie engines have another inherent problem: Carbon production. The pity is that there is a standoff. The hotter the veggie oil gets, the more efficient the burn, and the less carbon produced. But the faster it builds scum. Overheated oil disintegrates. Veggie oil at 200 degrees F makes less scum, but does not burn as well and forms more carbon. The carbon is not like carbon in your regular diesel or gasser engine. This carbon is gooey. It makes the VNT turbochargers stick. Eventually, it forms large amounts of carbon at the intake valves until the engine is breathing through a hole the size of a dime. The engine must be disassembled to clean out the problem. It will happen, and Karmakanix just considers this the cost of the technology. Some customers do not see it that way. Take precautions and assume driving habits to extend the life of your system and engine. Run your engine at consistently higher rpms. Stay above 1200 rpm while driving in the lower gears. Keep the rpms above 1500 – 1600 for the top two gears. This will help minimize the carbon issue.
Waste Veggie Oil vs. Brand New Oil
Karmakanix has found that the engines running new veggie oil have far less problems for many more years than those running waste veggie oil, or recycled cooking oil. We believe this is because the new veggie oil is purer and hardier as a molecule. Waste oil has a myriad of contaminants including water, no matter how finely one filters it. Some contaminants are just smaller than the finest filters. We consider a damaged oil molecule to be just another form of contaminant, as it does not burn well. It contributes to excessive and gooey carbon buildup. To be basically blunt about veggie oil: If you would not eat it, do not feed it to your motor.
At Karmakanix, we hear about the early Mercedes cars running diesel veggie oil for year and years. Volkswagen Tdi is different. The Mercedes is an old school engine, runs rather cold, with medium compression. The turbo has no modern electronic boost pressure controls. The engine has a hardy fuel pump with 5 separate pistons instead of a fuel distributor. That fuel pump has no complicated electronic controls. The injectors have post holes compared to the 192 micrometer holes of a Tdi injector. Success is a relative thing.
The Final Advice: Save the World, One Molecule at a Time
Karmakanix is not here to change the world or the people, We have a decades of experience with diesel veggie oil cars. We fix cars. We understand and agree with those customers who want to change and save the world. We do not have all the answers, such as how to clean scum. But we are here to advise you on how to keep a veggie system alive, should that be your course of action. Basically: Think about Elsbett as an alternative. Complicated, but likely to last longer. Use fresh oil, brand new. Expensive, but longer lived systems. Think about Greasecar Systems, and plan on using their most recent and expensive system, as it is more precise and reduces scum. Karmakanix can explain helpful further modifications. Plan on some expensive maintenance and repairs. If you choose to use waste oil, plan on the consequences. Don’t do this to save money. The system, the maintenance and the repairs will cost much of what you save. Do it to save the world.