Probably the biggest problem and drawback associated with converting your car to run on vegetable oil is the cold start problem, something I discovered only too well within a couple of months of converting. Put simply, because I forgot to flip a little switch one afternoon, the following morning I couldn't start my car. I'll explain more about this below, but first a few pertinent questions:
There's a lot of question above and they're there for a reason. All of them are answered in what follows and may be of use to someone else browsing this site for information.
So, let's look at the problem...
As I said above, simply because I forgot to switch from Vegetable Oil to Ordinary Diesel two minutes before the end of my day's journey, the following day I couldn't start my car because the engine was full of vegetable oil.
Because vegetable oil is viscous, it has trouble squeezing through all those necessary parts that make your diesel engine run, and most particularly through the injectors. Hot vegetable oil has little trouble because it's nice and liquefied, but the colder the vegetable oil, the thicker and more viscous it becomes, and the harder it gets to start an engine.
Not all cars are the same. Older vehicles with more basic diesel engines tend to be fine with pure vegetable oil, even on cold days, though they may have to crank a while to start. However, modern diesel engines, such as that found in my car, just can't cope.
When I came to start my car it was a cool summers morning, around 7.30am with a temperature of just 14°C. I sat down, turned the key and listened to the sound of an engine that just wasn't going to start. I must have sat there five minutes trying and trying again, but there was no way that cold vegetable oil was going to start my engine - and the engine and fuel pipes were full of it.
If I haven't made this clear elsewhere, this is how a two-stage vegetable oil conversion system works.
As you can see from the above, ordinary diesel is still very much a part of the two-stage process, but it's use is significantly reduced. From my personal experience, I've found I use somewhere like 75 to 85% less ordinary diesel, which is kinder to my pocket and the planet.
It should be clear from this why a two-stage system is critical to the modern diesel engine. Without that initial run on ordinary diesel, most modern engines simply wouldn't start. Furthermore they are prone to wear and damage.
By failing to switch off the system, I failed to provide my engine with enough diesel in the engine and fuel pipes to get it started. If it had been a hot summers day, maybe I would have stood a chance, but that was not to be. Consequently I needed to find out how to start on engine full of cold vegetable oil.
Credit where it's due, I telephoned the guys at DieselVeg (DieselVeg no longer trade - click here for other fitters) who fitted my system and told them the story. It's one they've heard many times before. I guess everyone running this system makes this mistake sooner or later.
Thankfully the solution didn't involve anything too mechanical otherwise my meager talents may have caused me problems.
The answer to the problem lay in a two strange places, the kitchen and my wife's dressing table.
After guiding words from DieselVeg, I removed the large protective cover from my engine, located the common rail (or to the technically minded like myself - the metal bit with lots of metal pipes coming from it on the side of the engine block). From there I set about heating this up with a combination of hot water (being careful to avoid electrics) and my wife's hairdryer.
Sure enough, after several minutes the metal became hot and, presumably, the oil within it became more viscous.
After some more noisy cranking of the engine, it finally caught and started. I didn't hang around and took it out for a quick run to get things moving again.
So will I make the same mistake again? I'm bound to. But at least I know the solution now.
However, the solution is timely and awkward, so clearly it's better not to have to use this if it can be avoided. So please, learn from my mistakes - not yours.
“Remember that the happiest people are not those who are getting more, but those giving more” - H Jackson Brown JR.
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