Why do people suggest i run biodiesel in an older diesel engine?

Question

I understand the alterations that have to be made with vegetable oil fuels, but what is it about older engines that they 'run better on biodiesel'? is it heating, design, lower restrictions?

Answer 1

Because the vegetable oil fuels are more viscous, or thicker, than conventional diesel which provides additional sealing around compression rings and valves which tend to lose their sealing ability in older engines.

Answer 2

Older engines are more forgiving.  The new ones have all the additional technology, tend to break down more and are engineered to require more refining.

Answer 3

Cylescho  has most of it.  

The engine was original designed to use vegetable oil.  Germany has no oil of it's own so they needed an engine that would run on what they had.  

Petroleum is cheaper than soybean oil.  Well not at $140.00 a barrel.

Answer 4

Much of it is down to the Enigine Management Sytem. Since 2005, car manufacturers have been under much tighter emmissions restrictions, so the systems have become more complex over time. The key factors for bio-desel are that they now measure the rate of compression in the engine, and also the oxygen content into and out of the exhaust.

Bio-diesel has a lower energy content than mineral, but "ignites" more easily under compression- in other words, it makes the engine think that there is a problem with the pressure on the fuel, so the engine may try to compensate.

Bio-diesel also has a higher oxygen content than mineral- the exhaust monitors read this as not enough fuel getting to the engine, so increase the flow-rate of the fuel to the pistons. Since bio-diesel has better lubricity than mineral, this means that too great an amount of fuel reaches the pistons, it then compresses at too low a level, so it reads a problem with the fuel, disagreeing with the exhaust monitors..... etc etc.

Most often, this is easily compensated by running a mix of bio-diesel/mineral diesel (usually around B85), although some vehicles are more sensitive than others.

Older vehicles, which do not have these tight restrictions on the Management System, tend to run a lot more easily on B100- hence the advice you've been given.

Hope this information helps.