While
it is true that any diesel vehicle can be run on biodiesel with no modifications,
this statement should be further qualified to account for the inescapable hand
of Father Time. In the short-term, any diesel vehicle can be run off of
neat biodiesel (B100 or 100% biodiesel) with no modifications. In the
long-term, however, B100 use will eventually degrade non-compatible rubber fuel lines and
gaskets within the fuel delivery system of your vehicle.
The one exception to this rule is newer diesel vehicles that
come equipped from the factory with biodiesel compatible fuel hoses, though we are seeing many more issues with newer diesel models than originally thought. Conventional wisdom holds that starting somewhere in the mid-90's all diesel vehicles started being produced with compatible hoses. We know that the VW TDIs have one set of hoses (injector return lines) that will eventually degrade with biodiesel use. We have also seen many TDIs coming into the shop with injection pump seals that are leaking and need to be replaced/updated. Please contact us if this happens to your car as you do not need a new IP, and we can save you at least $1000 in unnecessary repair bills.
Ford PowerStroke models circa 1994-1998 also have non-compatible hoses that may need to be replaced.
For older vehicles running straight biodiesel that do not have
B100 compatible fuel hoses, the biodiesel user will soon begin to notice
degradation taking place in the form of hose "sweating", or permeation.
This is visually observable as a shiny, lustrous, sheen on the surface of the
fuel hose, and can be confirmed via the Greasy Hand Test: Grab the hose
with an ungloved hand, release, and examine hand to determine whether or not
it is coated in a greasy film.
Biodiesel permeation of fuel lines is the first sign of fuel
hose degradation, and does not appear to affect performance. However,
if "sweaty" hoses are left on the vehicle, the next phase of degradation--loss
of elasticity--can hinder performance. When a fuel hose loses its elasticity
it becomes mushy, and does not exhibit rebound when exposed to the Squeeze Test:
Squeeze the suspect hose between two fingers and note its elasticity or rebound.
If it does not spring back to round, it has failed this test and should be replaced.
Hoses that cannot hold their round shape are prone to collapsing under the relatively
low-pressure vacuum (3-8 in/Hg on pre-92 VW diesels) of the fuel injection pump,
thus restricting fuel-flow and potentially leading to a fuel-starved engine.
The next phase of fuel hose degradation is hose swelling and
splitting. This is generally a long-term phenomena (>6 months B100
use) and will eventually lead to a complete failure of the affected hose, either
by a breach in the hose wall, or by literally melting an end off, usually at
a hose clamp.
While many hoses seem to initially handle B100 quite nicely,
very few can handle continued B100 use over the long-term. Viton® fluoroelastomer hose is one group of hoses that is B100 resistant over the long-term, (rated at 400* F continuous
use), and is far and away the best option at present for long-term B100 use.
All of the vehicles we restore have been retrofitted with B100 compatible fuel
hoses to ensure long-term biodiesel compatibility. Also, we provide Viton® hoses in most common sizes for B100 upgrades, as well as providing pre-made kits to fit your particular vehicle.
Click here
for a study on B100 fuel hose compatibility.
Check out our online store for custom fitted Viton® hose kits for a variety of vehicles.
