Engine
SHOP MANUAL
Ch 1 page 23
Fuel initially contains a reduced quantity of water rom the manufacturing process. The water content may in-
crease, e.g. as a result of condensation, during prolonged and unsuitable storage.
Small quantities of water in the fuel do not affect the engine operation. However, micro-organisms grow in the
water. The microbes obtain nourishment from the oil and their growth is therefore greatest in the
boundary layer between the water and oil. In an emulsion the boundary layer is very large and emulsification
therefore encourages growth.
The cause of breakdowns can generally be attributed to badly maintained
supply tanks. Water, dirt, fungi and/or bacteria have collected in tanks which
are rarely cleaned or drained. They form a mass which can block filters.
There are additives which counteract this, but we would warn against their
use since they are hazardous
environmental toxins which affect the microflora.
In our experience the established oil companies maintain their tanks in such a way that contamination of this
kind does not occur. Where problems have occurred, the tank has not been maintained correctly.
The oil companies do not use toxic substances, but rely entirely on regular cleaning and drainage of water from
the tanks. The latter should, however, be carried out only some days after the tank has been filled, so that the
water has sunk to the bottom.
Drainage is carried out at all stages of the distribution, both in depots and at filling stations. Heat is applied to
larger, cooled tanks to reduce the fuel iscosity, resulting in internal circulation to accelerate the precipitation
before draining the water.
De-contamination
Tanks:
- Clean large supply tanks carefully inside and dry them before filling them with new fuel.
- Drain the water a few days after filling and at regular intervals from then on in accordance with the oil
supplier’s instructions.
Engines installed in vehicles, boats etc.:
- Clean the entire fuel system, otherwise the microbial flora will spread again.
- Rinse the fuel lines and blow them dry.
Replace fuel filters.
- Clean the fuel tank.
- If the contamination was very serious, it may be necessary to inspect the injectors and injection pump and
remove any deposits that may have formed. Experience has shown that biological tissue can penetrate the fuel
filter
and may create deposits in those parts of the system beyond the filter.
- Biocides may be used as a last resort. The individual tank owner should refrain from handling such substanc-
es. Any such use should take place with the assistance of the fuel supplier.
Summer and winter fuels
(Available on markets with cold climates)
Fuel can be adjusted to the seasons by adding lighter components and removing components which can
crystallise out at low temperatures. It is mainly the higher paraffinic hydrocarbons which crystallise out and
these help to increase the ignition value.
The winter fuel has a lower density and lower viscosity. This results in a reduction in engine output.
Environmental fuel
Environmental fuel with markedly reduced sulphur contents and therefore emissions is available on various
markets. Normally the density and viscosity is also lower for these fuels.
By using output correction curves (formulae), the outputs can be corrected for the effect of density and viscosity.
See the table on page 7 for the specification of diesel fuel complying with Swedish environmental classification.
Important information about the fuel
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