HOSE AS 8Q5772 - Caterpillar

ModelsSome examples have been found of fuel injection pumps and nozzles which were damaged by contaminants (dirt and other foreign material) in the fuel. The source of these contaminants was fuel which was used to fill new filter elements before installation on the engine. When this is done, the unfiltered (dirty) fuel gets into the clean side of the filter element, and flows directly into the pumps and nozzles. These parts are easily damaged by the contaminants in the unfiltered fuel, and the cost of replacement is high.
For this reason, the recommendation is that fuel filter elements not be filled with fuel before installation. When new filter elements are installed, use the correct procedure to prime the fuel system as shown in the Lubrication and Maintenance Guide. Use of correct procedures to install filters and prime the fuel system will make sure that only clean fuel flows into the fuel injection pumps and nozzles. This will extend the service life of these components, and keep replacement costs at a minimum.