keeping them running
Page 43
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by TrevorLongcroft
Engine fitters are all too aware of the damage caused to fuelinjection equipment by allowing contaminated fuel to pass through it. Water, one of the contaminants, can quickly render a precision-built pump useless.
Most diesel-fuel systems, of course, incorporate a water separator — normally between the tank and lift pump — which effectively separates out any water or coarse solid impurities from the fuel before they reach the filters. However, the efficient operation of these units depends upon regular draining of accumulated water from the transparent bowl beneath the separating element. Failure to empty the bowl will eventually make the unit inoperative and already contaminated fuel maybe further contaminated as it is passed through the separator to the fuel pump.
I have recently come across a unit, the Harwood Indicating Water Separator Mk 5, which has a float /valve assembly in the bowl, and this prevents contaminated fuel reaching the fuel pump even when the bowl is full. When the water reaches a predetermined level, a magnet fitted to the float energizes a remote light which, in the case of a truck, could be mounted on the cab dash.
An alternative to light indication is an automatic dump device which will spill any excess water accumulated beyond the predetermined level. Should the visual warning be ignored or the alternative system not operate and the water level continue to rise, the float-mounted cut-off valve restricts the flow of fuel to the fuel pump, shutting down the engine before contaminated fuel can reach it.
The separator is manufactured by C. T. London (Harwood) Ltd, Holland House, Burmester Road, London, SW17.