Mining Machinery & Vehicles

Diesel engine’s injector failures

26th August 2015 • By

Injector failures is something that is not always monitored. We have a failure, decide whether it is a warranty case or not and book it to the breakdown cost subjected to the machine. However, there is a hidden cost compiling from each machine’s injection system that is not measured. Every machine has a specific load it can carry and it has to carry that load at a specific time interval over a distance. If the machine has a loss of engine performance, it effects the production capability of the machine and therefore a loss in production over time. We therefore have to cases, a ‘catastrophic’ failure of the injection system and the functional failure of the injection system.

With the ‘functional’ failure the injection system can no longer operate at its designed specifications. This causes a loss of engine performance, higher fuel consumption and an irregular spray pattern which can ultimately lead to breakdown.

One particular way to be informed on a predictive basis is to use your oil analysis program and ‘flag’ certain parameters like your SOOT and TAN levels to pick up on contaminated fuel.

SOOT: The first method of being informed on a preventative basis is within the sampling of the engine oil. If after the analysis a high level of SOOT is found, it indicates a high number of carbon within the engine oil. This causes more wear to take place and shorten the life of the on-board filtration.

Total Acid Number [TAN]: The second method lies with the Total Acid Number [TAN]. This represents levels of sulphur and therefore suggest an improper combustion process that cause these contaminants to “blow by” the piston rings and find its way in to the engine oil. This is caused by high sulphur fuel and promotes oil oxidation by depleting the additives. The question remains then: What is causing this wear on my injection system? Well, the greatest enhancers of wear is Silica and water.

SILICA

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Silica represents dirt ingression, whether it is from the bulk fuel storage or on board the machine itself and can cause serious damage at the high pressure the common rail operates by.  These contaminants cause further wear within the system and can cause ‘silting’ to take place within the moving parts.  It also causes erosive wear due to the velocity and pressure the fuel is injected by. These are two of the main reasons for injector failures.

WATER

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High PPMW or percentage saturation levels within fuel can cause corrosion to take place within the system and cause catastrophic failure to the common rail, the injectors and the high pressure fuel pump.

Contaminants cause wear, which cause irregular spray patterns that lead to performance loss and ultimately, injection failure. By implementing efficient filtration on board and on the fuel storage facilities, these hidden costs can be controlled and even prevented to enhance the operation of the fleet and save costs that were previously allocated to breakdowns.

Thank you for taking the time to read this paper. I look forward to your thoughts on this.