The shift in performance of injectors fitted to diesel engines has been well documented in our previous presentations and with field trials carried out on mines in South Africa and Botswana.
In one of these trials flow increases, on new injectors, of 6.7% within 105 Hrs of operation were shown in stall tests on a Caterpillar dump truck.
Although most of the wasted fuel was blown out of the exhaust system as sooty carbon particles a certain percentage was carried down into the crankcase oil past the piston rings.
The lighter ends of this unburnt fuel will vaporise off quite quickly but the heavy ends will mix in with the oil where heat, churning and mixing with oxygen within the engine oil sump will cause this fuel to oxidise forming acidic gums and sludge. Although this process does not take place immediately as additives like rust and oxidation inhibitors, anti-foam and detergent/dispersants in the oil will slow this degradation down these acidic and sticky compounds are not good for an engine.
In the manufacturing process of engine oils, chemicals called viscosity index improvers are added to oil so that it will not thin down as much with increases in temperature. As a result, the oil can operate in a much wider temperature range and give improved protection to the engine at higher and more efficient operating temperatures. Contamination with the heavy ends of diesel fuel that are not vaporised off will lower the viscosity of the engine oil but will not be detected as fuel dilution with the standard flash test. This mixture with a lower viscosity has a much reduced ability to lubricate the engine properly and can result in shortened equipment life, high maintenance costs and increased downtime.
Ultra-fine filtration of the fuel before it gets to the pump and injectors will allow these precision components to work the way they were designed to and ensure complete combustion of the fuel within the combustion chamber. This means that much less unburnt fuel is thrown out of the exhaust and carried down into the crankcase oil. This improved burn will translate into better fuel consumption and/or engine performance depending on the operating style of the driver of the vehicle. Where loads are constant as in gen sets, pumps etc. the fuel saving will be more evident than on mobile, driver operated machines.
Tests carried out on a fleet of busses graphically illustrate what happens when dirty fuel affects the performance of diesel injectors.
The above sample shows that the crankcase oil is closer to the new oil specification after a UDF fuel filtration system was fitted to this bus. After reconditioned injectors were fitted the viscosity dropped and this may be as a result of injector spay-hole wear on old replacement injectors or it could also be caused by leakage past existing pitting on the seat area. The fitting of reconditioned injectors is not recommended as a best practice.
The OEM fuel filter fitted to these engines has a manufacturer’s rating of 10 µ no beta ratio was quoted) and is a standard pleated paper, area filter.
After the fitment of the UDF systems to five busses the average change in viscosity of the engine oil on these vehicles was from 89.6 to 93 centistokes. This shows that ultra-fine fuel filtration improves the combustion process within the cylinders improving the over-all average fuel consumption.
UDF fuel filtration systems remove 95% of all contamination above 0.5 µ
from a diesel engines fuel system, protecting expensive pumps, injectors and
turbo chargers whilst saving on fuel costs, repairs and downtime.
UDF fuel filtration systems are part of a pro-active maintenance programme