Preventative Maintenance (Routeone magazine issue 176 - 19.04.07)
One of the greatest contributors to operating cost is the roadside breakdown - stranded passengers, drivers hours ticking away and reliance on the manufacturer`s lifeline breakdown service.
Rear engined vehicles suffer with overheating problems unless the cooling system is inspected regularly. The water and charge air radiators which are double banked to save space become fouled on the airside usually in the space between the two - the powerful fans acting as vacuum cleaners drawing in leaves and plastic bags. Gradually the fouling margin will be exceeded then at full power the engine will overheat. It is extremely difficult to clear out this debris with the radiators in situ. Sealing the gap round the outside of the radiators not only improves air flow across the cooling surface but also reduces the ingress of larger items of debris between them. Compressed air or high pressure water should be used regularly to keep the radiator core clear. The inside of the radiator will remain fairly clear of contamination due to the corrosion inhibitors in coolants.
Adequate engine cooling relies on the pressure within the system being maintained. Leakage or a failed pressure cap will reduce performance particularly at altitude or where prolonged high engine power is required.
A turbocharger centre bearing failure can lead to a high ingress of dirty engine oil entering the intercooler radiator and fouling the tube walls reducing intercooler efficiency. When replacing a turbocharger it is good policy to flush out the intercooler. Loss of power will occur if the intercooler leaks or becomes inefficient leading to the engine management system lowering the power output to compensate for the reduction of charge air to the cylinders.
Analysis of failures away from base shows that windscreen wipers are high on the list. Keeping the wiper arm securing nuts tight saves much trouble. These loosen gradually on the tapers which causes wear by slipping necessitating spindle replacement.
Lubrication of all locks and hinges particularly on wheel arch panels saves time and effort when fitting snow chains on winter ski work. These items require regular attention and exercising to prevent seizure particularly in the winter months when road salt accelerates corrosion.
Common breakdowns occur due to fuel starvation - the prime cause being blocked filters. Strict monitoring and regular changing of all filters will prevent many problems as will checking fuel line unions for possible air ingress points.
Compressed air filters and dryers should be checked for function. Lubricant ingress upstream of the air dryer from a worn compressor will shorten the life of the desiccant. Air line lubricators which keep air cylinders and door actuators working freely should be topped up with the correct grade of oil.
The main cause of air conditioning plant failure is dirty airside evaporator filters causing high pressure drop. In the summer it will be necessary to change these twice a month.
Electrical problems are mainly related to poor charging. Alternators should be checked for output. It is possible for an alternator to fail without there being any visible warning. This places a higher load on the other which will then burn out. Battery casings should be washed off at each inspection and terminals checked for cleanliness and security. Chassis/body to engine earth cables should be checked for continuity and security - inadequate earthing causes poor starting and increases the risk of fire.
Top of the list for failures is belt shedding. There can be as many as a dozen drive belts connecting the crankshaft to the water pump, aircon compressor, alternators and cooling fan. Failure of one of these belts can “de-rail” several more. The vehicle should carry a complete set of spare belts some of which are not readily available at the roadside. Driver education on keeping engine revs in the green sector and regular inspection of the belts and the tensioner bearings minimises the risk of failure.
Operators having Scania Comfort Shift gearboxes should make sure that the fault code RAM (random access memory) is downloaded and analysed regularly to highlight any driver related use and abuse of the transmission. Failure to do this will result in gear change difficulties when the memory becomes full. Drivers should be trained on how to operate this type of gearbox in safe mode allowing movement of the vehicle to a place of safety should a problem occur.
The days have gone when the driver could be expected to solve a problem other than a minor one, although some old timers still carry a substantial tool kit. My own experience over many years of continental touring proved that simple checks by fitting staff and drivers before leaving the depot, in addition to the mandatory walk-round safety check, will prevent many breakdowns which are beyond the driver`s ability to correct at the roadside.
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