Preventive Maintenance — Can it be Simplified?

Items in your maintenance schedule fall into one of three categories...preventive maintenance items, revolution-sensitive items and load-sensitive items.

Preventive maintenance items should be performed at the hours indicated on the schedule. If not, engine life and performance will be adversely affected.

The maintenance intervals for revolution-sensitive items are based on hours of operation. The faster and longer the engine runs, the faster the components wear. The load on the engine during operation does not affect these items.

Obviously, load-sensitive items are affected by engine load. The best indicator for determining service intervals for load-sensitive items is total fuel consumed, which will vary as the load on the engine varies. In general, the lower the load, the longer the engine life. If revolution-sensitive components are serviced at the proper interval, the risk of a failure is minimized for most users.

If you decide to exceed the indicated intervals in the schedules, you assume a higher risk of component failure and unnecessary expense.

As mentioned, the wear rate of load-sensitive items is a function of fuel consumed. An engine operating at 100 percent load takes less time to consume the same amount of fuel as an engine operating at 50 percent load. It follows that it takes less time for an engine operating at 100 percent load to wear the same amount as an engine operating at 50 percent load.

Of course, engine load will fluctuate, making it difficult to determine the exact hour interval for servicing. It’s therefore important to keep accurate fuel consumption records to properly maintain load-sensitive items.

Here’s a list of items that require regular preventive maintenance:

Revolution-Sensitive Items

  • Water pumps
  • Alternators
  • Fuel transfer pumps
  • Oil pumps 

Load-Sensitive Items

  • Cylinder liners
  • Cylinder heads
  • Connecting rods
  • Pistons
  • Piston rings
  • Main and connecting rod bearings
  • Valve train components


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