POTENTIOMETER 4W5971 - Caterpillar

Scheduling an In-Frame Overhaul
Generally, an in-frame overhaul is performed for every third top end overhaul. Scheduling an in-frame overhaul normally depends on the following three conditions:
An increase of oil consumption
An increase of crankcase blowby
A decrease and a variation of cylinder compressionEach individual condition may not indicate a need for an overhaul. However, evaluating the three conditions together is the most accurate method of determining when an overhaul is necessary.The engine does not require an overhaul if the engine is operating within acceptable limits for oil consumption, crankcase blowby, and cylinder compression.Periodically measure each of the three conditions. The first measurement should occur during the engine commissioning. This establishes a baseline for future measurements. Additional measurements are scheduled at regular intervals in order to determine a schedule for the next in-frame overhaul.The following changes in the three conditions normally require a scheduled overhaul:
A 300 percent increase in oil consumption
A 200 percent increase in crankcase blowby
A 20 percent loss of cylinder compressionNote: These indications do not require an engine to be shut down for service. These indications only mean that an engine should be scheduled for service in the near future. If the engine operation is satisfactory, an immediate overhaul is not a requirement.Monitor the engine as the engine accumulates service hours. Consult your Caterpillar dealer about scheduling a major overhaul.Usually, an in-frame overhaul does not require removal of the engine. Instead, the service is performed with the engine in place. If the customer requires a minimum disruption in the production of power, the engine can be replaced with a rebuilt model of identical specifications.Note: The generator or the driven equipment may also require service when the engine overhaul is performed. Refer to the literature that is provided by the OEM of the driven equipment.In-Frame Overhaul Information
An in-frame overhaul includes all of the work that is done for a top end overhaul. Additionally, some other components that wear are replaced. The condition of components is inspected. Those components are replaced, if necessary.Your Caterpillar dealer can provide these services and components. Your Caterpillar dealer can ensure that the components are operating within the appropriate specifications.The following definitions explain the terminology for the services that are performed during an overhaul:Inspect - Inspect the components according to the instructions that are in Caterpillar reusability publications. Refer to Guidelines for Reusable Parts and Salvage Operations, SEBF8029, "Index of Publications on Reusability or Salvage of Used Parts". The guidelines were developed in order to help Caterpillar dealers and customers to avoid unnecessary expenditures. New parts are not required if the existing parts can still be used, reconditioned, or repaired. If the components are not in the reusability guidelines, refer to the Service Manual, "Specifications" module.Rebuild - The component can be reconditioned in order to comply with reusability guidelines.Replace - The service life of the part is exhausted. The part may fail before the next maintenance interval. The part must be replaced with a part that meets functional specifications. The replacement part may be a new