SEAL-D-RING 1156912 - Caterpillar

Scheduling a Top End Overhaul
Top end overhauls are scheduled according to the recession of the exhaust valve stems. This measurement provides an accurate indication of the rate of valve wear. This measurement can be used to predict when a cylinder head requires replacement.Measure the projection of the exhaust valve stems within the first 250 service hours. This measurement is the baseline. The baseline is a reference for subsequent measurements. Measure the projection again at the initial 1000 service hour mark. Use this measurement to determine when the next measurement should be taken.The maximum limit for the increase in the valve stem projection is 2.3 mm (0.09 inch). Plan for the top end overhaul as the valve stem projection approaches 70% of the maximum limit, or 1.6 mm (0.06 inch). Perform the top end overhaul before the valve stem projection has reached the 2.3 mm (0.09 inch) limit. Do not allow the projection of the exhaust valve stems to exceed this limit.Note: Generally, cylinder heads wear out at different rates. In some cases, servicing the cylinder heads at different times may be the most economic decision. This depends on the valve stem projection of the individual cylinders. However, this decision must include the costs of additional downtime that is caused by this procedure. Perform an economic analysis in order to determine if cylinder heads should be serviced as a group or divided into smaller groups.Note: The generator or the driven equipment may also require service when the engine overhaul is performed.Top End Overhaul Information
A top end overhaul involves servicing the cylinder heads and turbochargers. Also, some other engine components are inspected.Top end overhauls require more tools than preventive maintenance. The following tools are needed for restoring the engine to factory specifications:
Torque wrenches
Dial indicators
Accurate measurement tools
Cleaning equipment
Rebuilding equipmentCaterpillar dealers are equipped with these tools. Caterpillar dealers can provide a flat rate price for a top end overhaul.Unexpected problems may be found during a top end overhaul. Plan to correct these problems, if necessary.
Buildup in the cylinders from excessive oil consumption
Buildup in the cylinders from contamination of the fuel
Plugging of the aftercooler from coolant that is poorly maintained
Plugging of the aftercooler from contamination of the inlet air
Degradation of the oil cooler from hydrogen sulfide in the fuel
Leaks in the internal coolant passages in water cooled exhaust manifoldsInspect the following 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".Your Caterpillar dealer can provide these services and components. Your Caterpillar dealer can ensure that the components are operating within the appropriate specifications.If you elect to perform an overhaul without the services of a Caterpillar dealer, be aware of the following recommendations.Replacing of Components
Replace the following components during a top end overhaul.
Cylinder heads and gaskets
Oil temperature regulators
Water temperature regulatorsRebuilding of Components
Rebuild the following components during a top end overhaul:
Carburetor
Exhaust bypass
Gas regulator
Prelube pump
Starting motor
Turbochargers
Water pumpsNote: Periodic inspection of the turbocharger is recommended for