804129T Mercury EXHAUST VALVE

A top end overhaul involves the removal, the inspection, and the rework of the cylinder head components. Some additional components are replaced and serviced.Your Cat dealer can provide these services and components. Your Cat dealer can ensure that the components are operating within the appropriate specifications.Note: The driven equipment may also require service when the engine is overhauled. Refer to the literature that is provided by the OEM of the driven equipment.First Top End Overhaul
If you elect to perform an overhaul without the services of a Cat dealer, be aware of the following recommendations.Cylinder Head Assembly
Inspect the cylinder head assembly according to the instructions that are in Cat reusability publications. Refer to Guidelines for Reusable Parts and Salvage Operations, SEBF8029, "Index of Publications on Reusability or Salvage of Used Parts".Your Cat dealer can provide these services and components. Your Cat dealer can ensure that the components are operating within the appropriate specifications.The use of out-of-spec parts will cause unscheduled downtime and/or costly repairs.Unit Injectors
Replace the unit injectors. Consult your Cat dealer about exchanging the unit injectors. Your Cat dealer can provide these services and components.The wear of unit injectors is affected by the following considerations:
Quality of the fuel
Quality of the filtration of the fuelThe wear of the unit injectors can result in elevated levels of exhaust emissions and/or poor engine performance. The misfire of a single cylinder is not typically attributed to normal wear. This condition can be repaired by replacing the faulty unit injector.The following lists of circumstances indicate that the unit injectors should be inspected more frequently:
Use of fuels that are not recommended in this Operation and Maintenance Manual, "Refill Capacities and Recommendations"
Extreme ambient temperatures that reduce the ability of the fuel to provide lubrication
Frequent plugging of the fuel filters
Insufficient maintenance of the fuel tank or the fuel storage tank that can allow excessive water, sediment, and other foreign matter.
Insufficient maintenance of the fuel filtersOil Suction Screen
Clean the oil suction screen after the oil has been drained.Note: Approximately 1 L (1 qt) of oil will remain in the oil housing after the sump has been drained. This oil will pour out of the oil housing when the cover is removed. Prepare to catch the oil in a pan. Clean up any spilled oil with absorbent towels or pillows. DO NOT use absorbent particles to clean up the oil.
Remove the cover.
Remove the screen assembly according to the instructions in the Service Manual, "Disassembly and Assembly" module. Discard the used O-ring seals.
Inspect the screen assembly. Obtain a new screen assembly, if necessary.
Wash the screen assembly in clean nonflammable solvent. Allow the screen assembly to dry before installation.
Install the screen assembly and install new O-ring seals according to the instructions in the Service Manual, "Disassembly and Assembly" module.
Install the cover.
Remove side covers in order to gain access to the sump. Clean the bottom of the