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.
If you elect to perform an overhaul without the services of a Caterpillar dealer, be aware of the following recommendations.
Inspect the cylinder head assembly 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 Cat dealer can provide these services and components. Your Caterpillar 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.
Replace the unit injectors. Consult your Cat dealer about exchanging the unit injectors. Your Caterpillar 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 fuel
The 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 filters
Clean the oil suction screen after the oil has been drained.
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| Illustration 1 | g02251853 |
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Top view of a typical 3500 engine oil pan with an oil housing and oil suction screen. (1) Cover (2) Oil suction screen | |
- Remove the cover (1).
- Remove the screen assembly (2) according to the instructions in the Service Manual, "Disassembly and Assembly" module. Discard the used O-ring seals.
- Inspect the screen assembly (2). Obtain a new screen assembly, if necessary.
- Wash the screen assembly (2) in clean nonflammable solvent. Allow the screen assembly (2) to dry before installation.
- Install the screen assembly (2) and install new O-ring seals according to the instructions in the Service Manual, "Disassembly and Assembly" module.
- Install the cover (1).
- Remove side covers to gain access to the sump. Clean the bottom of the sump with absorbent towels or pillows. When the bottom of the sump is clean, install the side covers.
Note: Approximately
Clean, Inspect, and Pressure Test Components
- Aftercooler core
Replace the following components during the top end overhaul:
- Electronic unit injectors
- Turbocharger cartridge
- Pressure sensors
- Temperature sensors
Inspection, Reconditioning, or Exchanging of Components
Inspect 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".
Recondition the worn components or exchange the components, if necessary. Your Caterpillar dealer can provide these services and components.
- Camshaft followers
- Cylinder head assembly
- Engine wiring harness
- Exhaust manifold seals
- Exhaust manifold bellows
- Fuel pressure regulating valve
- Fuel priming pump
- Fuel transfer pump
- Inlet manifold gaskets
- Inlet manifold seals
- Oil pump
- Prelube pump
- Pressure sensors
- Pushrods
- Rocker arms
- Spacer plate
- Software update
- Temperature sensors
- Turbocharger
Inspect 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".
- Camshaft
- Driven equipment (alignment)
- Engine control module
- Oil suction screen
If you elect to perform an overhaul without the services of a Cat dealer, be aware of the following recommendations.
Inspect the cylinder head assembly 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 Cat dealer can provide these services and components. Your Caterpillar 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.
Replace the unit injectors. Consult your Cat dealer about exchanging the unit injectors. Your Caterpillar 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 fuel
The 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 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 contaminants.
- Insufficient maintenance of the fuel filters
Clean the oil suction screen after the oil has been drained.
- Remove the screen assembly according to the instructions in the Service Manual, "Disassembly and Assembly" module. Discard the used O-ring seals.
- Wash the screen assembly in clean nonflammable solvent. Allow the screen assembly to dry before installation.
- Remove side covers to gain access to the sump. Clean the bottom of the sump with absorbent towels or pillows. When the bottom of the sump is clean, install the side covers.
- Inspect the screen assembly for good condition. Obtain a new screen assembly, if necessary. Install the screen assembly. Install new O-ring seals.
Note: Approximately
Replace the following components during the second top end overhaul:
- Electronic unit injectors
- Catalyst Module
- Pressure sensors
- Temperature sensors
Inspection, Reconditioning, or Exchanging of Components
Inspect 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".
Recondition the worn components or exchange the components, if necessary. Your Caterpillar dealer can provide these services and components.
- Auxiliary water pump
- Camshaft followers
- Connecting rods
- Critical fasteners
- Cylinder head assembly
- Engine mounts
- Engine wiring harness
- Exhaust manifold seals
- Exhaust manifold bellows
- Fuel pressure regulating valve
- Fuel priming pump
- Fuel transfer pump
- Inlet manifold gaskets
- Inlet manifold seals
- Oil pump
- Pistons
- Piston pins
- Prelube pump
- Pressure sensors
- Pushrods
- Rocker arms
- Spacer plate
- Starter
- Software update
- Temperature sensors
- Turbocharger
- Water pump
Inspect 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".
- Camshaft
- Crankshaft
- Driven equipment (alignment)
- Engine control module
- Oil suction screen
Note: Inspect only two of the components from each cylinder bank. Inspecting only two components will provide an adequate example of the condition of the other components.