The need for a major overhaul is determined by several factors.
- An increase of oil consumption
- An increase of crankcase blowby
- A decrease and variation of cylinder compression
Other factors must also be considered for determining a major overhaul:
- The total amount of fuel consumption
- The wear metal analysis of the lube oil
- An increase in the levels of noise and vibration
An increase of wear metals in the lube oil indicates that the bearings and the surfaces that wear will need serviced. An increase in the levels of noise and vibration indicates that rotating parts require service.
Note: Oil analysis can indicate a decrease of wear metals in the lube oil. The cylinder liners may be worn so that polishing of the bore occurs. Also, the increased use of lube oil will dilute the wear metals.
Monitor the engine as the engine accumulates service hours. Consult your Cat dealer about scheduling a major overhaul.
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.
A major overhaul includes all of the work that is done for top end overhauls. A major overhaul includes additional parts and labor. Additional parts and labor are required in order to rebuild the engine.
For the major overhaul, all of the bearings, seals, gaskets, and components that wear are disassembled. The parts are cleaned and inspected. If necessary, the parts are replaced. The crankshaft is measured for wear. The crankshaft may require regrinding. Alternatively, the crankshaft may be replaced with a Cat replacement part.
Your Cat dealer can provide these services and components. Your Cat dealer can ensure that the components are operating within the appropriate specifications.
If you elect to perform an overhaul without the services of a Cat dealer, be aware of the following recommendations.
Fuel Consumption Before A Major Overhaul
The overhaul interval that is listed in this Operation and Maintenance Manual, "Maintenance Interval Schedule" is expressed in service hours. A more accurate figure to use is fuel consumption. Fuel consumption corresponds more accurately to the engine load. Table 1 lists an average range of fuel consumption for a reasonable load factor before a major overhaul.
| Approximate Fuel Consumption Before A Major Overhaul | |
| Engine Model | Fuel Consumption |
| C280-16 | |
Remanufacturing or Rebuilding of Components
Rework the following components.
- Air shutoff valve
- Centrifugal oil filter bearings
- Cylinder heads
- Starting motor
Replace the following components.
- Accessory group bearings
- Connecting rod bearings
- Cylinder head gaskets
- Cylinder head valves and valve guides
- Cylinder head valve spring guides
- Exhaust manifold gaskets
- Exhaust manifold seals and bellows
- Exhaust shields
- Front gear train bearings
- Inlet air line seals
- Oil temperature regulators and seals
- Unit injectors
- Water pump bearings and seals
- Water temperature regulators and seals
Inspection and/or Replacement of Components
Inspect the following components according to the instructions that are in AVSpare reusability publications. Refer to Guidelines for Reusable Parts and Salvage Operations, SEBF8029, "Index of Publications on Reusability or Salvage of Used Parts". Replace the components, if necessary.
- Aftercooler core
- Alarm and shutoff controls
- Camshafts
- Camshaft bearings
- Connecting rod bearings
- Crankshaft
- Cylinder liners
- Cylinder sleeves
- DEF pump
- Exhaust manifolds
- Front gear group
- Fuel transfer pump seals
- Main bearings
- Oil cooler seals
- Oil pump bushings and seals
- O-Ring seals and plugs
- Pistons and piston rings
- Priority valve
- Rear gear group
- Rear gear train bearings and seals
- Rocker arm bearings
- Thermocouples
- Thrust bearings
- Turbocharger bearings, bushings, and seals
- Valve lubricator pump, gaskets, and seals
- Valve mechanism group
- Water pump bearing and seals
Inspect the camshaft for damage to the journals and the lobes. Inspect the following components for signs of wear and/or for signs of scuffing:
- camshaft bearings
- camshaft followers
Inspect the crankshaft for any of the following conditions:
- deflection
- damage to the journals
- bearing material that has seized to the journals
Check the journal taper and the profile of the crankshaft journals. Check these components by interpreting the wear patterns on the following components:
- rod bearing
- main bearings
Note: If the crankshaft or the camshaft are removed for any reason, use the magnetic particle inspection process to check for cracks.
Replace the crankshaft vibration damper if any of the following conditions occur:
- Engine failure due to a broken crankshaft
- Excessive wear of the front bearing for the crankshaft
- Excessive wear of the gear train that is not caused by a lack of lubrication
Inspect the gears of the gear train and inspect the gear train bushings for the following conditions:
- Worn gear teeth
- Unusual fit
- Unusual wear
Cleaning and Inspection of Components
Clean the following components. Inspect the components for good condition. Replace the components, if necessary.
Replace the gaskets and seals for the components.
- Air inlet lines
- Camshaft front covers
- Camshaft drive gear covers
- Central structure covers
- Crankcase side covers
- Crankshaft
- Crankshaft vibration damper
- Front housing group
- Fuel lines
- Fuel transfer pump
- Gear inspection group
- Oil cooler core
- Oil lines
- Oil suction screen
- Power take-off covers
- Priority valve group
- Rear housing group
- Rear structure covers
- Valve covers
- Water lines