BOLT 9S1374 - Caterpillar

Scheduling a Major Overhaul
Generally, a major overhaul is performed at the fifth top end overhaul. The need for a major overhaul is determined by several factors. Some of those factors are the same factors that determine the in-frame overhaul:
An increase of oil consumption
An increase of crankcase blowby
A decrease and variation of cylinder compressionOther factors must also be considered for determining a major overhaul:
The service hours of the engine
The wear metal analysis of the lube oil
An increase in the levels of noise and vibrationAn increase of wear metals in the lube oil indicates that the bearings and the surfaces that wear may need to be serviced. An increase in the levels of noise and vibration indicates that rotating parts require service.Note: It is possible for oil analysis to 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 Caterpillar 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.Major Overhaul Information
A major overhaul includes all of the work that is done for top end overhauls and in-frame overhauls. A major overhaul includes additional parts and labor. Additional parts and labor are required in order to completely rebuild the engine. In some cases, the engine is relocated for disassembly.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 Caterpillar replacement part.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 the major overhaul.
Camshaft bearings
Connecting rod bearings
Coupling (tandem engines)
Cylinder liners
Piston rings
Cylinder heads, gaskets, and bolts
Gaskets and seals
Gear train bearings
Main bearings
Oil temperature regulators
Water temperature regulators
Wiring harnessesRebuilding or Replacing of Components
Rebuild the following components during the major overhaul.
Carburetor
Crankshaft vibration damper 1.
Exhaust bypass
Gas regulator
Prelube pump
Starting motor
Turbochargers
Water pumpsNote: 1. Replace the crankshaft vibration damper if the damper cannot be rebuilt.Inspecting 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".
Aftercooler
Camshafts
Camshaft followers
Connecting rods
Crankshaft
Gear train
Governor
Inlet air piping
Oil cooler
Oil pump
Pistons
Transformers