Perkins 5006A-E23TA Operation And Maintenance Manual page 90

90
Maintenance Section
Overhaul (Top End)
Other 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 vibration
An 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: 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 Perkins Engines Stafford
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
During a major overhaul, all the bearings, seals,
joints, and components that wear should be
disassembled. The parts should be cleaned. The
parts should then be inspected. If necessary, the
parts should be replaced. The crankshaft should be
inspected and measured for wear. The crankshaft
may require regrinding. Alternatively, the crankshaft
may be replaced.
Inspecting Components
Inspect the following components during a major
overhaul.
• Radiator and system
• Camshaft
• Camshaft followers
• Connecting rods and bearings
• Crankshaft and bearings
• Gear train
• Inlet air piping
• Oil cooler
• Pistons and rings
• Cylinder liners
• Cylinder heads
• Inlet and exhaust valves
Replace the crankshaft vibration dampers.
Overhaul (Top End)
Scheduling a Top End Overhaul
Top end overhauls should be scheduled according to
the recession of the 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.
Note: Generally, cylinder heads wear out at different
rates. Sometimes, servicing the cylinder heads at
different times may be the most economic decision.
This action 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 to determine if cylinder heads should be
serviced as a group or divided into smaller groups.
Top End Overhaul Information
A top end overhaul involves servicing the cylinder
heads. During a top end overhaul, one piston should
be removed. Inspect the piston, piston rings, and the
cylinder liner. The condition of these components will
determine the period of the major overhaul. Refer to
Service Manual for more information.
Monitoring Valve Seat Wear
Record the engine valve lash, for more information
refer to the Operation and Maintenance Manual,
"Maintenance Interval Schedule". The monitoring of
the valve seat wear should be carried out before any
adjustment of the valve lash.
1. Remove the rocker covers.
2. Refer to Systems Operation, Testing and
Adjusting, "Valve Lash - Adjust".
3. On all engine cylinders, record the clearance
before any adjustments are made.
4. Set the valve bridges.
5. Adjust the valve lash to 0.4 mm (0.016 inch).
The recorded values can be used to identify any
excessive valve seat wear on individual valves. The
recorded values can be used to schedule a top end
overhaul.
An example of recorded valve lash
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