9.1
Section 9
Inspection and Reconditioning
9
Section 9
Inspection and Reconditioning
This section covers the operation, inspection, and
repair/reconditioning of major internal engine
components. The following components are not
covered in this section. They are covered in sections of
their own:
Air Cleaner, Section 4
Fuel Injection & External Governor, Section 5
Ignition, Charging & Electric Starter, Section 7
Clean all parts thoroughly. Only clean parts can be
accurately inspected and gauged for wear or damage.
There are many commercially available cleaners
that will quickly remove grease, oil, and grime from
engine parts. When such a cleaner is used, follow the
manufacturer’s instructions and safety precautions
carefully. Make sure all traces of the cleaner are
removed before the engine is reassembled and placed
into operation. Even small amounts of these cleaners
can quickly break down the lubricating properties of
engine oil.
Use an aerosol gasket remover, paint stripper, or
lacquer thinner to remove any old sealant. Apply the
solvent, allow time for it to work, and then brush the
surface with a brass wire brush. A er the old sealant
is removed, clean the surface with isopropyl alcohol,
lacquer thinner, or aerosol electrical contact cleaner.
Do not scrape the surfaces, as any scratches, nicks, or
burrs can result in leaks. See Service Bulletin 252 for
further information.
Refer to A Guide to Engine Rebuilding (TP-2150-A) for
additional information. Measurement Guide
(TP-2159-B) and Engine Inspection Data Record
(TP-2435) are also available; use these to record
inspection results.
Camshaft
Inspection and Service
Check the lobes of the camsha for wear or damage.
See Section 1 for minimum li specifi cations. The
measurement must be performed while the valve
train is still assembled. Inspect the cam gear for badly
worn, chipped or missing teeth. Replacement of the
camsha will be necessary if any of these conditions
exist.
Crankshaft
Inspection and Service
Inspect the gear teeth of the cranksha . If the teeth
are badly worn, chipped, or some are missing,
replacement of the cranksha will be necessary.
Inspect the cranksha bearing surfaces for scoring,
grooving, etc. Measure the running clearance between
the cranksha journals and their respective bearing
bores. Use an inside micrometer or telescoping gauge
to measure the inside diameter of both bearing bores
in the vertical and horizontal planes. Use an outside
micrometer to measure the outside diameter of the
cranksha main bearing journals. Subtract the journal
diameters from their respective bore diameters to get
the running clearances. Check the results against the
specifi cations in Section 1. If the running clearances
are within specifi cation, and there is no evidence
of scoring, grooving, etc., no further reconditioning
is necessary. If the bearing surfaces are worn or
damaged, the crankcase and/or oil pan will need to be
replaced.
Inspect the cranksha keyways. If worn or chipped,
replacement of the cranksha will be necessary.
Inspect the crankpin for score marks or metallic
pickup. Slight score marks can be cleaned with
crocus cloth soaked in oil. If wear limits, as stated in
Specifi cations and Tolerances are exceeded, it will be
necessary to either replace the cranksha or regrind
the crankpin to 0.25 mm (0.010 in.) undersize. If
reground, a 0.25 mm (0.010 in.) undersize connecting
rod (big end) must then be used to achieve proper
running clearance. Measure the crankpin for size,
taper, and out-of-round.
NOTE: If the crankpin is reground, visually check to
ensure that the fi llet blends smoothly with
the crankpin surface. See Figure 9-1.
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