10.1
Section 10
Inspection and Reconditioning
10
Section 10
Inspection and Reconditioning
This section covers the operation, inspection, and repair/reconditioning of major internal engine components. Also
included are water pump, cooling system and fan drive belt inspection criteria. The following components are not
covered in this section. They are covered in sections of their own:
Air Cleaner, Section 4
Carburetor & External Governor, Section 5
Ignition, Charging & Electric Starter, Section 8
Clean all parts thoroughly. Only clean parts can be accurately inspected and gauged for damage or wear. 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 or paint remover to remove the old RTV from the crankcase and closure plate.
Apply the solvent, give it time to work (5-10 minutes), and then brush the treated surface with a brass wire brush
to remove the softened RTV. Do not scrape the surfaces when cleaning as this will damage the surfaces and
could result in leaks.
Refer to ‘‘A Guide to Engine Rebuilding’’ (TP-2150) for additional information. ‘‘Measurement Guide’’ (TP-2159-A)
and ‘‘Engine Inspection Data Record’’ (TP-2435) are also available; use these to record inspection results.
LH630, LH685, LH750, LH760
Camshaft and Crankshaft
Inspection and Service
Inspect the gear teeth of the camshaft and crankshaft.
If the teeth are badly worn, chipped, or some are
missing, replacement will be necessary. If there is
tooth damage on either the camshaft gear or
crankshaft gear, both the camshaft and crankshaft
must be replaced.
Inspect the bearing surfaces for scoring, grooving, etc.
Measure the running clearance between the bearing
journals and their respective 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 bearing journals.
Subtract the journal diameters from their respective
bore diameters to get the running clearances. Check
the results against the specifications in Section 1. If
the running clearances are within specification, 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
closure plate will need to be replaced.
Inspect the crankshaft keyways. If worn or chipped,
replacement of the crankshaft will be necessary.
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