Inspection - Briggs & Stratton Vanguard 10V300 Repair Manual

Inspection

1. Inspect governor gear as follows:
NOTE: Governor gear damage requires crankcase
replacement.
A. Inspect governor gear for worn, cracked, chipped,
or missing teeth.
B. Use your index finger to manually rotate the
governor gear in both directions. Verify that gear
rotates freely without roughness, sticking, or
unusual noise.
C. Spin governor gear to verify that flyweights move
freely.
2. Using an inside micrometer, check the crankcase and
the crankcase cover camshaft bearing bores for wear.
Replace either part if measurement is 0.554 inches
(14.068 mm) or more.
3. Check the crankcase for cracks or broken cooling
fins. Check the crankcase cover for cracks. Replace
parts as necessary.
4. Check for scratches and nicks on all gasket sealing
surfaces. Use a fine-tooth file to carefully remove any
nicks or burrs found.
5. Check the crankcase and crankcase cover for
stripped threads.
NOTE: Stripped threads can sometimes be repaired
using a helicoil, but replace parts if thread damage is
severe or present at multiple locations.
6. Inspect the cylinder bore for defects or damage in the
ring travel area. Replace crankcase if the cylinder is
severely scored, scuffed, scratched, burnt, or gouged.
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7. Using Magnaflux Dye Penetrant, inspect the cylinder
bore for cracks. If no cracks are found, thoroughly
wash cylinder to remove traces of dye.
8. Check the cylinder to cylinder head mating surface for
warpage or distortion. Discard the crankcase if any
low spot is 0.002 inches (0.05 mm) or more. Proceed
as follows:
A. See A of Figure 77. Set a straightedge diagonally
across the length of the cylinder intersecting the
upper and lower corners of the gasket surface.
B. Slide a feeler gauge beneath the straightedge to
check for warpage.
C. Check the opposite diagonal to verify that the
gasket surface is flat.
D. See B of Figure 77. Set a straightedge vertically
across the length of the cylinder gasket surface.
Use feeler gauge to check for warpage. Repeat
step on opposite side.
E. See C of Figure 77. Set a straightedge
horizontally across the length of the cylinder
gasket surface. Use feeler gauge to check for
warpage. Repeat step on opposite side.
9. Repeat the 6 point check outlined under step 8 to
check for warpage or distortion of the crankcase to
crankcase cover mating surfaces. Be sure to check
both crankcase and crankcase cover. Discard the
crankcase or crankcase cover if any low spot is 0.002
inches (0.05 mm) or more.
10. Obtain the Dial Bore Gauge (Part No. 19487) to
check the cylinder bore for out-of-round and taper.
Proceed as follows:
NOTE: If the Dial Bore Gauge is not available, use
the Telescoping Gauge (Part No. 19485) and Dial
Caliper (Part No. 19609).
A. See Figure 78. At the top of the piston ring travel
zone, measure the cylinder bore diameter at
two locations- parallel and perpendicular to the
crankshaft (A-B). Write the readings down.
B. Repeat the two measurements at the center of
the piston ring travel zone (C-D).
C. Repeat the two measurements again at a point
below the piston ring travel zone (E-F).
D. If the two measurements at the top, middle or
bottom of the bore vary by more than 0.0015
inches (0.04 mm), then the cylinder is out-of-
round.
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