TOHATSU BFT115A Service Manual page 444

CYLINDER HEAD
CYLINDER HEAD BOLT (11 × 155 mm)
Measure the bolt O.D. at the two points as shown.
STANDARD: 10.6 mm (0.417 in)
Replace the cylinder head bolt if its O.D. is smaller than
the service limit.
Measure the O.D. of all cylinder head bolts.
VALVE GUIDE REPLACEMENT
Chill the replacement valve guides in the freezer section
of a refrigerator for about an hour.
Use a hot plate or oven to heat the cylinder evenly to
150 °C (300 °F). Check the temperature with a
temperature indicating stick (available at a welding
supply store) or equivalent.
• Do not use a torch to heat the cylinder head;
warpage of the cylinder head may result.
• Do not get the head hotter than 150 °C (300 °F);
excessive heat may loosen the valve seats.
Remove the heated cylinder head from the hot plate,
and support it with wooden blocks. Wear heavy gloves
to protect your hands.
Drive the valve guide out of the combustion chamber
side using the special tool.
• Be careful not to damage the cylinder head mating
surface.
TOOL:
Valve guide driver,
5.35 × 9.7 (1)
Allow the cylinder head to cool to room temperature.
Clean and inspect the valve guide bores in the cylinder
head.
Use a hot plate or oven to heat the cylinder head evenly
to 150 °C (300 °F). Check the temperature with a
temperature indicating stick or equivalent.
14-52
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07742-0010100
50 mm 45 mm
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