Valve Guide Replacement - TOHATSU BFT250A Service Manual

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CYLINDER HEAD
CYLINDER HEAD BOLT/WASHER
Measure the bolt O.D. at the two points as shown.
STANDARD: 11.3 mm (0.44 in)
Replace the cylinder head bolt/washer if its O.D. is
smaller than the service limit.
Measure the O.D. of all cylinder head bolt/washers.

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 (302°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 (302°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 a valve guide driver (special tool).
TOOL:
Valve guide driver, 5.35 x 9.7 mm [1] 07742-0010100
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 (302°F). Check the temperature with a
temperature indicating stick or equivalent.
14-42
75 mm (3.0 in)
[1]
40 mm
(1.6 in)