50
B
Alternator drive belt replacement (all models)
1. Loosen the alternator retaining nuts (B,
Figure
12).
2. Move the alternator inward sufficiently to allow re-
moval
of
the belt from the pulleys and remove the belt.
3. Clean the pulley grooves so they are dry and free
of
rust or other corrosion.
4. Place the new belt in the pulley grooves.
5. Adjust belt tension as previously described.
Seawater
pump
drive belt replacement (2GM, 2GM20,
3GM, 3GM30,
3HM
and
3HM35
models)
1. Remove the alternator drive belt as described in the
previous section.
2. Loosen the screws that secure the seawater pump
mounting plate (B,
Figure
14).
3. Move the alternator inward sufficiently to allow re-
moval
of
the belt from the pulleys and remove the belt.
4. Clean the pulley grooves so they are dry and free
of
rust or other corrosion.
5. Place the new belt in the pulley grooves.
6. Adjust belt tension as previously described.
Crankcase
Breather
The crankcase breather assembly vents crankcase
pressure into the intake port or manifold. This produces a
negative pressure in the crankcase.
If
the breather mal-
functions, oil may be forced past the piston rings, oil seals
and gaskets.
Periodic maintenance is not normally required unless
excessive oil gasses clog the crankcase breather. This is
usually indicated by blue exhaust smoke or oil in the in-
take port or manifold.
If
the breather must be cleaned fre-
quently, determine the cause, such as broken or stuck
piston rings.
CHAPTER
THREE
Reed
valve
Intake
port
-t~---tIt-----IIt-
Deflector
Drilled hole
Mesh--_II!I'li:'~
Refer to Chapter Five or Six for service procedures for
the crankcase breather. Refer to the following paragraphs
for a description
of
the breather on specific models.
On IGM and IGMIO models, a reed valve system lo-
cated on the rocker arm cover controls crankcase gas
movement. See
Figure
15. The reed valve opens when the
downward moving piston increases crankcase gas pres-
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