YANMAR

50 CHAPTER THREE
I
Intake port
Alternator drive belt replacement (all models)
1. Loosen the alternator retaining nuts (B, Figure 12).
2. Move the alternator inward sufficiently to allow removal
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.
To Intake
Def lecto~
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 removal
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.
0
Mesh
~rilled hole
hose
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 malfunctions,
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 intake
port or manifold. If the breather must be cleaned frequently,
determine the cause, such as broken or stuck
piston rings.
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 1 GMlO models, a reed valve system located
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-