MTD 61 series, Shop Manual

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61, 65 and 70 Series Vertical Shaft Engines
68
Lubrication system
MTD uses a splash lube system for it’s vertical shaft
engines. The governor gear has paddles on it that
“splashes” oil around the inside of the engine. See Figure
5.6.
The splashing action will also atomize or change the
oil into a mist. There are two oil passages that run along
the engine cylinder. The one on the top side of the engine
is the oil supply passage. The oil mist will flow through this
passage to the cylinder head. The supply passage lines up
with the top crank arm so that some of the oil on the crank
arm will be flung into the supply passage, forcing addi-
tional oil up to the cylinder head. See Figure 5.7.
The second oil passage runs along the bottom side of
the cylinder. This is the oil return passage. As the name
implies, it allows the oil collecting in the cylinder head to
return to the sump. The return passage can be identified
by the plastic drain tube that is attached to it, inside of the
engine. See Figure 5.8.
NOTE: Not all engine have this drain tube.
NOTE: Because these engines use splash lubrica-
tion, the type of oil and the oil level is critical
for proper operation of the engine. If the oil
level is too low, the paddles on the governor
gear can not splash the oil into the engine. If
the oil level is too high, the oil will not change
into a mist to reach the upper side of the
engine.
Figure 5.6
Governor
gear
Paddles
Figure 5.7
Figure 5.8
Drain tube