GASOLINE ENGINE 8.1 S INBOARD MODELS
Page 12 of 58
Exhaust System
CAUTION
It is the responsibility of the boat manufacturer or installing dealer to properly lo-
cate the engine and install the exhaust system. Improper installation may allow wa-
ter to enter the exhaust manifolds and combustion chambers and severely damage
the engine. Damage caused by water in the engine will not be covered by Mercury
MerCruiser Warranty, unless this damage is the result of defective parts.
Determine if exhaust elbow risers are required, by taking measurements “
a
” and “
b
,” with
boat at rest in the water and maximum load aboard. Subtract “
b
” from “
a
” to find “
c
.” If “
c
”
is less than specified in chart, select appropriate size exhaust elbow riser kit, and exhaust
extension kit if applicable, that will correctly position exhaust elbow.
Model
“
c
” = “
a
” Minus “
b
”
8.1S HO
8.1 Horizon
“
c
” Must Be 15 in. (381 mm) or More
77642
d
b
c
a
When designing and installing exhaust system, it is very important that the following points
be taken into consideration:
•
System layout and construction must prevent cooling system discharge water from flow-
ing back into engine and also must prevent seawater from entering engine via exhaust
system.
•
The exhaust hoses and pipes must not be higher than exhaust elbows at any point.
•
The drop must be constant so that a low spot does not exist at any point in the exhaust
hose or pipe.
